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Aquatic Sports and Activities

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Presentation of the 1st International Symposium on Strength & Conditioning (ISSC 2011)

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Journal Details
Format
Journal
eISSN
1899-7562
First Published
13 Jan 2009
Publication timeframe
5 times per year
Languages
English

Search

Volume 83 (2022): Issue 1 (August 2022)

Journal Details
Format
Journal
eISSN
1899-7562
First Published
13 Jan 2009
Publication timeframe
5 times per year
Languages
English

Search

28 Articles

Section I - Kinesiology

Open Access

Kinematic Factors Associated with Hitting Hurdles during the Initial Phase of a 110-m Hurdle Race

Published Online: 08 Sep 2022
Page range: 5 - 12

Abstract

Abstract

This study aimed to clarify the kinematic factors for the cause and effect of hitting hurdles during the initial phase of a 110-m hurdle run. Nine experienced male hurdlers participated in this study (body height: 1.74 ± 0.04 m, body mass: 67.4 ± 5.9 kg, age: 20.2 ± 1.4 years, personal best: 15.21 ± 0.47 s, seasonal best: 15.33 ± 0.55 s). Hurdlers undertook 12 trials of the initial phase of hurdling from the start to the second hurdle landing. Dual-sided sagittal plane motion was obtained from images from two high-speed cameras operating at 120 Hz. One ‘hit’ trial which had the largest horizontal displacement of markers fixed on the hurdle and one ‘non-hit’ trial which had the fastest time of hurdle clearance were extracted for each participant. Kinematic variables were compared between the two trials. Significantly lower height of the whole-body centre of mass at the take-off was found as a possible cause of hitting hurdles, caused by insufficient swing-up of the lead leg thigh. In contrast to conventional understanding, take-off velocity, take-off distance and the take-off angle were comparable between the ‘hit’ trial and ‘non-hit’ trial. Regarding the effect of hitting hurdles, it was observed that running velocity during hurdling was not substantially reduced. However, several characteristic movements were identified that might induce inefficient motion to re-accelerate running velocity during the following landing steps.

Key words

  • motion analysis
  • athletics
  • kinematics
Open Access

The Effect of Arm Dominance on Knee Joint Biomechanics during Basketball Block Shot Single-Leg Landing

Published Online: 08 Sep 2022
Page range: 13 - 21

Abstract

Abstract

Single arm blocking is a key component of successful basketball defence. The player uses either their dominant or non-dominant arm to block the ball landing on a common leg. Understanding how the bio-physical loads of the landing leg change as a function of the blocking arm will provide insights into potential injury risk of the lower limb. The aim of this study was to investigate the effects of arm dominance on the biomechanical variables of injury risk of the lower limb, specifically the knee joint during the single-leg landing in female basketball players. Kinematic and kinetic data were collected from fourteen female basketball athletes (20.85 ± 1.35 years, 1.69 ± 0.06 m, 60.37 ± 7.75 kg), each performing three trials of a dominant arm and non-dominant block jump landing on the dominant leg. The results showed significantly higher anterior and medial ground reaction force, knee joint flexion and abduction and lateral knee force during the dominant arm landing (p < 0.05). These findings highlight potential injury risk and the need for the player to be more proficient at dominant arm block-shot landing. The player should aim to develop a larger landscape of technique to meet the demands of the game and facilitate a more effective and safer landing strategy.

Key words

  • anterior cruciate ligament injury
  • arm movement
  • basketball
  • knee joint biomechanics
Open Access

Biomechanical Adjustments of the Basketball Jump Shot Performed over Differently High Opponents

Published Online: 08 Sep 2022
Page range: 23 - 28

Abstract

Abstract

Biomechanical adjustments of the jump shot in presence of an opponent and their associations with shooting efficiency remain to be determined in elite basketball. The aim of this research was to examine the selected biomechanical determinants of the jump shot when shooting over opponents of different height. Nineteen elite basketball players, age 22 ± 3 years, performed three trials of 20 basketball shots in a crossover, randomised manner: over an obstacle of the height of standing reach (RH), over reach height with additional 20 cm (RH+20 cm), over reach height with additional 40 cm (RH+40 cm), and the maximum height jump shot without an obstacle (JSmax). Jump height, the ball entry angle, and shooting efficiency were measured on each trial. Jump height when shooting over RH+40 cm was significantly higher than RH+20 cm (+0.022 m, p = 0.030) and RH (+0.023 m, p = 0.029). Similarly, the ball entry angle was greater at RH+40 cm compared to RH (+7.19 °, p < 0.001) and RH+20 cm (+2.90°, p < 0.001). In contrast, shooting efficiency decreased significantly when shooting over RH+40 cm compared to RH (-10.79%, p = 0.048) and RH+20 cm (-8.95%, p = 0.015). We recorded the highest jump height (0.35 ± 0.08m, p < 0.001) and the lowest angle of entry (39.16 ± 1.19°, p < 0.001) when participants performed JSmax. Shooting over higher opponents should be prioritised in training to significantly improve shooting efficiency. Future research is needed to determine additional potential biomechanical determinants of a successful jump shot in elite basketball.

Key words

  • kinematics
  • jump shot
  • shooting angle
  • efficiency
  • basketball performance
Open Access

Effects of Leg Stiffness Regulated by Different Landing Styles on Vertical Drop Jump Performance

Published Online: 08 Sep 2022
Page range: 29 - 37

Abstract

Abstract

The purpose of this study was to investigate the effects of stiffness regulated by landing styles on drop jump performance. Twenty-four male lacrosse athletes performed drop jumps with stiff (ST), self-selected (SS), and soft (SF) landing from a 0.42 m box. Leg stiffness, ground contact time, depth, jump height, maximum ground reaction force (GRF), GRF at the start of the propulsive phase, mean power, peak power, and the reactive strength index (RSI) were calculated. The results showed that jump height and the RSI had strong correlations to power production in all drop jump styles. Power would be a key factor to overall athletic performance. Repeated measures ANOVA showed significant differences (p < 0.05) in all variables among the three styles. Drop jumps with SS landing had comparable jump height to drop jumps with SF landing and power output to drop jumps with ST landing. Drop jumps with ST landing had significantly lower jump height, but higher GRF, power, and the RSI compared to drop jumps with SF landing. In drop jump testing, drop jumps with SS landing should be used if power and jump height were the major concerns; if the RSI was the major concern, drop jumps with ST landing should be used. Training with drop jumps, one of the main objectives should be increasing power output due to its significant correlation to jump height and the RSI in all conditions.

