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Dettagli della rivista
Formato
Rivista
eISSN
1899-7562
Pubblicato per la prima volta
13 Jan 2009
Periodo di pubblicazione
5 volte all'anno
Lingue
Inglese

Cerca

Volume 73 (2020): Edizione 1 (July 2020)

Dettagli della rivista
Formato
Rivista
eISSN
1899-7562
Pubblicato per la prima volta
13 Jan 2009
Periodo di pubblicazione
5 volte all'anno
Lingue
Inglese

Cerca

28 Articoli

Section I – Kinesiology

Accesso libero

Push-Ups are Able to Predict the Bench Press 1-RM and Constitute an Alternative for Measuring Maximum Upper Body Strength Based on Load-Velocity Relationships

Pubblicato online: 21 Jul 2020
Pagine: 7 - 18

Astratto

Abstract

The aims of this study were firstly to compare the similarity in upper-body muscle activation between the bench press and push-up at similar loads, and secondly to establish a 1-RM prediction equation between the two exercises based upon the load-velocity relationship. Twenty resistance-trained male athletes (age 22.5 ± 5.24 years, body mass 83.7 ± 10.7 kg, body height 1.80 ± 0.06 m) performed push-ups and bench presses with four different loads. Push-ups were performed without a weight vest and with a 10-20-30 kg weight vest. Bench presses were performed at 50-80% of athletes’ assumed 1 repetition max (1-RM) in 10 kg steps, while a linear encoder measured performance during the exercises. A load-velocity relationship was established as a product of the load and velocity for the push-up and bench press per participant and the equation was used to establish a predicted 1-RM. Mean muscle activation of eight upper body muscles was recorded for each exercise and each load. The main findings of this study demonstrate an extremely large association between the predicted 1-RM loads performed with the push-up and bench press (r = 0.93) in experienced resistance trained men. Furthermore, most muscles showed similar activations between the two exercises with the different loads except the deltoid and biceps brachii muscles. It may be concluded that it is possible to predict a cross-over 1-RM between the two exercises based upon the load-velocity relationship in each exercise, and that training push-ups largely targets the same muscles as the bench press except the deltoid and biceps muscles. For coaches and athletes, the use of this method is a low cost and time-effective alternative for standard 1-RM bench press testing to predict maximal upper body strength.

Key words

  • mean velocity
  • resistance training
  • strength
  • upper-body
Accesso libero

The Applications of Landing Strategies in Badminton Footwork Training on a Backhand Side Lateral Jump Smash

Pubblicato online: 21 Jul 2020
Pagine: 19 - 31

Astratto

Abstract

Previous research in badminton has associated unilateral landings following overhead strokes with the occurrence of knee injuries. Smashing involves tensing the abdomen muscles while swinging the racket rapidly and maintaining one’s balance while performing coordinated movements and steps; this process puts stress on the player’s lower limbs. However, few studies have compared the effects of different stroke training while performing various types of badminton strokes. This study investigated the influence of different stroke training on the smash action of badminton players. Three stroke training conditions were considered: shadow, target striking, and smashing. Sixteen male experienced badminton players were recruited for this study. One-way repeated-measures ANOVA with Bonferroni correction was used to identify the differences. At the initial contact with the ground, the knee flexion and knee valgus angles under the smash condition were significantly higher than target and shadow conditions. Under the smash condition, hip abduction was significantly higher than under the target and shadow conditions. Moreover, the hip abduction under the target condition was significantly higher than under the shadow condition. At the maximum knee flexion, the hip abduction under the smash and target conditions was significantly higher than under the shadow condition. Regarding the time from the moment of initial contact to the peak of vertical ground reaction force it was shorter under the smash condition than the target and shadow conditions. The vertical ground reaction force was higher under the smash condition than under the target and shadow conditions. The 50 ms impulse was higher under the smash condition than under the target and shadow conditions. The main findings of this study are that under the smash condition, the motion in the frontal plane increased, which produced higher loads on the joints in the lower limbs. Player performed the same footwork under the three conditions, but the landing strategies differed because of unique swing motions and techniques. The condition under which a player hits a shot to a target area can affect the landing. The results of this study suggest that target practice is more effective for improving the landing technique employed during actual shots than shadow practice.

Key words

  • motion analysis
  • footwork training
  • lateral jump smash
Accesso libero

The Effects of Altering the Concentric/Eccentric Phase Times on EMG Response, Lactate Accumulation and Work Completed when Training to Failure

Pubblicato online: 21 Jul 2020
Pagine: 33 - 44

Astratto

Abstract

This study compared the electromyographic response, the blood lactate concentration (BLC), and the maximum number of repetitions (MNR) between protocols of different concentric/eccentric duration taken to muscle failure. This comparison may help to understand how different concentric/eccentric duration may influence performance and the central and metabolic responses in trained men. Seventeen strength-trained men performed two protocols in a counterbalanced design. Three sets of the Smith bench press exercise were performed to failure at 60% of the one-repetition maximum (1RM) using each protocol (4-s concentric/2-s eccentric [4 s: 2 s]; and 2-s concentric/4-s eccentric [2 s: 4 s]). The normalized root mean square (EMGRMS) and the mean frequency (EMGMF) of the electromyographic signals for the pectoralis major and the triceps brachii were compared in the first, middle, and last repetitions. The BLC was assessed at rest, during and after the test sessions. To compare the EMG and BLC, a 3-way ANOVA with repeated measures with a post hoc Tukey’s test was used. To compare the MNR performed across the sets, an ANOVA-type rank test with the Dunn’s post hoc test was used. The ANOVA indicated a greater EMGRMS for Protocol 4 s: 2 s in the pectoralis major and a lower EMGMF for Protocol 4 s: 2 s in the triceps brachii at the middle and last repetitions. Both protocols increased the EMGRMS and decreased the EMGMF across repetitions. Despite the results show different levels of activation and neuromuscular fatigue between protocols, the BLC and the MNR were similar.

Key words

  • physiology
  • strength
  • electromyography
  • bench press
  • central fatigue
Accesso libero

The Reactive Bounding Coefficient as a Measure of Horizontal Reactive Strength to Evaluate Stretch-Shortening Cycle Performance in Sprinters

Pubblicato online: 21 Jul 2020
Pagine: 45 - 55

Astratto

Abstract

Plyometric exercises such as drop jumping and bounding offer athletes a substantiated means of enhancing athletic performance. Between the two exercises, reactive measurement using bounding (reactive bounding coefficient [RBC]) has received scant attention within the domain of training and conditioning. Therefore, this study aimed to identify the viability of utilising a speed-bounding exercise to assess horizontal reactive strength. Eleven young, male elite sprinters (age: 17.8 ± 1.3 yr; body height: 1.72 ± 0.06 m; body mass: 66.05 ± 6.10 kg; best 100 m sprint time: 10.77 ± 0.32 s) were tested for static jumps (SJ), drop jumps (DJ), 10 speed-bounding (RBC10), and 50 m sprint performance. Between-group comparisons based on sprint ability (fast [FSG] vs. slow [SSG] sprint-group) and correlation coefficients were computed subsequently. The FSG (n = 5; 50 m time: 5.82 ± 0.11 s; RBC10: 7.46 ± 0.27) performed significantly better in the RBC10 (p = 0.036) than the SSG (n = 5; 50 m time: 6.09 ± 0.13 s; RBC10: 7.09 ± 0.25). A very high correlation was attained between the RBC10 and the criterion measure, the SJ (r = 0.83). Additionally, RBC10 appeared to be correlated with 30, 50, 10-30 and 30-50 m sprint times (r = -0.52 to -0.60). This positive trend, however, was not observed for the DJ reactive strength index (trivial to moderate correlations). Good reliability was shown for the RBC10 and all sprint distances (“1.5% coefficient variation). Furthermore, all sprinters attained ground contact times of 0.12-0.18 s during the RBC10 which was indicative of fast stretch-shortening cycles during movement, suggesting that the RBC10 could be utilised to assess plyometric ability and enhance sprint performance. Overall, the RBC10 seems able to discriminate between the FSG and the SSG, indicating it has acceptable levels of validity and reliability.

Key words

  • athletics
  • explosive
  • plyometric
  • power
  • speed-strength
  • sprinting
Accesso libero

Kinematic Mobile Drop Jump Analysis at Different Heights Based on a Smartphone Inertial Sensor

Pubblicato online: 21 Jul 2020
Pagine: 57 - 65

Astratto

Abstract

The purpose of this study was to describe the acceleration variables in a plyometric jump test using the inertial sensor built into an iPhone 4S® smartphone, and the jumping variables from a contact mat. A cross-sectional study was conducted involving 16 healthy young adults. Linear acceleration, flight time, contact time and jump height were measured in a drop jump test from 60 cm and from 30 cm. Greater acceleration values were found in the drop jump test from 60 cm; the same was observed for the values from the contact mat. Multiple regression analysis was performed for each drop jump test: jump height was used as the dependent variable, and the most relevant variables were used as predictor variables (weight and maximum angular velocity in the Y axis for analysis of the drop jump from 60 cm, and weight and maximum acceleration in the Z axis for the drop jump from 30 cm). We found a significant regression model for the drop jump test from 60 cm (R2 = 0.515, p “ 0.001) and for the test from 30 cm (R2 = 0.460, p “ 0.01). According to the results obtained in this study, the built-in iPhone 4S® inertial sensor is able to measure acceleration for healthy young adults performing a vertical drop jump test. The acceleration kinematic variables are higher in the drop jump test from 60 cm than from 30 cm.

Key words

  • acceleration
  • biomechanics
  • physical performance
  • plyometric training
Accesso libero

A Finite Element Model for Estimation of Contact Dynamics During a Jumping Movement on a Trampoline

Pubblicato online: 21 Jul 2020
Pagine: 59 - 72

Astratto

Abstract

In order to fully understand contact dynamics on a trampoline, a simulation approach using a musculoskeletal model coupled with a dynamic model of the trampoline is essential. The purpose of the study was to examine dynamics and selected lower extremity muscle forces in a landing and jumping movement on a trampoline, using a combination of finite element modeling and musculoskeletal modeling. The rigid frame of the trampoline was modeled in ADAMS and coupled with a finite element model of the elastic trampoline net surface in ANSYS. A musculoskeletal model of an elite trampoline athlete was further developed in LifeMod and combined with the finite element model of the trampoline. The results showed that the peak trampoline reaction forces (TRF) were 3400 N (6.6 BW) and 2900 N (5.6 BW) for the left and right limb, respectively. The right hip, knee and ankle joint reaction forces reached the maximum between 3000-4000 N (5.8 – 7.7 BW). The gluteus maximum and quadriceps reached the maximum muscle force of 380 N (0.7 BW) and 780 N (1.5 BW), respectively. Asymmetric loading patterns between left and right TRFs and lower extremities joint reaction forces were observed due to the need to generate the rotational movement during the takeoff. The observed rigid and erect body posture suggested that the hip and knee extensors played important roles in minimizing energy absorption and maximizing energy generation during the trampoline takeoff.