Key words

  • stretch-shortening cycle
  • stiff
  • soft
  • power
  • reactive strength
Open Access

Contributing Factors to Sensorimotor Adaptability in Reactive Agility Performance in Youth Athletes

Published Online: 08 Sep 2022
Page range: 39 - 48

Abstract

Abstract

Sensorimotor adaptability facilitates adjusting behaviour for changing environmental stimuli to maintain appropriate goal-directed motor performance. Its effectiveness is associated with perceptual-cognitive modulation. As the factors affecting it are still not completely known, the aim of our study was therefore to analyse the association between selected variables (demographic, training, anthropometric, genetic) and sensorimotor adaptation in reactive agility tasks in youth team-sport athletes. The study group consisted of 85 youth athletes (aged 12.61 ± 0.98 years). Based on an initial evaluation, participants were divided into faster and slower agility groups. The resultant differences between change of direction speed tests and reactive agility tests provided the REAC-INDEX as a dependent variable. The independent variables were as follows: gender, calendar age, body mass, height, BMI, maturity offset, training status and the BDNF rs6265 polymorphism. Multiple linear regression showed that the maturity offset (ß = 0.269; p = 0.012) and calendar age (ß = -0.411; p < 0.001) significantly contributed to the REAC-INDEX of all participants (R2 = 0.13). In the slower group, the c.196G BDNF allele had a significant influence (ß = -0.140; p = 0.044) on the REAC-INDEX. The best predictive model comprised female gender (ß = 0.799; p < 0.001), maturity offset (ß = -0.586; p < 0.001) and training experience (ß = -0.225; p = 0.009), contributing to 49% of RA variance. Sensorimotor adaptability is mainly dependent on gender and age, and can be improved through systematic sports training. The BDNF rs6265 polymorphism may be considered a contributing factor to SA variability in the initial stages of training, although polymorphism-related differences blurred as the effect of participation in sports training increased.

Key words

  • gender
  • maturity
  • age
  • brain-derived neurotrophic factor
  • team sport games

Section II - Exercise Physiology & Sports Medicine

Open Access

Does the Self‐Myofascial Release Affect the Activity of Selected Lower Limb Muscles of Soccer Players?

Published Online: 08 Sep 2022
Page range: 49 - 57

Abstract

Abstract

Myofascial therapy has already become one of the basic forms of treatment of the locomotor system. One form of the therapy is Self-Myofascial Release, in which external force is applied to the body with the help of special rollers (foam rolling, FR). The aim of the study was to investigate the direct effect of Self-Myofascial Release of hamstring muscles using a foam roller on the bioelectric activity of selected muscles (biceps femoris and gluteus maximus) during squats. The study involved 40 male soccer players, who were randomly divided into two groups: experimental and control. The tests used did not show significant differences in the analyzed variables before the experiment (baseline measurement p > 0.05), while significant intergroup differences appeared for subsequent measurements, both for reference MVC values (p < 0.01 - for % gluteus maximus MVC, p < 0.001 - for % biceps femoris MVC) and for raw EMG values (p < 0.01 gluteus maximus and p < 0.001 - for % 0.0001 for biceps femoris). The use of self-myofascial release within the hamstring muscles leads to changes in the electrical potential of the muscles of the lower limb.

Key words

  • electromyography
  • foam rolling
  • hamstring
  • soccer
  • myofascial self-release
Open Access

Evaluation of Water Intake in Spanish Adolescent Soccer Players during a Competition

Published Online: 08 Sep 2022
Page range: 59 - 66

Abstract

Abstract

An optimal state of hydration is essential to maintaining health. The objective of this cross-sectional study was to evaluate the water intake of adolescents aged 12 to 16 years and their hydration level during an official soccer match. Three hundred and six players participated in the study (N = 306). Their water intake was recorded and the level of hydration was evaluated using the density of urine as an indicator. Weight measurements were made before and after the match. Water intake control, urine collection and analysis, and the recording of minutes played were carried out after the match. The average weight loss was 746.2 g (SD: 474.07; p < 0.001), with 36.5% with less than 1% loss and 23.3% with more than 2% loss. The mean volume of water ingested was 229.35 ml (SD: 211.11) and a significant correlation was observed between minutes of activity (ρ-value = 0.206; p < 0.001), environmental humidity (ρ-value = - 0.281; p < 0.001), and temperature (ρ-value = 0.200; p < 0.001). The sweat rate was 0.69 l/h (SD: 0.56) and it was significantly associated with playing time (ρ-value = -0.276; p < 0.001). The mean urine density was 1.019 (SD: 0.007), with 64.9% of youth athletes showing dehydration (≥ 1.020). An association was observed between dehydration and activity time (U- value = 4.124; p < 0.001). Approximately 10% of the participants stated that they had not drunk any water during the match. In conclusion, it is necessary to establish individual hydration guidelines based on personal, environmental and activity-related factors, as well as establish a minimum volume of fluids to consume.

Key words

  • soccer
  • adolescent
  • hydration status
  • water intake
Open Access

Myofascial and Movement Tests after Anterior Cruciate Ligament Reconstruction

Published Online: 08 Sep 2022
Page range: 67 - 75

Abstract

Abstract

Functional evaluation after anterior cruciate ligament reconstruction is one of the key points involved in decision making about the return of patients to full and unrestricted physical activity. The objective of the present study was to verify whether myofascial chain NEURAC® and Functional Movement Screen (FMS™) tests can be used to detect functional differences between the operated and the non-operated extremity in patients after anterior cruciate ligament reconstruction. A total of 83 young and physically active recreational athletes (mean age: 26.9 ± 9.7 years) who underwent primary single-bundle anterior cruciate ligament reconstruction using an autogenous semitendinosus-gracilis tendon graft were evaluated between the 3rd and the 4th month after surgery. Subjects received a similar, standardised rehabilitation programme. Two experienced raters, blinded to the objective of this study, were involved in functional outcome data collection using myofascial NEURAC® and Functional Movement Screen tests. Only two of the NEURAC® tests showed significant differences in the results between the operated and the non-operated extremity: the supine bridging (mean 2.92 vs. 3.51 points, p < 0.001) and prone bridging (mean 2.76 vs. 3.67 points, p < 0.001) tests. Additionally, the summary score of all NEURAC® tests significantly differed between extremities (mean 12.08 for the operated vs. 13.67 points for the non-operated extremity, p < 0.001). Myofascial tests (supine and prone bridging) in comparison with a battery of Functional Movement Screen tests seem to be more effective in detecting functional differences between the operated and the non-operated extremity at the early stage of recovery after anterior cruciate ligament reconstruction.

Key words

  • functional performance
  • NEURAC® myofascial tests
  • Functional Movement Screen™ tests
  • return to sport criteria
Open Access

Validity and Reliability of New Equations for the Prediction of Maximal Oxygen Uptake in Male and Female Elite Adolescent Rowers

Published Online: 08 Sep 2022
Page range: 77 - 86

Abstract

Abstract

The aim of this study was to develop accurate, reliable, and reproductive equations for the prediction of maximum oxygen uptake ( V ˙ $\dot{V}$O2max) in male and female high-level adolescent rowers. This study included two parts. In the first part, V̇O2max was evaluated in 106 male and 83 female high-level adolescent rowers during an incremental step test (IRT) on a rowing ergometer, and stepwise multiple regression analyses were used for the development of new equations. In the second part, these equations were tested in 26 new high-level adolescent rowers of the same age and anthropometrical characteristics (boys: 15.27 ± 2.70 yrs and 15.34 ± 2.80 yrs; 72.37 ± 10.96 kg and 70.96 ± 10.65 kg; girls: 15.00 ± 2.11 yrs and 15.94 ± 2.71 yrs; 62.50 ± 7.14 kg and 63.41 ± 6.72 kg for parts 1 and 2, respectively; p > 0.05). V̇O2max was predicted from the combination of lean body mass (LBM) and the distance covered during the last 4 min stage of the IRT (boys: r2 = 0.715, F = 68.74, p = 0.001; girls: r2 = 0.769, F = 57.81, p = 0.001). In the second part, no significant differences were identified when the new equations were tested against measured V̇O2max (boys: 3971.15 ± 713.38 mL·min−1 vs. 3915.83 ± 704.43 mL·min−1; girls: 3272.75 ± 551.46 mL·min−1 vs. 3308.94 ± 557.59 mL·min−1 for measured and predicted values, respectively; p > 0.05). In conclusion, V̇O2max of high-level adolescent rowers can be predicted with high accuracy, reliability, and repeatability using simple and easily evaluated anthropometric and performance variables.