Key words

  • trampoline
  • finite element model
  • musculoskeletal model
  • landing technique

Section II – Exercise Physiology & Sports Medicine

Accesso libero

Circulating Inflammatory Biomarkers and Endocrine Responses to Exercise in Female Soccer Players

Pubblicato online: 21 Jul 2020
Pagine: 73 - 82

Astratto

Abstract

The objective of the study to determine the effects of graded exercise on the cytokines and insulin-like growth factor-1 (IGF-1), growth hormone (hGH), testosterone (T), and cortisol (C) concentrations in the peripheral blood of female soccer players, and to evaluate if increased inflammatory biomarkers were related to these hormones and performance variables. Sixteen female soccer players (N = 16, age 19.3 ± 2.3 years) participated in this study. Blood samples were collected at three time points: pre-exercise, post-exercise, and in the 15th minute of recovery, to evaluate morphological and biochemical variables. The relative expression of IL-6 (interleukin 6) and serum concentrations of the cytokines were increased in the recovery period compared to pre-exercise levels (p = 0.03 and p=0.005, respectively). There was a significant effect of exercise on serum hGH level (p “ 0.001), T/C ratio (p = 0.001), and C level (p=0.02). Positive correlations were found between: post-exercise IL-1β (interleukin 1 beta) and IL-6 (R = 0.84, p = 0.000), and the IL-6 and TNF-α (tumor necrosis factor alpha) gene expression during recovery (R = 0.65, p = 0.009), and serum IL-1β post-exercise and maximal power (R = 0.68; p = 0.004). Exercise-induced serum C levels positively correlated with IGF-1 levels (R = 0.52 p = 0.05). Negative associations were revealed between post-exercise T/C ratio and IGF-1 (R = - 0.58, p = 0.03) and serum free T and IL- β (R = -0.56, p = 0.04) levels. The low level of pre-exercise genes and protein of the IL-1β, IL-6 and TNF-α indicate a lack of inflammation signs in the female soccer players. This study shows significant effects of exercise on hormone levels and pro-inflammatory markers, which could be used to identify the role of female sex steroids on the immune function.

Key words

  • cytokine
  • hormones
  • female soccer players
  • exercise performance
Accesso libero

Analysis of Morphofunctional Variables Associated with Performance in Crossfit® Competitors

Pubblicato online: 21 Jul 2020
Pagine: 83 - 91

Astratto

Abstract

CrossFit® is a competitive sport and fitness modality characterized by multiple physical capabilities and multi-joint movements. This study aimed to analyse and classify variables related to CrossFit® competitors’ specific performance. Fifteen male CrossFit® competitors were selected (n = 15; 30.57 ± 5.5 years; 1.76 ± 0.06 m; 78.55 ± 9.12 kg). Mean values were obtained for body mass index (25.3 ± 2.14 kg/m2), 4 skinfolds, 1 repetition maximum in the squat (137.60 ± 19.65 kg) and the bench press (101.67 ± 10.64 kg), maximum pull-ups (18.87 ± 5.05), sit-ups in 60 s (46.60 ± 4.22), peak power in the countermovement jump (3908.04 ± 423.68 W), VO2max with a shuttle run test (47.70 ± 4.79 ml kg-1·min-1), and time in the Workout of the Day (WOD) “Fran” (337.13 ± 119.19 s) and “Donkey Kong” (417.47 ± 98.44 s) components. Principal component analysis was conducted to classify variables and to select those most related to each new component (“strength and muscle mass”, “adiposity” and “aerobic capacity”). The correlation matrix was analysed, indicating significant correlations between “Donkey Kong” and VO2max (r = -.675; p “ .01), suprailiac skinfold (r = .713; p “ .01) and sit-ups (r = -.563; p “ .05); and between “Fran” and squat (r = -.528; p “ .05). Three important components characterizing CrossFit® competitors were identified: “strength and muscle mass”, low “adiposity” and “aerobic capacity”. Significant relationships between morphofunctional variables and Crossfit® performance were found in Crossfit® competitors.

Key words

  • high intensity interval training
  • power
  • principal component analysis
  • Crossfit
  • performance
Accesso libero

Reliability and Validity of Maximal Mean and Critical Speed and Metabolic Power in Australian Youth Soccer Players

Pubblicato online: 21 Jul 2020
Pagine: 93 - 102

Astratto

Abstract

The reliability and validity of maximal mean speed (MMS), maximal mean metabolic power (MMPmet), critical speed (CS) and critical metabolic power (CPmet) were examined throughout the 2016-2017 soccer National Youth League competitions. Global positioning system (GPS) data were collected from 20 sub-elite soccer players during a battery of maximal running tests and four home matches. A symmetric moving average algorithm was applied to the instantaneous velocity data using specific time windows (1, 5, 10, 60, 300 and 600 s) and peak values were identified. Additionally, CS and CP¬met values calculated from match data were compared to CS and CPmet values determined from previously validated field tests to assess the validity of match values. Intra-class correlation (one-way random absolute agreement) scores ranged from 0.577 to 0.902 for speed, and from 0.701 to 0.863 for metabolic power values. Coefficients of variation (CV) ranged from good to moderate for speed (4-6%) and metabolic power (4-8%). Only CS and CPmet values were significantly correlated (r = 0.842; 0.700) and not statistically different (p = 0.066; 0.271) to values obtained in a shuttle-running critical test. While the present findings identified match-derived MMS, MMPmet, CS and CPmet to be reliable, only CS and CPmet derived from match play were validated to a CS field test that required changes in speed and direction rather than continuous running. This suggests that both maximal mean and critical speed and metabolic power analyses could be alternatives to absolute distance and speed in the assessment of match running performance during competitive matches.

Key words

  • soccer
  • global positioning system
  • external load
Accesso libero

Can Heart Rate Variability Biofeedback Improve Athletic Performance? A Systematic Review

Pubblicato online: 21 Jul 2020
Pagine: 103 - 114

Astratto

Abstract

This systematic review was conducted to evaluate the effect of heart rate variability biofeedback (HRV BFB) on performance of athletes. Six electronic databases (Springerlink, SportDiscus, Web of Science, PROQUEST Academic Research Library, Google Scholar, and ScienceDirect) and article references were searched. Eligibility criteria were: 1. experimental studies involving athletes randomly allocated among groups (randomized control trial); 2. availability of HRV BFB as a treatment compared to a control condition (CON) that involves regular sport/dance training, a placebo (PLA) or other methods of BFB; 3. performance-related variables such as a dependent index; and, 4. peer-reviewed articles written in English. Out of 660 articles, six studies were included in the systematic review which involved 187 athletes (females: n = 89; males n = 98). Six studies compared HRV BFB with a CON, three studies compared HRV BFB with a PLA, and two studies differentiated HRV BFB with other methods of BFB. Findings support HRV BFB as a potential intervention to improve fine and gross motor function in athletes.

Key words

  • heart rate variability
  • biofeedback
  • athletes
  • performance
  • resonant frequency breathing
Accesso libero

Cardiac Parasympathetic Reactivation Following Small‐Sided Games, Repeated Sprints and Circuit Training in Elite Handball Players

Pubblicato online: 21 Jul 2020
Pagine: 115 - 124

Astratto

Abstract

To compare acute parasympathetic reactivation following usual training exercises, the acute post-exercise heart rate (HR) and heart rate variability (HRV) were analysed. Fourteen elite male handball players completed three separate sessions of 16-min small-sided games (SSGs), repeated sprints (RSs) consisting of two sets of six repetitions of a 25-m sprint with a 180° change of direction (12.5 m + 12.5 m) every 25 s and 40 min of handball-specific circuit training (CT, one brief action every 40 s). The HR was recorded during the exercises; HRV was assessed 10 min before and after exercise. The exercise HR was higher for SSGs than RSs and it was higher for RSs than CT. Comparison of the baseline and acute post-exercise HRV values showed that parasympathetic indices decreased following SSG (p < 0.01 – p < 0.0001; large effect size) and RS (p < 0.05 –p < 0.01; large effect size) interventions. For CT, recovery values remained similar to the baseline (small effect size). The comparison of the acute recovery period between exercise modalities showed that the root mean square of the successive differences (RMSSD) was lower for SSGs than RSs and CT. No difference in any HRV indices was observed between RSs and CT. Time-varying of RMSSD for successive 30 s segments during the 10 min recovery period showed lower values for SSGs than CT for all tested points; the progressive increase in the beat-to-beat interval was similar for all interventions. In conclusion, SSGs caused the greatest post-exercise vagal disruption and it is likely that CT is the exercise modality that least delays over-all recovery. These results might help coaches design better training sessions by understanding athletes’ recovery status after completing their conditioning exercises.

Key words

  • autonomic nervous system
  • recovery
  • exercise modality
Accesso libero

Acute Hormonal Responses to High-Intensity Interval Training in Hyperoxia

Pubblicato online: 21 Jul 2020
Pagine: 125 - 134

Astratto

Abstract

This study aimed to compare selected hormonal responses to a single session of high intensity interval training performed with an increased fraction of inspired oxygen (hyperoxia) and under normoxic conditions. Twelve recreationally trained men (age 24 ± 3 years) performed two sessions of high intensity interval training on a cycle ergometer, in randomized order with hyperoxia (4 L·min-1 with a flowrate of 94% O2) and normoxia. Each session consisted of 5 intervals of 3 minutes at 85% of the maximal power output, interspersed by 2 min at 40% of the maximal power output. Serum cortisol, prolactin and vascular endothelial growth factor (VEGF) were assessed both before and immediately after each high intensity interval training session. Statistically significant differences in cortisol were found between hyperoxic and normoxic conditions (p = 0.011), with a significant increase in hyperoxia (61.4 ± 73.2%, p = 0.013, ES = -1.03), but not in normoxia (-1.3 ± 33.5%, p > 0.05, ES = 0.1). Prolactin increased similarly in both hyperoxia (118.1 ± 145.1%, p = 0.019, ES = -0.99) and normoxia (62.14 ± 75.43%, p = 0.005, ES = -0.5). VEGF was not statistically altered in either of the conditions. Our findings indicate that a single session of high intensity interval training in low-dose hyperoxia significantly increased cortisol concentrations in recreationally trained individuals compared to normoxia, while the difference was smaller in prolactin and diminished in VEGF concentrations.

Key words

  • HIIT
  • FO
  • hormones
  • Cortisol
  • VEGF
Accesso libero

Does Photobiomodulation Therapy Enhance Maximal Muscle Strength and Muscle Recovery?

Pubblicato online: 21 Jul 2020
Pagine: 135 - 144

Astratto

Abstract

Photobiomodulation has been shown to improve tissue and cell functions. We evaluated the influence of photobiomodulation, using a B-Cure laser, on: 1) maximal performance, and 2) muscle recovery after resistance exercise. Two separate crossover randomized double-blinded placebo-controlled trials were conducted. Sixty healthy physical education students (28 men, 32 women), aged 20-35, were recruited (30 participants for each trial). Participants performed two interventions for each experiment, with real lasers (GaAlAs, 808 nm) on three quadricep locations in parallel (overall treatment energy of ~150J) or sham (placebo) treatment. In the first experiment muscle total work (TW) and peak torque (PT) were measured by an isokinetic dynamometer in five repetitions of knee extension, and in the second experiment muscle recovery was measured after the induction of muscle fatigue by evaluating TW and PT in five repetitions of knee extension. There were no differences between treatments (real or sham) regarding the TW (F(1,28) = 1.09, p = .31), or PT (F(1,29) = .056, p = .814). In addition, there was no effect of photobiomodulation on muscle recovery as measured by the TW (F(1,27) = .16, p = .69) or PT (F(1,29) = .056, p = .814). Applying photobiomodulation for 10 min immediately before exercise did not improve muscle function or muscle recovery after fatigue.