Key words

  • rowing performance
  • youth athletes
  • children
  • rowing test
  • maximal oxygen uptake
Open Access

Muscle Oxygen Saturation Breakpoints Reflect Ventilatory Thresholds in Both Cycling and Running

Published Online: 08 Sep 2022
Page range: 87 - 97

Abstract

Abstract

Pulmonary gas exchange analysis was compared to changes in muscle oxygen saturation as measured by near-infrared spectroscopy. First, ventilatory thresholds determined by common gas exchange analysis and breakpoints in muscle oxygen saturation were assessed for agreement during exercise with increasing intensity. Secondly, the relationship between muscle oxygen saturation as a surrogate for local oxygen extraction and peak oxygen uptake was assessed. In order to lend robustness to future NIRS testing on a broader scale, considering its potential for simple and cost-effective application, the question of a running versus a cycling modality was integrated into the design. Ten participants, of whom five were recreationally trained cyclists and five recreationally trained runners, were tested; each during a cycling test and a running test with increasing intensity to voluntary exhaustion. Muscle oxygen saturation and pulmonary gas exchange measurements were conducted. Bland-Altman analysis showed a moderate degree of agreement between both muscle oxygen saturation breakpoint 1 and muscle oxygen saturation breakpoint 2 and corresponding ventilatory threshold 1 and ventilatory threshold 2, for both cycling and running disciplines; generally speaking, muscle oxygen saturation breakpoints underestimated ventilatory thresholds. Additionally, a strong relationship could be seen between peak oxygen uptake and the minimally attained muscle oxygen saturation during cycling exercise. Muscle oxygen saturation measured using NIRS was determined to be a suitable method to assess ventilatory thresholds by finding breakpoints in muscle oxygen saturation, and muscle oxygen saturation minimum was linked to peak oxygen uptake.

Key words

  • NIRS
  • anaerobic threshold
  • tissue oxygen saturation
  • lactate threshold
Open Access

Effect of Beta-Alanine Supplementation on Exercise-Induced Cell Damage and Lactate Accumulation in Female Basketball Players: a Randomized, Double-Blind Study

Published Online: 08 Sep 2022
Page range: 99 - 107

Abstract

Abstract

Beta-alanine (BA) is a supplement that has received attention for its buffering potential among athletes. The aim of this study was to investigate the effects of BA supplementation on exercise performance and exercise-induced cell damage in female basketball players. Twenty-two female basketball players participated in a randomized, double-blind study. They ingested 6.4 g·day-1 of BA or an isocaloric placebo (dextrose) over 4 weeks. Exercise performance including aerobic (Bruce test), anaerobic (Wingate test), intermittent (Yo-Yo test) and basketball performance (countermovement jump and free throw shots) was measured before and following the intervention. Exercise measures were performed at the lab and free throw shots were undertaken on a wooden indoor basketball court. Blood samples were also collected before and after the exhaustive exercise to assess lactate concentration, creatine kinase (CK), lactate dehydrogenase (LDH) and malondialdehyde (MDA) activity. The exhaustive exercise test induced an increase in lactate concentration and MDA, CK and LDH activity (all p < 0.05). BA supplementation significantly reduced the lactate response to exhaustive exercise (p = 0.001); however, it had no significant effect on exercise-induced MDA, CK and LDH activity (all p > 0.05). Furthermore, exercise performance measures improved from pre- to post-test regardless of supplement/placebo ingestion (all p < 0.05). BA consumption over 4 weeks significantly reduced lactate accumulation following exhaustive exercise, but had no ergogenic effect in female basketball players. Usual dosing of BA does not seem to exhibit protective effect against oxidative damage.

Key words

  • buffering capacity
  • carnosine
  • oxidative damage
  • muscle damage
Open Access

Carbohydrate Rinse Fails to Enhance Cycling Performance or Alter Metabolic and Autonomic Recovery in Recreational Cyclists

Published Online: 08 Sep 2022
Page range: 109 - 119

Abstract

Abstract

The purpose of the study was to examine the effects of carbohydrate (CHO) mouth rinsing on autonomic and metabolic recovery as well as cycling performance. Ten male recreational cyclists (age = 30 ± 6 years, VO2peak = 54.5 ± 8.1 mL·kg-1·min-1) completed a randomized, double-blind, placebo-controlled, crossover designed study. A CHO or a placebo (PLA) rinse was administered every 12.5% of a work to completion trial (75%Wmax). Heart rate variability (lnRMSSD), the respiratory exchange ratio, and plasma epinephrine, norepinephrine, insulin, glucose, free fatty acids (FFA), and lactate were measured pre- and post-exercise. The CHO rinse did not improve time to completion of the test trial (CHO: 4108 ± 307 s, PLA: 4176 ± 374 s, p = 0.545). Further, the CHO rinse did not impact autonomic recovery, as measured by lnRMSSD (p = 0.787) and epinephrine (p = 0.132). Metabolic biomarkers were also unaffected by the CHO rinse, with no differences observed in responses of FFA (p = 0.064), lactate (p = 0.302), glucose (p = 0.113) or insulin (p = 0.408). Therefore, the CHO mouth rinse does not reduce the acute sympathetic response following strenuous exercise and does not result in improvements in cycling time to completion.

Key words

  • carbohydrate solution
  • endurance performance
  • cycling
  • heart rate variability
  • autonomic nervous system
  • exercise metabolism
Open Access

Submaximal Testing to Estimate Aerobic Capacity Using a Matrix C5x Stepmill

Published Online: 08 Sep 2022
Page range: 121 - 129

Abstract

Abstract

The primary purpose of this study was to determine if the Matrix C5x stepmill’s preprogrammed submaximal test is able to accurately predict maximal oxygen uptake. Sixteen participants completed a maximal treadmill test and a preprogrammed submaximal test on a Matrix C5x stepmill. Oxygen uptake was measured using a Cosmed K5 during both tests. Maximal oxygen uptake (VO2max) was calculated from submaximal data using a multi-stage calculation and compared against measured VO2max from the maximal test and estimated VO2max from the submaximal stepmill test. METs were also measured during the submaximal test and compared to the METs estimated by the stepmill and METs calculated using submaximal stepping equations. Measured VO2max (39.18 α 6.6 ml.kg-1.min-1) was significantly higher (p < 0.001) than estimated VO2max (28.06 α 3.2 ml.kg-1.min-1) and calculated VO2max (35.58 α 8.0 ml.kg-1.min-1). Measured METs were significantly (p = 0.04) higher than estimated METs in all stages, and higher than calculated METs in stage 1 of the submaximal test. The C5x did not provide accurate estimations of METs or maximal oxygen uptake. Calculating maximal oxygen uptake from submaximal stepmill data may provide an alternative, although development of a new equation may be warranted.