Key words

  • fatigue
  • acute exercise
  • skeletal muscles
  • anaerobic power

Section III – Sports Training

Accesso libero

A Comparison Between the Squat and the Deadlift for Lower Body Strength and Power Training

Pubblicato online: 21 Jul 2020
Pagine: 145 - 152

Astratto

Abstract

The aim of this study was to compare the effects of two resistance training programs including either a deadlift or a parallel squat on lower body maximal strength and power in resistance trained males. Twenty-five resistance trained men were randomly assigned to a deadlift group (DE; n = 14; age = 24.3 ± 4.1 y; body mass = 84.8 ± 14.2 kg; body height = 180.3 ± 6.8 cm) or to a squat group (SQ; n = 11; age = 22.3 ± 1.6 y; body mass = 83.0 ± 13.6 kg; body height 179.9 ± 6.1 cm). Both groups trained 3 times per week for 6 weeks. The deadlift and the squat were the only lower body maximal strength exercises performed by DE and SQ groups, respectively, while both training programs included jumps. A significantly (p = 0.017) greater increase in deadlift 1RM was observed in the DE compared to the SQ group, while the SQ group obtained a significantly (p = 0.049) greater increase in squat 1RM. A significant increase in jump performance (p = 0.010), without significant interactions between groups (p = 0.552), was observed in both groups. Three participants of the DE group developed lower back pain and were excluded from the study. Results indicate that both the squat and the deadlift can result in similar improvement in lower body maximal strength and jump performance and can be successfully included in strength training programs. The incidence of back pain in the DE group may suggest a marked stress of this exercise on the lower back. Proper technique should be used to minimize the risk of injury, especially when the deadlift is performed.

Key words

  • resistance training
  • jump performance
  • strength exercises
Accesso libero

Set-to-set Performance Variation in Tennis Grand Slams: Play with Consistency and Risks

Pubblicato online: 21 Jul 2020
Pagine: 153 - 163

Astratto

Abstract

The study analysed the set-to-set variation in performance using match statistics of 146 completed main-draw matches in Australian Open and US Open 2016-2017 men’s singles. Comparisons of technical-tactical and physical performance variables were done between different sets; and the within-match coefficients of variation (CV) of these variables were contrasted between match winning and losing players. All comparisons were realized via standardized (Cohen’s d) mean differences and uncertainty in the true differences was assessed using non-clinical magnitude-based inferences. Results showed that there was possibly to very likely decreases in the serve, net and running related variables (mean difference, ±90%CL: -0.16, ±0.14 to -0.45, ±0.24, small) and an increase in the return and winner related variables (0.17, ±0.24 to 0.24, ±0.14, small) in the last sets when compared to the initial sets, indicating the influence of match fatigue and the player’s choice of match tactics and pacing strategy. Besides, winning players were revealed to have lower CV values in most of performance variables (-0.16, ±0.24 to -0.82, ±0.23, small to moderate) except for the second serve, winner, and physical performance variables (0.25, ±0.26 to 1.6, ±0.25, small to large), indicating that they would sacrifice the consistency to gain more aggressiveness and to dominate the match.

Key words

  • performance profile
  • match statistics
  • analysis
  • winner
Accesso libero

How do Elite Soccer Teams Perform to Ball Recovery? Effects of Tactical Modelling and Contextual Variables on the Defensive Patterns of Play

Pubblicato online: 21 Jul 2020
Pagine: 165 - 179

Astratto

Abstract

Researchers in soccer match analysis have been using limited procedures to express the dynamics of the game and mainly focus on the attack. Therefore, the aims of this paper were to detect the successful teams’ ball recovery defensive patterns of play and study the influence of tactical modelling, halves, match status, opponent quality and stage competition on those patterns. The sample consisted of 1323 situations of defensive ball possession of the semi-finalist teams from the 2014 FIFA World Cup play-offs, which was collected by a valid and reliable observational instrument (Soccer-Defence). The Kruskal-Wallis H, Mann-Whitney U, Chi-square, Z-, multinomial logistic regression tests and sequential analysis (p < .05; z > 1.96) were used accordingly to test the differences and associations among and within teams of tactical modelling, tactical-technical behaviours and contextual variables to ball recovery. We found that among teams ball recovery differed in duration; H(3) = 14.958, p = .002. Germany were more likely to perform ball recovery by the goalkeeper than Argentina (p = .04; OR = 0.47) or the Netherlands (p < .05; OR = 0.50). Nevertheless, Brazil was the least likely to concede a shot off goal. Teams facing lower-ranked opponents were 0.63 times less likely to perform ball recovery by interception (p <.001). Additionally, sequential analysis illustrated that teams varied between central and lateral high-pressure zones before ball recovery in lower zones of the field. Finally, coaches could use such findings to design training exercises, create their own style of play, and set strategies.

Key words

  • match analysis
  • defensive phase
  • tactics
  • style of play
  • multinomial logistic regression
  • sequential analysis
Accesso libero

Effects of Resisted vs. Conventional Sprint Training on Physical Fitness in Young Elite Tennis Players

Pubblicato online: 21 Jul 2020
Pagine: 181 - 192

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Abstract

This study aimed to compare the effects of 6-week resisted sprint (RST) versus conventional (unresisted) sprint training (CG) on sprint time, change of direction (COD) speed, repeated sprint ability (RSA) and jump performance (countermovement jump (CMJ) and standing long jump (SLJ)) in male young tennis players. Twenty players (age: 16.5 ± 0.3 years; body mass: 72.2 ± 5.5 kg; body height: 180.6 ± 4.6 cm) were randomly assigned to one of the two groups: RST (n = 10) and CG (n = 10). The training program was similar for both groups consisting of acceleration and deceleration exercises at short distances (3-4 m), and speed and agility drills. The RST group used weighted vests or elastic cords during the exercises. After 6 weeks of intervention, both training regimes resulted in small-to-moderate improvements in acceleration and sprint ability (5, 10, 20 m), SLJ and CMJ performances, COD pivoting on both, the non-dominant (moderate effect) and the dominant (small effect) foot, and the percentage of decrement (small effects) during a RSA test. Between-group comparisons showed that the SLJ (Δ = 2.0%) and 5 m sprint time (Δ = 1.1%) improved more in the RST group compared with the CG group. This study showed that 6 weeks of RST or unresisted training are time-efficient training regimes for physical improvements in young male tennis players.

Key words

  • young athletes
  • sprint performance
  • tennis
  • power
Accesso libero

A Comparison of Incremental Running Field and Treadmill Tests in Young Soccer Players

Pubblicato online: 21 Jul 2020
Pagine: 193 - 201

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Abstract

The purpose of this study was to compare the incremental running tests performed by young soccer players on a treadmill (Tr) and in the field (FTcod: 100 m change of direction and FTcir: 100 m circle). Nineteen players (average age 17.4 ± 1.1 years; body height 172.0 ± 5.7 cm; body mass 68.9 ± 6.7 kg) volunteered to perform incremental Tr , FTcod and FTcir running tests. In all three tests, players ran for 3 min at 8, 10, 12 and 14 km∙h-1 and were given a 1 min rest interval between subsequent stages. Blood lactate concentrations (La-) were measured at 1 min rest intervals and the heart rate (HR) responses of players were recorded during the tests. After a 5 min recovery period, the second part of the test started; players ran at 15 km∙h-1 with velocity increments of 1 km∙h-1 every 1 min until exhaustion. This part was performed to determine maximum HR, maximum La- and the players’ final velocities. The results showed that players had significantly lower La- (F = 6.93, p = 0.07, η2 = 0.46, 95%CI(TR-FTcir) = -1.91/-0.34, 95%CI(TR-FTcod) = -1.59/-0.05) and HR (F = 9.08, p = 0.02, η2 = 0.53, 95%CI(TR-FTcir) = -6.98/-1.68, 95%CI(TR-FTcod) = -7.19/1.08) responses in the Tr test than in the FTcir and FTcod tests at 14 km∙h-1. It was also found that players completed the Tr test (F = 58.22, p = 0.00, η2 = 0.87) at higher final running velocities than the FTcir (95%CI(TR-FTcir) = 1.67/2.78) and FTcod (95%CI(TR-FTcod) = 1.69/2.85) tests. In conclusion, when coaches or sports scientists plan to train at higher running velocities or according to the final velocity in the test, it is advisable to carry out testing in the circumstances under which training will be carried out (in the field or on a treadmill).

Key words

  • heart rate
  • running velocity
  • blood lactate
  • running tests
Accesso libero

Differentiating African Teams from European Teams: Identifying the Key Performance Indicators in the FIFA World Cup 2018

Pubblicato online: 21 Jul 2020
Pagine: 203 - 208

Astratto

Abstract

Soccer is the most popular sport in the world. Despite this global popularity, European teams in contrast to African ones, have dominated the Fédération Internationale de Football Association (FIFA) World Cup tournaments for many decades. Therefore, the aim of this study was to examine the performance indicators that differentiated between African and European teams in the 2018 FIFA World Cup. Thirty matches played by five European (n = 15) and five African teams (n = 15) from the group stages of the World Cup were analysed using the InStat video system. The results showed that European teams had higher averages than African teams on the following performance variables: total shots, shots on target, goals scored from open play and set pieces, ball possession, short passes, medium passes, total passes, accurate passes and corner kicks. Therefore, soccer coaches should take note of these findings as they could serve as a benchmark for African teams to set trends and improve their performance at FIFA World Cup tournaments.

Key words

  • performance
  • tactics
  • set-play
  • open-play
  • goals
  • competition
Accesso libero

Evidence for the Relative Age Effect in the Spanish Professional Soccer League

Pubblicato online: 21 Jul 2020
Pagine: 209 - 218

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Abstract

The concept of the relative age effect refers to the consequences of the physical and psychological differences that may exist between those born earlier or later within the same calendar year. The objective of the present study was to examine this phenomenon in Spanish professional soccer, identifying the influences of the competitive level and the club of origin. The sample comprised 2,130 individuals from five competitive categories: under 12 (U12; n = 480), under 14 (U14; n = 338), under 16 (U16; n = 390), under 19 years old (U19; n = 489) and professional players (n = 433), with nine teams from the Spanish professional soccer league (PSL). Statistical analysis was based on a chi-squared test followed by calculation of the odds ratios and 95% confidence intervals. The main results show that at all levels of competition there was over-representation of individuals born in the first few months of the year. By clubs, the same over-representation was observed. It may be concluded that the relative age effect is consistent and exists throughout Spanish soccer, whether at youth or professional levels. An analysis by age categories showed a more pronounced effect in those competitions in which the youngest players participate, while in clubs the effect continued to be significantly present in all cases investigated in the study.