Key words

  • VO
  • METs
  • Watts
  • stair climbing
  • stepmill
Open Access

Effect of High‐Intensity, Intermittent, Short‐Duration Re‐Warming Up on Cycling Sprint Performance

Published Online: 08 Sep 2022
Page range: 131 - 141

Abstract

Abstract

The aim of this study was to investigate the effects of warming up again during half-time (i.e., re-warm up [RW]) with high-intensity, intermittent, short-duration exercise on cycling sprint performance. Participants (male, n = 10) performed intermittent cycling exercise for 40 min, followed by a 15-min half-time period with either rest only (control trials [CON]) or rest followed by a RW (three intervals of 3 s of maximal-effort cycling and 27 s of rest [HII]), after which participants performed the Cycling Intermittent-Sprint Protocol (CISP) to evaluate their sprint performance (17.0 ± 1.4°C, 44.2 ± 7.0% relative humidity). CISP intervals comprised 10 s rest, 5 s maximal effort cycling, and 105 s active recovery at 50% of the maximum oxygen uptake (VO2max) and were repeated 10 times. All participants performed both trial variations in randomized order. Peak power output of 5-s cycling sprints during the CISP were significantly higher in HII trials than those in CON trials (CON: 813 ± 109 W, HII: 836 ± 118 W, p < 0.05). Oxygen uptake, blood lactate concentration, and the rating of perceived exertion at the beginning of the second half after the RW were significantly higher in HII trials than those in CON trials (p < 0.05). These results demonstrate that the RW with intermittent, high-intensity, short-duration exercise improved subsequent cycling sprint performance in a thermoneutral environment and may represent a new useful RW strategy.

Key words

  • sports
  • sprinting
  • half-time
  • intermittent exercise
  • heart rate
  • blood lactate concentration
Open Access

Associations between Selected Biological Features and Absolute and Relative Swimming Performance of Prepubescent Boys over a 3‐Year Swimming Training Program: A Longitudinal Study

Published Online: 08 Sep 2022
Page range: 143 - 153

Abstract

Abstract

The study aimed to investigate the effect of 3-year swimming training on selected biological variables in prepubescent male swimmers and to determine the best predictors of absolute (VSa) and relative (VSr) swimming velocity for 50 m and 400 m front crawl. Twenty-one 10-year old boys subjected to endurance swimming training (4 x 70 min per week) and 18 boys consisting a control group were assessed semi-annually for basic anthropometric and respiratory characteristics, breath-hold time (BHT), VO2max, leg explosiveness (HJ), and abdominal strength endurance (ASE). After three years of training, BHT (p < 0.001), VO2max (p < 0.01), HJ (p < 0.01) and ASE (p < 0.01) were greater in the swimmers than in the controls. VSa and VSr expressed as a percentage of baseline velocity increased more for the 50 m than for the 400 m distance (p < 0.001 and p < 0.01, respectively). The 50 m VSa and VSr positively correlated with those obtained for the distance of 400 m (in both cases p < 0.001). Baseline VSa was negatively correlated with the increase in absolute swimming velocity for both distances (50 m: r = -0.684, p < 0.001 and 400 m: r = -0.673, p < 0.001). The best predictors of VSa for 50 m and 400 m front crawl were HJ (r2 = 0.388; p < 0.001) and VO2max (r2 = 0.333; p < 0.001), respectively. The key predictors of VSr for both distances were age (50 m: r2 = 0.340, p < 0.001 and 400 m: r2 = 0.207, p < 0.001) and, after excluding it from analysis, HJ (50 m: r2 = 0.176, p < 0.001 and 400 m: r2 = 0.104, p < 0.001). These results suggest that regardless of prepubescent boys’ initial abilities and exercise capacity, improvement in their swimming performance mainly depends on increases in power and neuromuscular coordination.

Key words

  • swimming performance
  • relative swimming velocity
  • physical capacity
  • prepubescent boys
  • longitudinal study
Open Access

Elite Rugby Players Have Unique Morphological Characteristics of the Hamstrings and Quadriceps Femoris Muscles According to their Playing Positions

Published Online: 08 Sep 2022
Page range: 155 - 163

Abstract

Abstract

Rugby is a popular sport requiring high-intensity and maximal speed actions. Numerous studies have demonstrated that physical performance variables, such as strength, sprinting, and jumping, are different between the forwards and backs. However, there is little information about muscle morphological characteristics specific for each rugby playing position. This study aimed to clarify the morphological characteristics of the thigh muscles in forwards and backs. Ultrasound images were obtained from the proximal, middle, and distal regions of the thigh. Then, the anatomical cross-sectional areas of particular muscles in the hamstrings and quadriceps femoris were calculated for seven forwards, seven backs, and ten non-athletes. The anatomical cross-sectional areas were normalised by the two-third power of lean body mass, and the normalised values of the three regions were averaged as that of the individual muscle. In the hamstrings, the normalised anatomical cross-sectional areas of the biceps femoris long head were significantly greater in forwards than in non-athletes, whereas those of the semitendinosus were significantly greater in backs than in non-athletes. Furthermore, in the quadriceps femoris, the normalised anatomical cross-sectional areas of the rectus femoris and vastus intermedius were significantly greater in forwards than in backs and non-athletes. These results suggest that forwards have great muscularity of the biceps femoris long head and vastus intermedius which can generate large force, whereas backs possess great muscularity of the semitendinosus which can generate high contraction velocity. These findings allow coaches to design more effective training programs according to particular rugby playing positions.

Key words

  • muscle size
  • forward
  • backs
  • ultrasonography

Section III – Sports Training

Open Access

External and Internal Training Loads for Intensive and Extensive Tactical-Conditioning in Soccer Small Sided Games

Published Online: 08 Sep 2022
Page range: 165 - 173

Abstract

Abstract

This study aimed to investigate the external (ETLs; 15-Hz GPS unit coupled with a 100 Hz tri-axial accelerometer) and internal training loads (ITLs; session-RPE method) of 18 elite U20 soccer players (19 ± 1.0 years, 178 ± 8 cm, 71 ± 7 kg) undertaking a tactical-conditioning training program with special reference to small-sided games (SSGs). The SSGs used in this program were either extensive (SSG-extensive) or intensive (SSG-intensive) training sessions, that were alternated within the assessed weeks. Tactical principles of the game influenced the aim of the technical-tactical content. Total distance (TDR; ES: 1.17), and a very high-speed running distance (HSR; ES: 0.96) were greater in SSG-extensive vs. SSG-intensive. However, no meaningful difference was found for accelerations (ACC; ES: 0.12) and decelerations (DEC; ES: 0.08). However, a higher perceived intensity (session-RPE; ES: 0.62) and greater ITLs (ES: 0.27) were found for SSG-intensive. These findings suggest that coaches should prescribe SSG training sessions not only considering the usual variables (rules, player numbers, etc.). The current data indicate that the tactical objective of SSGs in relation to exercise bout duration and rest intervals should be considered, while implementing a multi-dimensional training monitoring program during SSG tactical-conditioning training sessions, integrating ETL and ITL variables to gain a better understanding of training responses.

Key words

  • internal load
  • external load
  • game-based training
  • elite athletes
Open Access

External Workload Compared Between Competitive and Non-Competitive Matches for Professional Male Soccer Players

Published Online: 08 Sep 2022
Page range: 175 - 184

Abstract

Abstract

The purpose of this study was to compare the external load in competitive (official) and non-competitive matches (friendly, training and modified-sided games) in professional soccer players. Time-motion data for 10 elite male soccer players (age = 20.1 ± 2.1 years; body height = 178.8 ± 5.9; body mass = 71.4 ± 7.3; % body fat = 11.0 ± 1.1 and VO2max = 55.96 ± 3.3) from a professional Spanish first division team were recorded during official (n = 12), friendly (n = 7) and training (n = 6) matches and a 5 vs. 5 + goalkeepers modified-sided game (n = 3). GPS devices were used to monitor players’ external loads: total distance covered, distance covered at different speeds (<13.9 km·h-1, >14, >18, >21 and >25 km·h-1), peak speed (km·h-1), and the number of accelerations and decelerations (1.5–2.5 m·s-2, 2.5–4 m·s-2 and 4–8 m·s-2). One-way analysis of variance of the magnitude-based inference was used to determine differences between matches. Data indicated that official matches scored statistically higher peak speeds (ES = 1.40–2.20). In modified-sided games more total distance was covered at <13.9 km·h-1 and >14 km·h-1 than in regular matches (ES = 0.72–2.21), but lower distances were covered at >21 km·h-1 and >25 km·h-1 than in official and friendly matches (ES = 0.51–2.53) and at >25 km·h-1 than in training matches (ES = 0.92). Likewise, the modified-side games showed a greater number of accelerations and decelerations than other types of matches (ES = 1.46–2.51). This work shows that friendly and training matches, in conjunction with modified-side games, are suitable tools to prepare soccer players for official matches.

Key words

  • soccer
  • training
  • small-sided games
  • GPS
  • time-motion analyses
Open Access

Validity and Reliability of Strategy Metrics to Assess Countermovement Jump Performance Using the Newly Developed My Jump Lab Smartphone Application

Published Online: 08 Sep 2022
Page range: 185 - 195

Abstract

Abstract

The aim of the present study was to analyse the validity and reliability of the newly developed My Jump Lab smartphone app, which includes the option to calculate time to take-off and the reactive strength index modified (RSI_Mod – calculated as jump height divided by time to take-off), in addition to jump height. Twenty-seven postgraduate sport science students attended a single test session and performed three maximal effort countermovement jumps (CMJ) on twin force plates, whilst concurrently being filmed using the app. Results showed no significant differences in jump height between measurement methods (g = 0.00) or RSI_Mod (g = -0.49), although a significant difference was evident for time to take-off (g = 0.68). When a correction factor was applied to time to take-off data, no meaningful differences were evident (g = 0.00), which also had a knock-on effect for RSI_Mod (g = 0.10). Bland-Altman analysis showed near perfect levels of agreement for jump height with a bias estimate of 0.001 m, whilst time to take-off reported a bias estimate of 0.075 s initially and, 0.000 s once the correction factor was applied. For RSI_Mod, bias estimate was initially -0.048, and 0.006 once calculated with the corrected time to take-off data. Pearson’s r correlations were: 0.98 for jump height, 0.81 for time to take-off, and 0.85 for RSI_Mod. Based on the findings from the present study, and with the inclusion of the newly embedded correction factor, My Jump Lab can now be used as both a valid and reliable means of measuring time to take-off and RSI_Mod in the CMJ.

Key words

  • app
  • biomechanics
  • jump strategy
  • profiling
Open Access

The Effect of Aquatic Plyometric Training on Jump Performance Including a Four-week Follow-up in Youth Female Volleyball Players

Published Online: 08 Sep 2022
Page range: 197 - 205

Abstract

Abstract

This study aimed to analyze the effect of aquatic plyometric training (APT) on jump performance in volleyball players. Twelve female athletes (16.6 ± 0.9 years) were assessed through the following jump tests: spike height (SH), squat jump (SJ), countermovement jump (CMJ) and CMJ with an arm swing (CMJA). Jump height in each test and the eccentric utilization ratio (EUR) were the outcome measures. APT consisted of sets of drop jumps for 6 weeks (2 sessions/week) at a water depth of 0.75 m. Tests were performed at the beginning of a five-week pre-season period, before and after APT, and four weeks later for the follow-up. Repeated measures ANOVAs were used to analyze data and Hedges’ g to estimate effect size (ES). Performance of all jumps did not change from baseline to Pre-APT. Performance improved in SH (p < 0.001, ES: 1.09), the SJ (p = 0.045, ES: 0.76) and the CMJA (p < 0.001, ES: 0.78) after APT when compared to Pre-APT. No changes were observed after the follow-up period. In conclusion, including six weeks of APT in the training routine of youth volleyball players improved performance of a sport-specific task (SH), the SJ and CMJA, with gains preserved after a four-week follow-up.

Key words

  • power training
  • aquatic exercise
  • spike height
Open Access

The Distribution of Match Physical Activities Relative to the Most Demanding Scenarios in Professional Basketball Players

Published Online: 08 Sep 2022
Page range: 207 - 221

Abstract

Abstract

The purpose of this study was to examine the distribution of physical activities relative to the most demanding scenarios across playing positions during official basketball match-play. Twelve professional basketball players were monitored during twelve matches using a local positioning system. Peak physical demands were measured via total distance covered, distance covered >18 km·h-1, and the number of accelerations and decelerations >3 m·s-2 captured over 30- and 60-s rolling averages. The results showed that players were exposed to more than one high-demanding scenario in all variables and time epochs examined. Additionally, total distance covered presented the greatest number of moderate-demanding scenarios (40-80% of most demanding scenarios), whereas distance covered >18 km·h-1, and accelerations and decelerations >3 m·s-2 presented the greatest proportion of low-demanding scenarios (<40% of most demanding scenarios). Regarding positional differences, backcourt players generally experienced a higher number of scenarios than frontcourt players in most variables, especially in total distance covered. For this variable, scenarios between 20 and 70% of most demanding scenarios during the 30-s epoch (p < 0.001; ES = 0.420.78), and scenarios between 50 and 90% of most demanding scenarios during the 60-s epoch (p < 0.001; ES = 0.400.64) showed significant differences between backcourt and frontcourt players. Our data suggest that match physical activities are position-dependent and variable-dependent. In addition, peak physical demands appear to be repeated during basketball competition. These results may be considered by practitioners to complement average values and most demanding scenarios when prescribing individualized training programs to optimize team performance.