Key words

  • birth quarter
  • talent identification
  • potential
  • team sport games
Accesso libero

Effects of Training with an Agility Ladder on Sprint, Agility, and Dribbling Performance in Youth Soccer Players

Pubblicato online: 21 Jul 2020
Pagine: 219 - 228

Astratto

Abstract

The aim of this study was to examine the effects of coordination training using an agility ladder compared with a control group on physical fitness and technical performance in youth soccer players. Eighteen male youth soccer players (age: 12.2 ± 0.4 years; body height: 158.3 ± 10.8 cm; body mass: 45.0 ± 8.0 kg) were randomly assigned to an agility ladder group (n = 10) or a control group (n = 8). The intervention program was carried out three times a week over six weeks. Before and after the training period, the 10 m sprint, 20 m sprint, dribbling speed test, agility test, and slalom dribbling test performances were assessed. Within-group analysis showed significant improvements (p < 0.005) in 10 m and 20 m sprint performance from the pre- to the post-test for the agility ladder group (-2.39% and -2.10%) and the control group (-2.54% and -1.44%). No significant differences (p > 0.005) were found from the pre- to the post-test in the dribbling speed test, agility test, slalom dribbling test, and skill index. In the between-group analysis, there were no differences between the agility ladder group and the control group in any variable. In conclusion, the findings of this study suggest coordination training with an agility ladder does not seem to be effective to improve physical fitness and dribbling. Therefore, this information could be beneficial to players and coaches for programming tasks during soccer training sessions.

Key words

  • team sports
  • physical performance
  • physical training
Accesso libero

Prediction of Handball Players' Performance on the Basis of Kinanthropometric Variables, Conditioning Abilities, and Handball Skills

Pubblicato online: 21 Jul 2020
Pagine: 229 - 239

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Abstract

Handball (team handball) is a multifactorial sport. The aims of this study were (i) to analyse anthropometric variables, conditioning abilities, and handball skills in club handball players according to age and sex, and (ii) to develop multivariate models explaining club handball performance from a multidimensional perspective. Two hundred and twenty six handball players (age 16.9 ± 4.0 years, 54% males) participated in the study. The players belonged to under-14, under-16, under-19, and A teams. They were evaluated with a battery of 18 tests covering kinanthropometry, conditioning abilities, and handball skills. A one-way ANOVA with a Bonferroni post-hoc test was used to investigate differences between teams, and a t-test for differences between the sexes. For each team, a discriminant analysis was performed to determine differences between performance levels. The results showed little differences between the U19 and A teams in any of the variables studied in either men or women, and that the lowest values corresponded to the U14 team. The differences according to sex were clear in the kinanthropometric and conditioning variables, but much less so in handball skills. The eight multivariate models that were constructed classified successfully from 48.5 to 100% of the sample using at most three variables (except for the women's A team whose model selected six variables). Conditioning variables were most discriminating in men, and handball skills in women. This would seem to reflect the different performance profiles.

Key words

  • power
  • endurance
  • speed
  • velocity
  • team sports games
Accesso libero

Actual Playing Time of Water Polo Players in Relation to the Field Position

Pubblicato online: 21 Jul 2020
Pagine: 241 - 249

Astratto

Abstract

In water polo competitions, teams play four periods, each period consisting of eight minutes of actual playing time: a total of 32 minutes (Standard Actual Play Time, SAPT). Substitutions are permitted and a player may be substituted several times. The aim of this article was to provide reference data on played time, taking into consideration the field play position of the players. 352 male water polo players of 18 different nationalities were studied during two consecutive FINA World Championships. 180 games were analyzed and 1980 measurements of the game Measured Actual Play Time (MAPT) were taken. A time density index (DI) was calculated for each athlete using SAPT and MAPT. No statistically significant differences between the field positions were found with regard to age, as was the case in relation to teams between Game MAPT, Tournament MAPT and DI. However, when looking at the diverse field positions (field players, FP; center forward, CF; center back, CB), there were statistically significant differences: Game MAPT FPvsCB p = 0.03 and FPvsCF p = 0.03; Tournament MAPT FPvsCB p = 0.03; DI FPvsCB p = 0.03 and FPvsCF p = 0.04. In these competitions the water polo player had on average a MAPT value of 17.4 ± 6.1 min (54.6 ± 9.5% DI); there were athletes who played 2.3 min (7.1% DI) and others who played up to 31.6 min (95.3% DI). The MAPT in water polo is extremely variable among athletes and must be considered for a correct performance analysis. High-level water polo players require different training strategies depending on their MAPT.

Key words

  • match analysis
  • field position
  • age
  • periodization
  • training strategies

Section IV – Medical Issues of Sport and Eercise

Accesso libero

Does Oxygen Uptake Before Physical Exercise Affect Tear Osmolarity?

Pubblicato online: 21 Jul 2020
Pagine: 297 - 304

Astratto

Abstract

Recently, it has been reported that tear osmolarity (Tosm) is correlated with plasma osmolarity and will increase during exertion. We aimed to assess whether inhaling oxygen-enriched air between exercises could significantly change the Tosm value. Thirty men aged 24.9 years were included in the study. A cycloergometer was used to perform the exercise protocol. We recorded the participants’ Tosm (mOsm/L), heart rate (HR, beats/minute), oxygen saturation, and blood pressure values. After the first exhaustive exercise (T1), participants inhaled oxygen in the experimental group and a placebo in the control group. After the second exercise (T2), another set of measurements was obtained. The Tosm value before exercise was 297.4 ± 1.21 and 296.53 ± 1.11 mOsm/L (p = 0.61718) and the HR was 72.6 ± 2.59 and 73 ± 2.59 beats/minute (p = 0.39949) in the study and the control group, respectively. At T1, Tosm was 303.67 ± 1.25 and 302.2 ± 1.25 mOsm/L (p = 0.41286) and the HR reached 178.04 ± 2.60 and 176.4 ± 2.60 beats/minute (p = 0.65832), respectively. At T2, Tosm in the study group reached 305.73 ± 0.86 mOsm/L (correlation with the use of oxygen: r = −0.3818), and in the control group, it was 308.4 ± 0.86 mOsm/L (p = 0.0373), while the HR reached 172.20 ± 2.53 beats/minute in the study group and 178.2 ± 2.53 beats/minute in the control group (p = 0.057). It was concluded that inhaling oxygen before and after exercise could increase the rate of recovery after exhaustive exercise.

Key words

  • tearing
  • body water
  • sport
  • lacrimation
  • TearLab
  • Tosm
Accesso libero

Prevalence of Injuries in Exercise Programs Based on Crossfit®, Cross Training and High-Intensity Functional Training Methodologies: A Systematic Review

Pubblicato online: 21 Jul 2020
Pagine: 251 - 265

Astratto

Abstract

Current literature shows studies that question the safety of the practices carried out in high-intensity training modalities such as CrossFit®, Cross Training or High-Intensity Functional Training, which may lead to a greater risk in the prevalence of injuries. The aim of this study was to analyze in detail the prevalence of injuries occurring in training based on the CrossFit®, Cross Training or High-Intensity Functional Training modalities, through a systematic review, as well as evaluating the methodological quality of the included studies. We used the recommendations of the PRISMA protocol. For the quality analysis of the studies, we applied the tool proposed by the National Institute of Health (United States). The areas that mainly present a higher risk of injury during CrossFit, Cross Training or High-Intensity Functional Training practices are shoulders, knees and back. Additionally, 11 of the 12 included studies displayed a poor methodological quality according to the quality tool used.

Key words

  • training
  • high-intensity
  • sports injuries
  • gym
  • cross training
Accesso libero

Mini-Basketball Training Program Improves Physical Fitness and Social Communication in Preschool Children with Autism Spectrum Disorders

Pubblicato online: 21 Jul 2020
Pagine: 267 - 278

Astratto

Abstract

This investigation examined the effects of a 12-week mini-basketball training program (MBTP) on physical fitness and social communication in preschool children with autism spectrum disorders (ASD). The study applied a quasi-experimental design. Fifty-nine preschool children aged 3-6 years with ASD were assigned to either a MBTP group (n = 30) or a control group (n = 29). Participants in the MBTP group received a scheduled mini-basketball training program (5 sessions per week, forty minutes per session) for twelve consecutive weeks, while the control group was instructed to maintain their daily activities. The physical fitness test and the parent-reported Social Responsiveness Scale Second Edition (SRS-2) test were performed before and after the intervention. Results indicated that the 12-week MBTP facilitated performance in the physical fitness test, particularly in speed-agility and muscular strength abilities. Additionally, children in the MBTP group demonstrated improvement in SRS-2 performance in social awareness, social cognition, social communication, and autistic mannerisms, whereas no such changes were found in the control group. It may be concluded that the 12-week MBTP could improve physical fitness and social communication in preschool children with ASD, and thus the use of physical exercise intervention as a therapeutic tool for preschoolers with ASD is recommended.

Key words

  • mini-basketball
  • physical fitness
  • social communication
  • preschool children
  • autism spectrum disorders
  • quasi-experimental

Section IV – Behavioural Sciences in Sport

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Prevalence of Urinary Incontinence in High-Impact Sport Athletes: A Systematic Review and Meta-Analysis

Pubblicato online: 21 Jul 2020
Pagine: 279 - 288

Astratto

Abstract

The aim of this study was to systematize the scientific evidence that assessed the prevalence of urinary incontinence in female athletes and determine which modality is most predisposed to stress urinary incontinence. From September to December 2018, a systematic literature search of current interventional studies of stress urinary incontinence of the last ten years was performed using PubMed, EMBASE, Scopus and Web of Science databases. The methodological quality was assessed by the Downs and Black scale, while the data collected from the studies were analyzed through meta-analysis. Nine studies met the eligibility criteria, meaning they included reports of urinary incontinence in different sports. The meta-analysis showed 25.9% prevalence of urinary incontinence in female athletes in different sports, as well as 20.7% prevalence of stress urinary incontinence. The most prevalent high impact sport was volleyball, with the value of 75.6%. The prevalence of urinary incontinence can be high in female athletes, with high-impact sports potentially increasing the risk for stress urinary incontinence. Further research is needed regarding the potential risk factors related to the onset of urinary incontinence.

Key words

  • exercise
  • female athletes
  • pelvic floor muscle
  • stress urinary incontinence
Accesso libero

Effects of High-Velocity Strength Training on Movement Velocity and Strength Endurance in Experienced Powerlifters with Cerebral Palsy

Pubblicato online: 21 Jul 2020
Pagine: 235 - 243

Astratto

Abstract

The present study aimed to evaluate the effects of a 6-week high-velocity strength training (HVST) intervention on movement velocity and strength endurance in experienced powerlifters with cerebral palsy (CP). Eleven experienced powerlifters with CP and seven from a control group (CON), were subjected to 6-week HVST. An assessment of movement velocity and strength endurance was conducted one week before (T1) and one week after (T2) the 6-week training intervention. During testing, athletes performed a maximum number of bench press repetitions possible within 5 sets of 15 s each, with 1-min passive rest intervals in-between. The indicator of movement velocity was the weight pressed in the first 5 s (5sW) in all performed sets. Strength endurance was described by the total weight (TW) pressed during the test. 5sW in T2 was significantly higher as compared with T1 in the CP group only (T1 928.9 ± 342.9 kg vs. T2 1007.3 ± 324.6 kg; p = 0.016). TW in T2 was significantly higher as compared with T1, both in the CP group (T1 2550.5 ± 843.9 kg vs. T2 2809.8 ± 981.3 kg; p < 0.001) and in the CON group (T1 2300.7 ± 845.1 kg vs. T2 2468.9 ± 890.1 kg; p = 0.049). A 6-week program of HVST increased movement velocity in resistance trained CP athletes. The gains of strength endurance were observed in both groups.

Key words

  • performance
  • disabled athletes
  • resistance exercise
  • resistance
28 Articoli

Section I – Kinesiology

Accesso libero

Push-Ups are Able to Predict the Bench Press 1-RM and Constitute an Alternative for Measuring Maximum Upper Body Strength Based on Load-Velocity Relationships

Pubblicato online: 21 Jul 2020
Pagine: 7 - 18

Astratto

Abstract

The aims of this study were firstly to compare the similarity in upper-body muscle activation between the bench press and push-up at similar loads, and secondly to establish a 1-RM prediction equation between the two exercises based upon the load-velocity relationship. Twenty resistance-trained male athletes (age 22.5 ± 5.24 years, body mass 83.7 ± 10.7 kg, body height 1.80 ± 0.06 m) performed push-ups and bench presses with four different loads. Push-ups were performed without a weight vest and with a 10-20-30 kg weight vest. Bench presses were performed at 50-80% of athletes’ assumed 1 repetition max (1-RM) in 10 kg steps, while a linear encoder measured performance during the exercises. A load-velocity relationship was established as a product of the load and velocity for the push-up and bench press per participant and the equation was used to establish a predicted 1-RM. Mean muscle activation of eight upper body muscles was recorded for each exercise and each load. The main findings of this study demonstrate an extremely large association between the predicted 1-RM loads performed with the push-up and bench press (r = 0.93) in experienced resistance trained men. Furthermore, most muscles showed similar activations between the two exercises with the different loads except the deltoid and biceps brachii muscles. It may be concluded that it is possible to predict a cross-over 1-RM between the two exercises based upon the load-velocity relationship in each exercise, and that training push-ups largely targets the same muscles as the bench press except the deltoid and biceps muscles. For coaches and athletes, the use of this method is a low cost and time-effective alternative for standard 1-RM bench press testing to predict maximal upper body strength.

Key words

  • mean velocity
  • resistance training
  • strength
  • upper-body
Accesso libero

The Applications of Landing Strategies in Badminton Footwork Training on a Backhand Side Lateral Jump Smash

Pubblicato online: 21 Jul 2020
Pagine: 19 - 31

Astratto

Abstract

Previous research in badminton has associated unilateral landings following overhead strokes with the occurrence of knee injuries. Smashing involves tensing the abdomen muscles while swinging the racket rapidly and maintaining one’s balance while performing coordinated movements and steps; this process puts stress on the player’s lower limbs. However, few studies have compared the effects of different stroke training while performing various types of badminton strokes. This study investigated the influence of different stroke training on the smash action of badminton players. Three stroke training conditions were considered: shadow, target striking, and smashing. Sixteen male experienced badminton players were recruited for this study. One-way repeated-measures ANOVA with Bonferroni correction was used to identify the differences. At the initial contact with the ground, the knee flexion and knee valgus angles under the smash condition were significantly higher than target and shadow conditions. Under the smash condition, hip abduction was significantly higher than under the target and shadow conditions. Moreover, the hip abduction under the target condition was significantly higher than under the shadow condition. At the maximum knee flexion, the hip abduction under the smash and target conditions was significantly higher than under the shadow condition. Regarding the time from the moment of initial contact to the peak of vertical ground reaction force it was shorter under the smash condition than the target and shadow conditions. The vertical ground reaction force was higher under the smash condition than under the target and shadow conditions. The 50 ms impulse was higher under the smash condition than under the target and shadow conditions. The main findings of this study are that under the smash condition, the motion in the frontal plane increased, which produced higher loads on the joints in the lower limbs. Player performed the same footwork under the three conditions, but the landing strategies differed because of unique swing motions and techniques. The condition under which a player hits a shot to a target area can affect the landing. The results of this study suggest that target practice is more effective for improving the landing technique employed during actual shots than shadow practice.

Key words

  • motion analysis
  • footwork training
  • lateral jump smash
Accesso libero

The Effects of Altering the Concentric/Eccentric Phase Times on EMG Response, Lactate Accumulation and Work Completed when Training to Failure

Pubblicato online: 21 Jul 2020
Pagine: 33 - 44

Astratto

Abstract

This study compared the electromyographic response, the blood lactate concentration (BLC), and the maximum number of repetitions (MNR) between protocols of different concentric/eccentric duration taken to muscle failure. This comparison may help to understand how different concentric/eccentric duration may influence performance and the central and metabolic responses in trained men. Seventeen strength-trained men performed two protocols in a counterbalanced design. Three sets of the Smith bench press exercise were performed to failure at 60% of the one-repetition maximum (1RM) using each protocol (4-s concentric/2-s eccentric [4 s: 2 s]; and 2-s concentric/4-s eccentric [2 s: 4 s]). The normalized root mean square (EMGRMS) and the mean frequency (EMGMF) of the electromyographic signals for the pectoralis major and the triceps brachii were compared in the first, middle, and last repetitions. The BLC was assessed at rest, during and after the test sessions. To compare the EMG and BLC, a 3-way ANOVA with repeated measures with a post hoc Tukey’s test was used. To compare the MNR performed across the sets, an ANOVA-type rank test with the Dunn’s post hoc test was used. The ANOVA indicated a greater EMGRMS for Protocol 4 s: 2 s in the pectoralis major and a lower EMGMF for Protocol 4 s: 2 s in the triceps brachii at the middle and last repetitions. Both protocols increased the EMGRMS and decreased the EMGMF across repetitions. Despite the results show different levels of activation and neuromuscular fatigue between protocols, the BLC and the MNR were similar.

Key words

  • physiology
  • strength
  • electromyography
  • bench press
  • central fatigue
Accesso libero

The Reactive Bounding Coefficient as a Measure of Horizontal Reactive Strength to Evaluate Stretch-Shortening Cycle Performance in Sprinters

Pubblicato online: 21 Jul 2020
Pagine: 45 - 55

Astratto

Abstract

Plyometric exercises such as drop jumping and bounding offer athletes a substantiated means of enhancing athletic performance. Between the two exercises, reactive measurement using bounding (reactive bounding coefficient [RBC]) has received scant attention within the domain of training and conditioning. Therefore, this study aimed to identify the viability of utilising a speed-bounding exercise to assess horizontal reactive strength. Eleven young, male elite sprinters (age: 17.8 ± 1.3 yr; body height: 1.72 ± 0.06 m; body mass: 66.05 ± 6.10 kg; best 100 m sprint time: 10.77 ± 0.32 s) were tested for static jumps (SJ), drop jumps (DJ), 10 speed-bounding (RBC10), and 50 m sprint performance. Between-group comparisons based on sprint ability (fast [FSG] vs. slow [SSG] sprint-group) and correlation coefficients were computed subsequently. The FSG (n = 5; 50 m time: 5.82 ± 0.11 s; RBC10: 7.46 ± 0.27) performed significantly better in the RBC10 (p = 0.036) than the SSG (n = 5; 50 m time: 6.09 ± 0.13 s; RBC10: 7.09 ± 0.25). A very high correlation was attained between the RBC10 and the criterion measure, the SJ (r = 0.83). Additionally, RBC10 appeared to be correlated with 30, 50, 10-30 and 30-50 m sprint times (r = -0.52 to -0.60). This positive trend, however, was not observed for the DJ reactive strength index (trivial to moderate correlations). Good reliability was shown for the RBC10 and all sprint distances (“1.5% coefficient variation). Furthermore, all sprinters attained ground contact times of 0.12-0.18 s during the RBC10 which was indicative of fast stretch-shortening cycles during movement, suggesting that the RBC10 could be utilised to assess plyometric ability and enhance sprint performance. Overall, the RBC10 seems able to discriminate between the FSG and the SSG, indicating it has acceptable levels of validity and reliability.

Key words

  • athletics
  • explosive
  • plyometric
  • power
  • speed-strength
  • sprinting
Accesso libero

Kinematic Mobile Drop Jump Analysis at Different Heights Based on a Smartphone Inertial Sensor

Pubblicato online: 21 Jul 2020
Pagine: 57 - 65

Astratto

Abstract

The purpose of this study was to describe the acceleration variables in a plyometric jump test using the inertial sensor built into an iPhone 4S® smartphone, and the jumping variables from a contact mat. A cross-sectional study was conducted involving 16 healthy young adults. Linear acceleration, flight time, contact time and jump height were measured in a drop jump test from 60 cm and from 30 cm. Greater acceleration values were found in the drop jump test from 60 cm; the same was observed for the values from the contact mat. Multiple regression analysis was performed for each drop jump test: jump height was used as the dependent variable, and the most relevant variables were used as predictor variables (weight and maximum angular velocity in the Y axis for analysis of the drop jump from 60 cm, and weight and maximum acceleration in the Z axis for the drop jump from 30 cm). We found a significant regression model for the drop jump test from 60 cm (R2 = 0.515, p “ 0.001) and for the test from 30 cm (R2 = 0.460, p “ 0.01). According to the results obtained in this study, the built-in iPhone 4S® inertial sensor is able to measure acceleration for healthy young adults performing a vertical drop jump test. The acceleration kinematic variables are higher in the drop jump test from 60 cm than from 30 cm.

Key words

  • acceleration
  • biomechanics
  • physical performance
  • plyometric training
Accesso libero

A Finite Element Model for Estimation of Contact Dynamics During a Jumping Movement on a Trampoline

Pubblicato online: 21 Jul 2020
Pagine: 59 - 72

Astratto

Abstract

In order to fully understand contact dynamics on a trampoline, a simulation approach using a musculoskeletal model coupled with a dynamic model of the trampoline is essential. The purpose of the study was to examine dynamics and selected lower extremity muscle forces in a landing and jumping movement on a trampoline, using a combination of finite element modeling and musculoskeletal modeling. The rigid frame of the trampoline was modeled in ADAMS and coupled with a finite element model of the elastic trampoline net surface in ANSYS. A musculoskeletal model of an elite trampoline athlete was further developed in LifeMod and combined with the finite element model of the trampoline. The results showed that the peak trampoline reaction forces (TRF) were 3400 N (6.6 BW) and 2900 N (5.6 BW) for the left and right limb, respectively. The right hip, knee and ankle joint reaction forces reached the maximum between 3000-4000 N (5.8 – 7.7 BW). The gluteus maximum and quadriceps reached the maximum muscle force of 380 N (0.7 BW) and 780 N (1.5 BW), respectively. Asymmetric loading patterns between left and right TRFs and lower extremities joint reaction forces were observed due to the need to generate the rotational movement during the takeoff. The observed rigid and erect body posture suggested that the hip and knee extensors played important roles in minimizing energy absorption and maximizing energy generation during the trampoline takeoff.