Key words

  • team sport
  • competition
  • technology
  • external load
Open Access

A Comparison of Electromyographic Inter-Limb Asymmetry during a Standard versus a Sling Shot Assisted Bench Press Exercise

Published Online: 08 Sep 2022
Page range: 223 - 234

Abstract

Abstract

The objective of this study was to compare peak surface electromyography (sEMG) activity of selected muscles along with inter-limb asymmetries between a control (CONT) and a Sling shot assisted (SS) bench press exercise. Ten resistance-trained males with at least three-year experience in resistance training (22.2 ± 1.9 years, 88.7 ± 11.2 kg, 179.5 ± 4.1 cm, bench press one-repetition maximum (1RM) = 127.3 ± 25.9 kg) performed the flat bench press exercise under two conditions at selected loads (85% and 100% of 1RM assessed without the SS). Peak sEMG amplitude of triceps brachii, pectoralis major, and anterior deltoid was recorded for the dominant and the non-dominant side of the body during each attempt. The comparison between the dominant and the non-dominant side was carried out using the limb symmetry index (LSI(%) = (2*(XR - XL)/(XR + XL))*100%) where XR = values of the right side and XL = values of the left side. There was a main effect of condition (p = 0.004; η2 = 0.64) and the load (p = 0.004; η2 = 0.63) for the triceps brachii LSI in parallel with a main effect of condition (p = 0.003; η2 = 0.42) for the anterior deltoid LSI. Post hoc analysis for the main effect of condition showed significant differences in the LSI between the CONT and SS conditions for the triceps brachii (p = 0.003; 1.10% vs. -8.78%) as well as for the anterior deltoid muscles (p = 0.03; 12.91% vs. 9.23%). The results indicate that the assistance of the Sling shot significantly affects the sEMG activity pattern on both the dominant and non-dominant sides of the body while influencing inter-limb asymmetries.

Key words

  • resistance exercise
  • EMG
  • training equipment
  • limb symmetry index
  • internal movement structure
Open Access

Blood-Flow-Restriction-Training-Induced Hormonal Response is not Associated with Gains in Muscle Size and Strength

Published Online: 08 Sep 2022
Page range: 235 - 243

Abstract

Abstract

The aim of this study was to determine whether increases in post-exercise endocrine response to low-load resistance exercise with blood flow restriction and high-load resistance exercise would have association with increases in muscle size and strength after an 8-week training period. Twenty-nine untrained men were randomly allocated into three groups: low-load resistance exercise with (LL-BFR) or without blood flow restriction (LL), and high-load resistance exercise (HL). Participants from LL-BFR and LL groups performed leg extension exercise at 20% of one repetition maximum (1RM), four sets of 15 repetitions and the HL group performed four sets of eight repetitions at 80% 1RM. Before the first training session, growth hormone (GH), insulin-like growth factor 1 (IGF-1), testosterone, cortisol, and lactate concentration were measured at rest and 15 min after the exercise. Quadriceps CSA and 1RM knee extension were assessed at baseline and after an 8-week training period. GH increased 15 min after exercise in the LL-BFR (p = 0.032) and HL (p < 0.001) groups, with GH concentration in the HL group being higher than in the LL group (p = 0.010). There was a time effect for a decrease in testosterone (p = 0.042) and an increase in cortisol (p = 0.005), while IGF-1 remained unchanged (p = 0.346). Both muscle size and strength were increased after training in LL-BFR and HL groups, however, these changes were not associated with the acute post-exercise hormone levels (p > 0.05). Our data suggest that other mechanisms than the acute post-exercise increase in systemic hormones induced by LL-BFR and HL produce changes in muscle size and strength.

Key words

  • resistance training
  • anabolic hormones
  • hypertrophy
  • vascular occlusion
  • cross-sectional area
  • muscle force
Open Access

Functional Performance Tests, On-Ice Testing and Game Performance in Elite Junior Ice Hockey Players

Published Online: 08 Sep 2022
Page range: 245 - 256

Abstract

Abstract

This study aimed to explore relationships between fitness, on-ice physical abilities and game performance among elite junior male ice hockey players. Twenty-one major junior ice hockey players (18.9 ± 1.4 years old) participated in the study. Measures including five fitness tests (anthropometric measures, pull up test, bench press test, broad jump, vertical jump) and three on-ice skating tests (multi-stage aerobic skating test, 44-m sprint test, and backward skating test) were assessed during their pre-season training camp. Game performance metrics (collected during the regular season) were collected using InStat software. Results of the (on-ice and off-ice) functional performance test protocol and on-ice tests were analyzed by evaluating correlation coefficients in multiple areas of game performance: 1) physical implication (body checks), 2) offensive contribution (expected goals for, types of zone entries), and 3) defensive actions (blocked shots, expected goals against). They revealed that performance in the broad jump test was associated with skating speed. Some significant correlations were also observed between on-ice test performance indicators such as received body checks, expected goals and blocked shots. In summary, results indicate that on-ice test protocols were associated with players’ performance in multiple aspects of the game. Partial correlation analyses revealed that some of these relationships were specific to the player's position. Forward skating was associated with forwards’ offensive play, and backward skating was specifically related with defensemen’s performance (offense and defense). The addition of on-ice physical tests appears essential for interpreting the results of ice hockey players' physical tests and integrating these results into players’ physical preparation and the in-season follow-up.

Key words

  • fitness assessment
  • elite ice hockey
  • hockey analytics
  • game performance
Open Access

Physical Performance Indicators and Team Success in the German Soccer League

Published Online: 08 Sep 2022
Page range: 257 - 265

Abstract

Abstract

The aims of this study were (1) to determine the match running performance required by different teams based on their final ranking position and (2) to analyze the association between match running performance variables and team success at the end of the season. A total of 1,224 match observations from professional soccer teams competing during two consecutive seasons in the German Bundesliga were analyzed. In addition, the final league ranking position and the total of points obtained by each team at the end of the season were registered for the analysis of the association between team success and match running performance. The main findings were that high ranked teams covered the greatest total distance with ball possession, sprinting distance with ball possession, and completed the greatest number of sprinting actions with ball possession and maximal velocity. Moreover, total distance covered with possession of the ball and maximal velocity were the most important variables to predict the total of points obtained at the end of the season. Specifically, the relative contribution of total distance covered with ball possession to the total of points obtained was greater than maximal velocity. Training programs for professional soccer players should be focused on improving the sprint capacity and running with possession of the ball (e.g., transitional tasks and small-sided games). Moreover, this has implications for injury prevention, physical, psychological, and technical-tactical training since today’s soccer requires players to engage in repeated high-intensity actions, reach maximum speeds above 9 m/s, and develop technical-tactical coordination when running with the ball.

Key words

  • match analysis
  • tracking systems
  • external load
  • monitoring
  • European football
Open Access

Sensitivity of Field Tests for Assessment of Wrestlers Specific Fitness

Published Online: 08 Sep 2022
Page range: 267 - 276

Abstract

Abstract

The aim of this study was to determine the differences in performance, cardiac, and metabolic variables of combat-specific fitness of wrestlers from varying sports levels. The sample consisted of 61 active and highly trained adult wrestlers of national and international levels from Serbia, from both Greco-Roman and freestyle forms of wrestling, allocated into three groups: national team wrestlers (N = 15), first league competitive wrestlers (N = 20), and second league competitive wrestlers (N = 26). Participants performed two tests: a Specific Wrestling Fitness Test (SWFT) and a Specific Wrestling Performance Test (SWPT). Between-group differences were determined using multiple analysis of variance (MANOVA). Significant differences were obtained between wrestlers of different sports levels in TnThrows (F = 77.491, p < 0.001), SJFIndex (F = 49.710, p < 0.001), and SWPIndex (F = 31.205, p < 0.001) in the SWFT and in TnThrows (F = 71.051, p < 0.001), SJFIndex F = 45.343, p < 0.001), and SWPIndex (F = 26.820, p < 0.001) in the SWPT. Based on the results, it could be concluded that the SWFT and the SWPT provide very good sensitivity in the evaluation of the wrestlers specific fitness of wrestlers.