Key words

  • trampoline
  • finite element model
  • musculoskeletal model
  • landing technique

Section II – Exercise Physiology & Sports Medicine

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Circulating Inflammatory Biomarkers and Endocrine Responses to Exercise in Female Soccer Players

Pubblicato online: 21 Jul 2020
Pagine: 73 - 82

Astratto

Abstract

The objective of the study to determine the effects of graded exercise on the cytokines and insulin-like growth factor-1 (IGF-1), growth hormone (hGH), testosterone (T), and cortisol (C) concentrations in the peripheral blood of female soccer players, and to evaluate if increased inflammatory biomarkers were related to these hormones and performance variables. Sixteen female soccer players (N = 16, age 19.3 ± 2.3 years) participated in this study. Blood samples were collected at three time points: pre-exercise, post-exercise, and in the 15th minute of recovery, to evaluate morphological and biochemical variables. The relative expression of IL-6 (interleukin 6) and serum concentrations of the cytokines were increased in the recovery period compared to pre-exercise levels (p = 0.03 and p=0.005, respectively). There was a significant effect of exercise on serum hGH level (p “ 0.001), T/C ratio (p = 0.001), and C level (p=0.02). Positive correlations were found between: post-exercise IL-1β (interleukin 1 beta) and IL-6 (R = 0.84, p = 0.000), and the IL-6 and TNF-α (tumor necrosis factor alpha) gene expression during recovery (R = 0.65, p = 0.009), and serum IL-1β post-exercise and maximal power (R = 0.68; p = 0.004). Exercise-induced serum C levels positively correlated with IGF-1 levels (R = 0.52 p = 0.05). Negative associations were revealed between post-exercise T/C ratio and IGF-1 (R = - 0.58, p = 0.03) and serum free T and IL- β (R = -0.56, p = 0.04) levels. The low level of pre-exercise genes and protein of the IL-1β, IL-6 and TNF-α indicate a lack of inflammation signs in the female soccer players. This study shows significant effects of exercise on hormone levels and pro-inflammatory markers, which could be used to identify the role of female sex steroids on the immune function.

Key words

  • cytokine
  • hormones
  • female soccer players
  • exercise performance
Accesso libero

Analysis of Morphofunctional Variables Associated with Performance in Crossfit® Competitors

Pubblicato online: 21 Jul 2020
Pagine: 83 - 91

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Abstract

CrossFit® is a competitive sport and fitness modality characterized by multiple physical capabilities and multi-joint movements. This study aimed to analyse and classify variables related to CrossFit® competitors’ specific performance. Fifteen male CrossFit® competitors were selected (n = 15; 30.57 ± 5.5 years; 1.76 ± 0.06 m; 78.55 ± 9.12 kg). Mean values were obtained for body mass index (25.3 ± 2.14 kg/m2), 4 skinfolds, 1 repetition maximum in the squat (137.60 ± 19.65 kg) and the bench press (101.67 ± 10.64 kg), maximum pull-ups (18.87 ± 5.05), sit-ups in 60 s (46.60 ± 4.22), peak power in the countermovement jump (3908.04 ± 423.68 W), VO2max with a shuttle run test (47.70 ± 4.79 ml kg-1·min-1), and time in the Workout of the Day (WOD) “Fran” (337.13 ± 119.19 s) and “Donkey Kong” (417.47 ± 98.44 s) components. Principal component analysis was conducted to classify variables and to select those most related to each new component (“strength and muscle mass”, “adiposity” and “aerobic capacity”). The correlation matrix was analysed, indicating significant correlations between “Donkey Kong” and VO2max (r = -.675; p “ .01), suprailiac skinfold (r = .713; p “ .01) and sit-ups (r = -.563; p “ .05); and between “Fran” and squat (r = -.528; p “ .05). Three important components characterizing CrossFit® competitors were identified: “strength and muscle mass”, low “adiposity” and “aerobic capacity”. Significant relationships between morphofunctional variables and Crossfit® performance were found in Crossfit® competitors.

Key words

  • high intensity interval training
  • power
  • principal component analysis
  • Crossfit
  • performance
Accesso libero

Reliability and Validity of Maximal Mean and Critical Speed and Metabolic Power in Australian Youth Soccer Players

Pubblicato online: 21 Jul 2020
Pagine: 93 - 102

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Abstract

The reliability and validity of maximal mean speed (MMS), maximal mean metabolic power (MMPmet), critical speed (CS) and critical metabolic power (CPmet) were examined throughout the 2016-2017 soccer National Youth League competitions. Global positioning system (GPS) data were collected from 20 sub-elite soccer players during a battery of maximal running tests and four home matches. A symmetric moving average algorithm was applied to the instantaneous velocity data using specific time windows (1, 5, 10, 60, 300 and 600 s) and peak values were identified. Additionally, CS and CP¬met values calculated from match data were compared to CS and CPmet values determined from previously validated field tests to assess the validity of match values. Intra-class correlation (one-way random absolute agreement) scores ranged from 0.577 to 0.902 for speed, and from 0.701 to 0.863 for metabolic power values. Coefficients of variation (CV) ranged from good to moderate for speed (4-6%) and metabolic power (4-8%). Only CS and CPmet values were significantly correlated (r = 0.842; 0.700) and not statistically different (p = 0.066; 0.271) to values obtained in a shuttle-running critical test. While the present findings identified match-derived MMS, MMPmet, CS and CPmet to be reliable, only CS and CPmet derived from match play were validated to a CS field test that required changes in speed and direction rather than continuous running. This suggests that both maximal mean and critical speed and metabolic power analyses could be alternatives to absolute distance and speed in the assessment of match running performance during competitive matches.

Key words

  • soccer
  • global positioning system
  • external load
Accesso libero

Can Heart Rate Variability Biofeedback Improve Athletic Performance? A Systematic Review

Pubblicato online: 21 Jul 2020
Pagine: 103 - 114

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Abstract

This systematic review was conducted to evaluate the effect of heart rate variability biofeedback (HRV BFB) on performance of athletes. Six electronic databases (Springerlink, SportDiscus, Web of Science, PROQUEST Academic Research Library, Google Scholar, and ScienceDirect) and article references were searched. Eligibility criteria were: 1. experimental studies involving athletes randomly allocated among groups (randomized control trial); 2. availability of HRV BFB as a treatment compared to a control condition (CON) that involves regular sport/dance training, a placebo (PLA) or other methods of BFB; 3. performance-related variables such as a dependent index; and, 4. peer-reviewed articles written in English. Out of 660 articles, six studies were included in the systematic review which involved 187 athletes (females: n = 89; males n = 98). Six studies compared HRV BFB with a CON, three studies compared HRV BFB with a PLA, and two studies differentiated HRV BFB with other methods of BFB. Findings support HRV BFB as a potential intervention to improve fine and gross motor function in athletes.

Key words

  • heart rate variability
  • biofeedback
  • athletes
  • performance
  • resonant frequency breathing
Accesso libero

Cardiac Parasympathetic Reactivation Following Small‐Sided Games, Repeated Sprints and Circuit Training in Elite Handball Players

Pubblicato online: 21 Jul 2020
Pagine: 115 - 124

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Abstract

To compare acute parasympathetic reactivation following usual training exercises, the acute post-exercise heart rate (HR) and heart rate variability (HRV) were analysed. Fourteen elite male handball players completed three separate sessions of 16-min small-sided games (SSGs), repeated sprints (RSs) consisting of two sets of six repetitions of a 25-m sprint with a 180° change of direction (12.5 m + 12.5 m) every 25 s and 40 min of handball-specific circuit training (CT, one brief action every 40 s). The HR was recorded during the exercises; HRV was assessed 10 min before and after exercise. The exercise HR was higher for SSGs than RSs and it was higher for RSs than CT. Comparison of the baseline and acute post-exercise HRV values showed that parasympathetic indices decreased following SSG (p < 0.01 – p < 0.0001; large effect size) and RS (p < 0.05 –p < 0.01; large effect size) interventions. For CT, recovery values remained similar to the baseline (small effect size). The comparison of the acute recovery period between exercise modalities showed that the root mean square of the successive differences (RMSSD) was lower for SSGs than RSs and CT. No difference in any HRV indices was observed between RSs and CT. Time-varying of RMSSD for successive 30 s segments during the 10 min recovery period showed lower values for SSGs than CT for all tested points; the progressive increase in the beat-to-beat interval was similar for all interventions. In conclusion, SSGs caused the greatest post-exercise vagal disruption and it is likely that CT is the exercise modality that least delays over-all recovery. These results might help coaches design better training sessions by understanding athletes’ recovery status after completing their conditioning exercises.

Key words

  • autonomic nervous system
  • recovery
  • exercise modality
Accesso libero

Acute Hormonal Responses to High-Intensity Interval Training in Hyperoxia

Pubblicato online: 21 Jul 2020
Pagine: 125 - 134

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Abstract

This study aimed to compare selected hormonal responses to a single session of high intensity interval training performed with an increased fraction of inspired oxygen (hyperoxia) and under normoxic conditions. Twelve recreationally trained men (age 24 ± 3 years) performed two sessions of high intensity interval training on a cycle ergometer, in randomized order with hyperoxia (4 L·min-1 with a flowrate of 94% O2) and normoxia. Each session consisted of 5 intervals of 3 minutes at 85% of the maximal power output, interspersed by 2 min at 40% of the maximal power output. Serum cortisol, prolactin and vascular endothelial growth factor (VEGF) were assessed both before and immediately after each high intensity interval training session. Statistically significant differences in cortisol were found between hyperoxic and normoxic conditions (p = 0.011), with a significant increase in hyperoxia (61.4 ± 73.2%, p = 0.013, ES = -1.03), but not in normoxia (-1.3 ± 33.5%, p > 0.05, ES = 0.1). Prolactin increased similarly in both hyperoxia (118.1 ± 145.1%, p = 0.019, ES = -0.99) and normoxia (62.14 ± 75.43%, p = 0.005, ES = -0.5). VEGF was not statistically altered in either of the conditions. Our findings indicate that a single session of high intensity interval training in low-dose hyperoxia significantly increased cortisol concentrations in recreationally trained individuals compared to normoxia, while the difference was smaller in prolactin and diminished in VEGF concentrations.

Key words

  • HIIT
  • FO
  • hormones
  • Cortisol
  • VEGF
Accesso libero

Does Photobiomodulation Therapy Enhance Maximal Muscle Strength and Muscle Recovery?

Pubblicato online: 21 Jul 2020
Pagine: 135 - 144

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Abstract

Photobiomodulation has been shown to improve tissue and cell functions. We evaluated the influence of photobiomodulation, using a B-Cure laser, on: 1) maximal performance, and 2) muscle recovery after resistance exercise. Two separate crossover randomized double-blinded placebo-controlled trials were conducted. Sixty healthy physical education students (28 men, 32 women), aged 20-35, were recruited (30 participants for each trial). Participants performed two interventions for each experiment, with real lasers (GaAlAs, 808 nm) on three quadricep locations in parallel (overall treatment energy of ~150J) or sham (placebo) treatment. In the first experiment muscle total work (TW) and peak torque (PT) were measured by an isokinetic dynamometer in five repetitions of knee extension, and in the second experiment muscle recovery was measured after the induction of muscle fatigue by evaluating TW and PT in five repetitions of knee extension. There were no differences between treatments (real or sham) regarding the TW (F(1,28) = 1.09, p = .31), or PT (F(1,29) = .056, p = .814). In addition, there was no effect of photobiomodulation on muscle recovery as measured by the TW (F(1,27) = .16, p = .69) or PT (F(1,29) = .056, p = .814). Applying photobiomodulation for 10 min immediately before exercise did not improve muscle function or muscle recovery after fatigue.