Key words

  • combat sports
  • wrestling
  • testing
  • discriminative
Open Access

Performance and Submaximal Adaptations to Additional Speed-Endurance Training vs. Continuous Moderate-Intensity Aerobic Training in Male Endurance Athletes

Published Online: 08 Sep 2022
Page range: 277 - 285

Abstract

Abstract

We examined performance and submaximal adaptations to additional treadmill-based speed-endurance training (SET) vs. continuous moderate-intensity aerobic training (MIT) twice / week. Twenty-two male endurance athletes were tested before and after 10-week SET (6-12 × 30-s sprints separated by 3-min rest intervals) and MIT (2040 min continuous running at ~70% maximal oxygen uptake [V̇O2max]). The SET group attained greater acute heart rate (HR) and blood lactate responses than the MIT group (d = 0.86–0.91). The SET group improved performance in a time-to-exhaustion trial, V̇O2max, and lactate threshold (d = 0.50–0.73), whereas no training-induced changes were observed in the MIT group. Additionally, the SET group reduced oxygen uptake, mean HR and improved running economy (d = 0.53–0.86) during running at 10 and 12 km·h-1. Additional SET imposes greater physiological demands than MIT resulting in superior performance adaptations and reduced energy cost in endurance athletes.

Key words

  • anaerobic training
  • maximal oxygen uptake
  • blood lactate
  • submaximal exercise
  • performance
Open Access

Better Offensive Strategy in Basketball: A Two-Point or a Three-Point Shot?

Published Online: 08 Sep 2022
Page range: 287 - 295

Abstract

Abstract

To better understand and explore the development trend of the offensive strategies of the world’s top basketball leagues, this study took NBA shooting data in the regular seasons from 2009/2010 to 2018/2019 as the samples and analysed the relationships between the shooting score ratio and game win probability, and the practical application of offensive strategies in games. The results showed that (1) increasing the number and the percentage of three-point offenses in the game can improve the probability of winning. However, too many two-point shots can affect the team’s winning probability to a certain extent. (2) The strong teams in the NBA focused more on the outside offense, while the weak teams focused more on the inside offense. (3) Statistical data further showed that whether a team’s opponent is strong or weak, taking the offensive strategy that tends toward the outside shot can lead to a higher game win probability than the offensive strategy that tends toward the inside offense.

Key words

  • basketball
  • NBA
  • offense strategy
  • outside offense
  • inside offense
28 Articles

Section I - Kinesiology

Open Access

Kinematic Factors Associated with Hitting Hurdles during the Initial Phase of a 110-m Hurdle Race

Published Online: 08 Sep 2022
Page range: 5 - 12

Abstract

Abstract

This study aimed to clarify the kinematic factors for the cause and effect of hitting hurdles during the initial phase of a 110-m hurdle run. Nine experienced male hurdlers participated in this study (body height: 1.74 ± 0.04 m, body mass: 67.4 ± 5.9 kg, age: 20.2 ± 1.4 years, personal best: 15.21 ± 0.47 s, seasonal best: 15.33 ± 0.55 s). Hurdlers undertook 12 trials of the initial phase of hurdling from the start to the second hurdle landing. Dual-sided sagittal plane motion was obtained from images from two high-speed cameras operating at 120 Hz. One ‘hit’ trial which had the largest horizontal displacement of markers fixed on the hurdle and one ‘non-hit’ trial which had the fastest time of hurdle clearance were extracted for each participant. Kinematic variables were compared between the two trials. Significantly lower height of the whole-body centre of mass at the take-off was found as a possible cause of hitting hurdles, caused by insufficient swing-up of the lead leg thigh. In contrast to conventional understanding, take-off velocity, take-off distance and the take-off angle were comparable between the ‘hit’ trial and ‘non-hit’ trial. Regarding the effect of hitting hurdles, it was observed that running velocity during hurdling was not substantially reduced. However, several characteristic movements were identified that might induce inefficient motion to re-accelerate running velocity during the following landing steps.

Key words

  • motion analysis
  • athletics
  • kinematics
Open Access

The Effect of Arm Dominance on Knee Joint Biomechanics during Basketball Block Shot Single-Leg Landing

Published Online: 08 Sep 2022
Page range: 13 - 21

Abstract

Abstract

Single arm blocking is a key component of successful basketball defence. The player uses either their dominant or non-dominant arm to block the ball landing on a common leg. Understanding how the bio-physical loads of the landing leg change as a function of the blocking arm will provide insights into potential injury risk of the lower limb. The aim of this study was to investigate the effects of arm dominance on the biomechanical variables of injury risk of the lower limb, specifically the knee joint during the single-leg landing in female basketball players. Kinematic and kinetic data were collected from fourteen female basketball athletes (20.85 ± 1.35 years, 1.69 ± 0.06 m, 60.37 ± 7.75 kg), each performing three trials of a dominant arm and non-dominant block jump landing on the dominant leg. The results showed significantly higher anterior and medial ground reaction force, knee joint flexion and abduction and lateral knee force during the dominant arm landing (p < 0.05). These findings highlight potential injury risk and the need for the player to be more proficient at dominant arm block-shot landing. The player should aim to develop a larger landscape of technique to meet the demands of the game and facilitate a more effective and safer landing strategy.

Key words

  • anterior cruciate ligament injury
  • arm movement
  • basketball
  • knee joint biomechanics
Open Access

Biomechanical Adjustments of the Basketball Jump Shot Performed over Differently High Opponents

Published Online: 08 Sep 2022
Page range: 23 - 28

Abstract

Abstract

Biomechanical adjustments of the jump shot in presence of an opponent and their associations with shooting efficiency remain to be determined in elite basketball. The aim of this research was to examine the selected biomechanical determinants of the jump shot when shooting over opponents of different height. Nineteen elite basketball players, age 22 ± 3 years, performed three trials of 20 basketball shots in a crossover, randomised manner: over an obstacle of the height of standing reach (RH), over reach height with additional 20 cm (RH+20 cm), over reach height with additional 40 cm (RH+40 cm), and the maximum height jump shot without an obstacle (JSmax). Jump height, the ball entry angle, and shooting efficiency were measured on each trial. Jump height when shooting over RH+40 cm was significantly higher than RH+20 cm (+0.022 m, p = 0.030) and RH (+0.023 m, p = 0.029). Similarly, the ball entry angle was greater at RH+40 cm compared to RH (+7.19 °, p < 0.001) and RH+20 cm (+2.90°, p < 0.001). In contrast, shooting efficiency decreased significantly when shooting over RH+40 cm compared to RH (-10.79%, p = 0.048) and RH+20 cm (-8.95%, p = 0.015). We recorded the highest jump height (0.35 ± 0.08m, p < 0.001) and the lowest angle of entry (39.16 ± 1.19°, p < 0.001) when participants performed JSmax. Shooting over higher opponents should be prioritised in training to significantly improve shooting efficiency. Future research is needed to determine additional potential biomechanical determinants of a successful jump shot in elite basketball.