Key words

  • fatigue
  • acute exercise
  • skeletal muscles
  • anaerobic power

Section III – Sports Training

Accesso libero

A Comparison Between the Squat and the Deadlift for Lower Body Strength and Power Training

Pubblicato online: 21 Jul 2020
Pagine: 145 - 152

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Abstract

The aim of this study was to compare the effects of two resistance training programs including either a deadlift or a parallel squat on lower body maximal strength and power in resistance trained males. Twenty-five resistance trained men were randomly assigned to a deadlift group (DE; n = 14; age = 24.3 ± 4.1 y; body mass = 84.8 ± 14.2 kg; body height = 180.3 ± 6.8 cm) or to a squat group (SQ; n = 11; age = 22.3 ± 1.6 y; body mass = 83.0 ± 13.6 kg; body height 179.9 ± 6.1 cm). Both groups trained 3 times per week for 6 weeks. The deadlift and the squat were the only lower body maximal strength exercises performed by DE and SQ groups, respectively, while both training programs included jumps. A significantly (p = 0.017) greater increase in deadlift 1RM was observed in the DE compared to the SQ group, while the SQ group obtained a significantly (p = 0.049) greater increase in squat 1RM. A significant increase in jump performance (p = 0.010), without significant interactions between groups (p = 0.552), was observed in both groups. Three participants of the DE group developed lower back pain and were excluded from the study. Results indicate that both the squat and the deadlift can result in similar improvement in lower body maximal strength and jump performance and can be successfully included in strength training programs. The incidence of back pain in the DE group may suggest a marked stress of this exercise on the lower back. Proper technique should be used to minimize the risk of injury, especially when the deadlift is performed.

Key words

  • resistance training
  • jump performance
  • strength exercises
Accesso libero

Set-to-set Performance Variation in Tennis Grand Slams: Play with Consistency and Risks

Pubblicato online: 21 Jul 2020
Pagine: 153 - 163

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Abstract

The study analysed the set-to-set variation in performance using match statistics of 146 completed main-draw matches in Australian Open and US Open 2016-2017 men’s singles. Comparisons of technical-tactical and physical performance variables were done between different sets; and the within-match coefficients of variation (CV) of these variables were contrasted between match winning and losing players. All comparisons were realized via standardized (Cohen’s d) mean differences and uncertainty in the true differences was assessed using non-clinical magnitude-based inferences. Results showed that there was possibly to very likely decreases in the serve, net and running related variables (mean difference, ±90%CL: -0.16, ±0.14 to -0.45, ±0.24, small) and an increase in the return and winner related variables (0.17, ±0.24 to 0.24, ±0.14, small) in the last sets when compared to the initial sets, indicating the influence of match fatigue and the player’s choice of match tactics and pacing strategy. Besides, winning players were revealed to have lower CV values in most of performance variables (-0.16, ±0.24 to -0.82, ±0.23, small to moderate) except for the second serve, winner, and physical performance variables (0.25, ±0.26 to 1.6, ±0.25, small to large), indicating that they would sacrifice the consistency to gain more aggressiveness and to dominate the match.

Key words

  • performance profile
  • match statistics
  • analysis
  • winner
Accesso libero

How do Elite Soccer Teams Perform to Ball Recovery? Effects of Tactical Modelling and Contextual Variables on the Defensive Patterns of Play

Pubblicato online: 21 Jul 2020
Pagine: 165 - 179

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Abstract

Researchers in soccer match analysis have been using limited procedures to express the dynamics of the game and mainly focus on the attack. Therefore, the aims of this paper were to detect the successful teams’ ball recovery defensive patterns of play and study the influence of tactical modelling, halves, match status, opponent quality and stage competition on those patterns. The sample consisted of 1323 situations of defensive ball possession of the semi-finalist teams from the 2014 FIFA World Cup play-offs, which was collected by a valid and reliable observational instrument (Soccer-Defence). The Kruskal-Wallis H, Mann-Whitney U, Chi-square, Z-, multinomial logistic regression tests and sequential analysis (p < .05; z > 1.96) were used accordingly to test the differences and associations among and within teams of tactical modelling, tactical-technical behaviours and contextual variables to ball recovery. We found that among teams ball recovery differed in duration; H(3) = 14.958, p = .002. Germany were more likely to perform ball recovery by the goalkeeper than Argentina (p = .04; OR = 0.47) or the Netherlands (p < .05; OR = 0.50). Nevertheless, Brazil was the least likely to concede a shot off goal. Teams facing lower-ranked opponents were 0.63 times less likely to perform ball recovery by interception (p <.001). Additionally, sequential analysis illustrated that teams varied between central and lateral high-pressure zones before ball recovery in lower zones of the field. Finally, coaches could use such findings to design training exercises, create their own style of play, and set strategies.

Key words

  • match analysis
  • defensive phase
  • tactics
  • style of play
  • multinomial logistic regression
  • sequential analysis
Accesso libero

Effects of Resisted vs. Conventional Sprint Training on Physical Fitness in Young Elite Tennis Players

Pubblicato online: 21 Jul 2020
Pagine: 181 - 192

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Abstract

This study aimed to compare the effects of 6-week resisted sprint (RST) versus conventional (unresisted) sprint training (CG) on sprint time, change of direction (COD) speed, repeated sprint ability (RSA) and jump performance (countermovement jump (CMJ) and standing long jump (SLJ)) in male young tennis players. Twenty players (age: 16.5 ± 0.3 years; body mass: 72.2 ± 5.5 kg; body height: 180.6 ± 4.6 cm) were randomly assigned to one of the two groups: RST (n = 10) and CG (n = 10). The training program was similar for both groups consisting of acceleration and deceleration exercises at short distances (3-4 m), and speed and agility drills. The RST group used weighted vests or elastic cords during the exercises. After 6 weeks of intervention, both training regimes resulted in small-to-moderate improvements in acceleration and sprint ability (5, 10, 20 m), SLJ and CMJ performances, COD pivoting on both, the non-dominant (moderate effect) and the dominant (small effect) foot, and the percentage of decrement (small effects) during a RSA test. Between-group comparisons showed that the SLJ (Δ = 2.0%) and 5 m sprint time (Δ = 1.1%) improved more in the RST group compared with the CG group. This study showed that 6 weeks of RST or unresisted training are time-efficient training regimes for physical improvements in young male tennis players.

Key words

  • young athletes
  • sprint performance
  • tennis
  • power
Accesso libero

A Comparison of Incremental Running Field and Treadmill Tests in Young Soccer Players

Pubblicato online: 21 Jul 2020
Pagine: 193 - 201

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Abstract

The purpose of this study was to compare the incremental running tests performed by young soccer players on a treadmill (Tr) and in the field (FTcod: 100 m change of direction and FTcir: 100 m circle). Nineteen players (average age 17.4 ± 1.1 years; body height 172.0 ± 5.7 cm; body mass 68.9 ± 6.7 kg) volunteered to perform incremental Tr , FTcod and FTcir running tests. In all three tests, players ran for 3 min at 8, 10, 12 and 14 km∙h-1 and were given a 1 min rest interval between subsequent stages. Blood lactate concentrations (La-) were measured at 1 min rest intervals and the heart rate (HR) responses of players were recorded during the tests. After a 5 min recovery period, the second part of the test started; players ran at 15 km∙h-1 with velocity increments of 1 km∙h-1 every 1 min until exhaustion. This part was performed to determine maximum HR, maximum La- and the players’ final velocities. The results showed that players had significantly lower La- (F = 6.93, p = 0.07, η2 = 0.46, 95%CI(TR-FTcir) = -1.91/-0.34, 95%CI(TR-FTcod) = -1.59/-0.05) and HR (F = 9.08, p = 0.02, η2 = 0.53, 95%CI(TR-FTcir) = -6.98/-1.68, 95%CI(TR-FTcod) = -7.19/1.08) responses in the Tr test than in the FTcir and FTcod tests at 14 km∙h-1. It was also found that players completed the Tr test (F = 58.22, p = 0.00, η2 = 0.87) at higher final running velocities than the FTcir (95%CI(TR-FTcir) = 1.67/2.78) and FTcod (95%CI(TR-FTcod) = 1.69/2.85) tests. In conclusion, when coaches or sports scientists plan to train at higher running velocities or according to the final velocity in the test, it is advisable to carry out testing in the circumstances under which training will be carried out (in the field or on a treadmill).

Key words

  • heart rate
  • running velocity
  • blood lactate
  • running tests
Accesso libero

Differentiating African Teams from European Teams: Identifying the Key Performance Indicators in the FIFA World Cup 2018

Pubblicato online: 21 Jul 2020
Pagine: 203 - 208

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Abstract

Soccer is the most popular sport in the world. Despite this global popularity, European teams in contrast to African ones, have dominated the Fédération Internationale de Football Association (FIFA) World Cup tournaments for many decades. Therefore, the aim of this study was to examine the performance indicators that differentiated between African and European teams in the 2018 FIFA World Cup. Thirty matches played by five European (n = 15) and five African teams (n = 15) from the group stages of the World Cup were analysed using the InStat video system. The results showed that European teams had higher averages than African teams on the following performance variables: total shots, shots on target, goals scored from open play and set pieces, ball possession, short passes, medium passes, total passes, accurate passes and corner kicks. Therefore, soccer coaches should take note of these findings as they could serve as a benchmark for African teams to set trends and improve their performance at FIFA World Cup tournaments.

Key words

  • performance
  • tactics
  • set-play
  • open-play
  • goals
  • competition
Accesso libero

Evidence for the Relative Age Effect in the Spanish Professional Soccer League

Pubblicato online: 21 Jul 2020
Pagine: 209 - 218

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Abstract

The concept of the relative age effect refers to the consequences of the physical and psychological differences that may exist between those born earlier or later within the same calendar year. The objective of the present study was to examine this phenomenon in Spanish professional soccer, identifying the influences of the competitive level and the club of origin. The sample comprised 2,130 individuals from five competitive categories: under 12 (U12; n = 480), under 14 (U14; n = 338), under 16 (U16; n = 390), under 19 years old (U19; n = 489) and professional players (n = 433), with nine teams from the Spanish professional soccer league (PSL). Statistical analysis was based on a chi-squared test followed by calculation of the odds ratios and 95% confidence intervals. The main results show that at all levels of competition there was over-representation of individuals born in the first few months of the year. By clubs, the same over-representation was observed. It may be concluded that the relative age effect is consistent and exists throughout Spanish soccer, whether at youth or professional levels. An analysis by age categories showed a more pronounced effect in those competitions in which the youngest players participate, while in clubs the effect continued to be significantly present in all cases investigated in the study.

Key words

  • birth quarter
  • talent identification
  • potential
  • team sport games
Accesso libero

Effects of Training with an Agility Ladder on Sprint, Agility, and Dribbling Performance in Youth Soccer Players

Pubblicato online: 21 Jul 2020
Pagine: 219 - 228

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Abstract

The aim of this study was to examine the effects of coordination training using an agility ladder compared with a control group on physical fitness and technical performance in youth soccer players. Eighteen male youth soccer players (age: 12.2 ± 0.4 years; body height: 158.3 ± 10.8 cm; body mass: 45.0 ± 8.0 kg) were randomly assigned to an agility ladder group (n = 10) or a control group (n = 8). The intervention program was carried out three times a week over six weeks. Before and after the training period, the 10 m sprint, 20 m sprint, dribbling speed test, agility test, and slalom dribbling test performances were assessed. Within-group analysis showed significant improvements (p < 0.005) in 10 m and 20 m sprint performance from the pre- to the post-test for the agility ladder group (-2.39% and -2.10%) and the control group (-2.54% and -1.44%). No significant differences (p > 0.005) were found from the pre- to the post-test in the dribbling speed test, agility test, slalom dribbling test, and skill index. In the between-group analysis, there were no differences between the agility ladder group and the control group in any variable. In conclusion, the findings of this study suggest coordination training with an agility ladder does not seem to be effective to improve physical fitness and dribbling. Therefore, this information could be beneficial to players and coaches for programming tasks during soccer training sessions.

Key words

  • team sports
  • physical performance
  • physical training
Accesso libero

Prediction of Handball Players' Performance on the Basis of Kinanthropometric Variables, Conditioning Abilities, and Handball Skills

Pubblicato online: 21 Jul 2020
Pagine: 229 - 239

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Abstract

Handball (team handball) is a multifactorial sport. The aims of this study were (i) to analyse anthropometric variables, conditioning abilities, and handball skills in club handball players according to age and sex, and (ii) to develop multivariate models explaining club handball performance from a multidimensional perspective. Two hundred and twenty six handball players (age 16.9 ± 4.0 years, 54% males) participated in the study. The players belonged to under-14, under-16, under-19, and A teams. They were evaluated with a battery of 18 tests covering kinanthropometry, conditioning abilities, and handball skills. A one-way ANOVA with a Bonferroni post-hoc test was used to investigate differences between teams, and a t-test for differences between the sexes. For each team, a discriminant analysis was performed to determine differences between performance levels. The results showed little differences between the U19 and A teams in any of the variables studied in either men or women, and that the lowest values corresponded to the U14 team. The differences according to sex were clear in the kinanthropometric and conditioning variables, but much less so in handball skills. The eight multivariate models that were constructed classified successfully from 48.5 to 100% of the sample using at most three variables (except for the women's A team whose model selected six variables). Conditioning variables were most discriminating in men, and handball skills in women. This would seem to reflect the different performance profiles.

Key words

  • power
  • endurance
  • speed
  • velocity
  • team sports games
Accesso libero

Actual Playing Time of Water Polo Players in Relation to the Field Position

Pubblicato online: 21 Jul 2020
Pagine: 241 - 249

Astratto

Abstract

In water polo competitions, teams play four periods, each period consisting of eight minutes of actual playing time: a total of 32 minutes (Standard Actual Play Time, SAPT). Substitutions are permitted and a player may be substituted several times. The aim of this article was to provide reference data on played time, taking into consideration the field play position of the players. 352 male water polo players of 18 different nationalities were studied during two consecutive FINA World Championships. 180 games were analyzed and 1980 measurements of the game Measured Actual Play Time (MAPT) were taken. A time density index (DI) was calculated for each athlete using SAPT and MAPT. No statistically significant differences between the field positions were found with regard to age, as was the case in relation to teams between Game MAPT, Tournament MAPT and DI. However, when looking at the diverse field positions (field players, FP; center forward, CF; center back, CB), there were statistically significant differences: Game MAPT FPvsCB p = 0.03 and FPvsCF p = 0.03; Tournament MAPT FPvsCB p = 0.03; DI FPvsCB p = 0.03 and FPvsCF p = 0.04. In these competitions the water polo player had on average a MAPT value of 17.4 ± 6.1 min (54.6 ± 9.5% DI); there were athletes who played 2.3 min (7.1% DI) and others who played up to 31.6 min (95.3% DI). The MAPT in water polo is extremely variable among athletes and must be considered for a correct performance analysis. High-level water polo players require different training strategies depending on their MAPT.

Key words

  • match analysis
  • field position
  • age
  • periodization
  • training strategies

Section IV – Medical Issues of Sport and Eercise

Accesso libero

Does Oxygen Uptake Before Physical Exercise Affect Tear Osmolarity?

Pubblicato online: 21 Jul 2020
Pagine: 297 - 304

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Abstract

Recently, it has been reported that tear osmolarity (Tosm) is correlated with plasma osmolarity and will increase during exertion. We aimed to assess whether inhaling oxygen-enriched air between exercises could significantly change the Tosm value. Thirty men aged 24.9 years were included in the study. A cycloergometer was used to perform the exercise protocol. We recorded the participants’ Tosm (mOsm/L), heart rate (HR, beats/minute), oxygen saturation, and blood pressure values. After the first exhaustive exercise (T1), participants inhaled oxygen in the experimental group and a placebo in the control group. After the second exercise (T2), another set of measurements was obtained. The Tosm value before exercise was 297.4 ± 1.21 and 296.53 ± 1.11 mOsm/L (p = 0.61718) and the HR was 72.6 ± 2.59 and 73 ± 2.59 beats/minute (p = 0.39949) in the study and the control group, respectively. At T1, Tosm was 303.67 ± 1.25 and 302.2 ± 1.25 mOsm/L (p = 0.41286) and the HR reached 178.04 ± 2.60 and 176.4 ± 2.60 beats/minute (p = 0.65832), respectively. At T2, Tosm in the study group reached 305.73 ± 0.86 mOsm/L (correlation with the use of oxygen: r = −0.3818), and in the control group, it was 308.4 ± 0.86 mOsm/L (p = 0.0373), while the HR reached 172.20 ± 2.53 beats/minute in the study group and 178.2 ± 2.53 beats/minute in the control group (p = 0.057). It was concluded that inhaling oxygen before and after exercise could increase the rate of recovery after exhaustive exercise.

Key words

  • tearing
  • body water
  • sport
  • lacrimation
  • TearLab
  • Tosm
Accesso libero

Prevalence of Injuries in Exercise Programs Based on Crossfit®, Cross Training and High-Intensity Functional Training Methodologies: A Systematic Review

Pubblicato online: 21 Jul 2020
Pagine: 251 - 265

Astratto

Abstract

Current literature shows studies that question the safety of the practices carried out in high-intensity training modalities such as CrossFit®, Cross Training or High-Intensity Functional Training, which may lead to a greater risk in the prevalence of injuries. The aim of this study was to analyze in detail the prevalence of injuries occurring in training based on the CrossFit®, Cross Training or High-Intensity Functional Training modalities, through a systematic review, as well as evaluating the methodological quality of the included studies. We used the recommendations of the PRISMA protocol. For the quality analysis of the studies, we applied the tool proposed by the National Institute of Health (United States). The areas that mainly present a higher risk of injury during CrossFit, Cross Training or High-Intensity Functional Training practices are shoulders, knees and back. Additionally, 11 of the 12 included studies displayed a poor methodological quality according to the quality tool used.

Key words

  • training
  • high-intensity
  • sports injuries
  • gym
  • cross training
Accesso libero

Mini-Basketball Training Program Improves Physical Fitness and Social Communication in Preschool Children with Autism Spectrum Disorders

Pubblicato online: 21 Jul 2020
Pagine: 267 - 278

Astratto

Abstract

This investigation examined the effects of a 12-week mini-basketball training program (MBTP) on physical fitness and social communication in preschool children with autism spectrum disorders (ASD). The study applied a quasi-experimental design. Fifty-nine preschool children aged 3-6 years with ASD were assigned to either a MBTP group (n = 30) or a control group (n = 29). Participants in the MBTP group received a scheduled mini-basketball training program (5 sessions per week, forty minutes per session) for twelve consecutive weeks, while the control group was instructed to maintain their daily activities. The physical fitness test and the parent-reported Social Responsiveness Scale Second Edition (SRS-2) test were performed before and after the intervention. Results indicated that the 12-week MBTP facilitated performance in the physical fitness test, particularly in speed-agility and muscular strength abilities. Additionally, children in the MBTP group demonstrated improvement in SRS-2 performance in social awareness, social cognition, social communication, and autistic mannerisms, whereas no such changes were found in the control group. It may be concluded that the 12-week MBTP could improve physical fitness and social communication in preschool children with ASD, and thus the use of physical exercise intervention as a therapeutic tool for preschoolers with ASD is recommended.

Key words

  • mini-basketball
  • physical fitness
  • social communication
  • preschool children
  • autism spectrum disorders
  • quasi-experimental

Section IV – Behavioural Sciences in Sport

Accesso libero

Prevalence of Urinary Incontinence in High-Impact Sport Athletes: A Systematic Review and Meta-Analysis

Pubblicato online: 21 Jul 2020
Pagine: 279 - 288

Astratto

Abstract

The aim of this study was to systematize the scientific evidence that assessed the prevalence of urinary incontinence in female athletes and determine which modality is most predisposed to stress urinary incontinence. From September to December 2018, a systematic literature search of current interventional studies of stress urinary incontinence of the last ten years was performed using PubMed, EMBASE, Scopus and Web of Science databases. The methodological quality was assessed by the Downs and Black scale, while the data collected from the studies were analyzed through meta-analysis. Nine studies met the eligibility criteria, meaning they included reports of urinary incontinence in different sports. The meta-analysis showed 25.9% prevalence of urinary incontinence in female athletes in different sports, as well as 20.7% prevalence of stress urinary incontinence. The most prevalent high impact sport was volleyball, with the value of 75.6%. The prevalence of urinary incontinence can be high in female athletes, with high-impact sports potentially increasing the risk for stress urinary incontinence. Further research is needed regarding the potential risk factors related to the onset of urinary incontinence.

Key words

  • exercise
  • female athletes
  • pelvic floor muscle
  • stress urinary incontinence
Accesso libero

Effects of High-Velocity Strength Training on Movement Velocity and Strength Endurance in Experienced Powerlifters with Cerebral Palsy

Pubblicato online: 21 Jul 2020
Pagine: 235 - 243

Astratto

Abstract

The present study aimed to evaluate the effects of a 6-week high-velocity strength training (HVST) intervention on movement velocity and strength endurance in experienced powerlifters with cerebral palsy (CP). Eleven experienced powerlifters with CP and seven from a control group (CON), were subjected to 6-week HVST. An assessment of movement velocity and strength endurance was conducted one week before (T1) and one week after (T2) the 6-week training intervention. During testing, athletes performed a maximum number of bench press repetitions possible within 5 sets of 15 s each, with 1-min passive rest intervals in-between. The indicator of movement velocity was the weight pressed in the first 5 s (5sW) in all performed sets. Strength endurance was described by the total weight (TW) pressed during the test. 5sW in T2 was significantly higher as compared with T1 in the CP group only (T1 928.9 ± 342.9 kg vs. T2 1007.3 ± 324.6 kg; p = 0.016). TW in T2 was significantly higher as compared with T1, both in the CP group (T1 2550.5 ± 843.9 kg vs. T2 2809.8 ± 981.3 kg; p < 0.001) and in the CON group (T1 2300.7 ± 845.1 kg vs. T2 2468.9 ± 890.1 kg; p = 0.049). A 6-week program of HVST increased movement velocity in resistance trained CP athletes. The gains of strength endurance were observed in both groups.

Key words

  • performance
  • disabled athletes
  • resistance exercise
  • resistance

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