Key words

  • kinematics
  • jump shot
  • shooting angle
  • efficiency
  • basketball performance
Open Access

Effects of Leg Stiffness Regulated by Different Landing Styles on Vertical Drop Jump Performance

Published Online: 08 Sep 2022
Page range: 29 - 37

Abstract

Abstract

The purpose of this study was to investigate the effects of stiffness regulated by landing styles on drop jump performance. Twenty-four male lacrosse athletes performed drop jumps with stiff (ST), self-selected (SS), and soft (SF) landing from a 0.42 m box. Leg stiffness, ground contact time, depth, jump height, maximum ground reaction force (GRF), GRF at the start of the propulsive phase, mean power, peak power, and the reactive strength index (RSI) were calculated. The results showed that jump height and the RSI had strong correlations to power production in all drop jump styles. Power would be a key factor to overall athletic performance. Repeated measures ANOVA showed significant differences (p < 0.05) in all variables among the three styles. Drop jumps with SS landing had comparable jump height to drop jumps with SF landing and power output to drop jumps with ST landing. Drop jumps with ST landing had significantly lower jump height, but higher GRF, power, and the RSI compared to drop jumps with SF landing. In drop jump testing, drop jumps with SS landing should be used if power and jump height were the major concerns; if the RSI was the major concern, drop jumps with ST landing should be used. Training with drop jumps, one of the main objectives should be increasing power output due to its significant correlation to jump height and the RSI in all conditions.

Key words

  • stretch-shortening cycle
  • stiff
  • soft
  • power
  • reactive strength
Open Access

Contributing Factors to Sensorimotor Adaptability in Reactive Agility Performance in Youth Athletes

Published Online: 08 Sep 2022
Page range: 39 - 48

Abstract

Abstract

Sensorimotor adaptability facilitates adjusting behaviour for changing environmental stimuli to maintain appropriate goal-directed motor performance. Its effectiveness is associated with perceptual-cognitive modulation. As the factors affecting it are still not completely known, the aim of our study was therefore to analyse the association between selected variables (demographic, training, anthropometric, genetic) and sensorimotor adaptation in reactive agility tasks in youth team-sport athletes. The study group consisted of 85 youth athletes (aged 12.61 ± 0.98 years). Based on an initial evaluation, participants were divided into faster and slower agility groups. The resultant differences between change of direction speed tests and reactive agility tests provided the REAC-INDEX as a dependent variable. The independent variables were as follows: gender, calendar age, body mass, height, BMI, maturity offset, training status and the BDNF rs6265 polymorphism. Multiple linear regression showed that the maturity offset (ß = 0.269; p = 0.012) and calendar age (ß = -0.411; p < 0.001) significantly contributed to the REAC-INDEX of all participants (R2 = 0.13). In the slower group, the c.196G BDNF allele had a significant influence (ß = -0.140; p = 0.044) on the REAC-INDEX. The best predictive model comprised female gender (ß = 0.799; p < 0.001), maturity offset (ß = -0.586; p < 0.001) and training experience (ß = -0.225; p = 0.009), contributing to 49% of RA variance. Sensorimotor adaptability is mainly dependent on gender and age, and can be improved through systematic sports training. The BDNF rs6265 polymorphism may be considered a contributing factor to SA variability in the initial stages of training, although polymorphism-related differences blurred as the effect of participation in sports training increased.

Key words

  • gender
  • maturity
  • age
  • brain-derived neurotrophic factor
  • team sport games

Section II - Exercise Physiology & Sports Medicine

Open Access

Does the Self‐Myofascial Release Affect the Activity of Selected Lower Limb Muscles of Soccer Players?

Published Online: 08 Sep 2022
Page range: 49 - 57

Abstract

Abstract

Myofascial therapy has already become one of the basic forms of treatment of the locomotor system. One form of the therapy is Self-Myofascial Release, in which external force is applied to the body with the help of special rollers (foam rolling, FR). The aim of the study was to investigate the direct effect of Self-Myofascial Release of hamstring muscles using a foam roller on the bioelectric activity of selected muscles (biceps femoris and gluteus maximus) during squats. The study involved 40 male soccer players, who were randomly divided into two groups: experimental and control. The tests used did not show significant differences in the analyzed variables before the experiment (baseline measurement p > 0.05), while significant intergroup differences appeared for subsequent measurements, both for reference MVC values (p < 0.01 - for % gluteus maximus MVC, p < 0.001 - for % biceps femoris MVC) and for raw EMG values (p < 0.01 gluteus maximus and p < 0.001 - for % 0.0001 for biceps femoris). The use of self-myofascial release within the hamstring muscles leads to changes in the electrical potential of the muscles of the lower limb.

Key words

  • electromyography
  • foam rolling
  • hamstring
  • soccer
  • myofascial self-release
Open Access

Evaluation of Water Intake in Spanish Adolescent Soccer Players during a Competition

Published Online: 08 Sep 2022
Page range: 59 - 66

Abstract

Abstract

An optimal state of hydration is essential to maintaining health. The objective of this cross-sectional study was to evaluate the water intake of adolescents aged 12 to 16 years and their hydration level during an official soccer match. Three hundred and six players participated in the study (N = 306). Their water intake was recorded and the level of hydration was evaluated using the density of urine as an indicator. Weight measurements were made before and after the match. Water intake control, urine collection and analysis, and the recording of minutes played were carried out after the match. The average weight loss was 746.2 g (SD: 474.07; p < 0.001), with 36.5% with less than 1% loss and 23.3% with more than 2% loss. The mean volume of water ingested was 229.35 ml (SD: 211.11) and a significant correlation was observed between minutes of activity (ρ-value = 0.206; p < 0.001), environmental humidity (ρ-value = - 0.281; p < 0.001), and temperature (ρ-value = 0.200; p < 0.001). The sweat rate was 0.69 l/h (SD: 0.56) and it was significantly associated with playing time (ρ-value = -0.276; p < 0.001). The mean urine density was 1.019 (SD: 0.007), with 64.9% of youth athletes showing dehydration (≥ 1.020). An association was observed between dehydration and activity time (U- value = 4.124; p < 0.001). Approximately 10% of the participants stated that they had not drunk any water during the match. In conclusion, it is necessary to establish individual hydration guidelines based on personal, environmental and activity-related factors, as well as establish a minimum volume of fluids to consume.

Key words

  • soccer
  • adolescent
  • hydration status
  • water intake
Open Access

Myofascial and Movement Tests after Anterior Cruciate Ligament Reconstruction

Published Online: 08 Sep 2022
Page range: 67 - 75

Abstract

Abstract

Functional evaluation after anterior cruciate ligament reconstruction is one of the key points involved in decision making about the return of patients to full and unrestricted physical activity. The objective of the present study was to verify whether myofascial chain NEURAC® and Functional Movement Screen (FMS™) tests can be used to detect functional differences between the operated and the non-operated extremity in patients after anterior cruciate ligament reconstruction. A total of 83 young and physically active recreational athletes (mean age: 26.9 ± 9.7 years) who underwent primary single-bundle anterior cruciate ligament reconstruction using an autogenous semitendinosus-gracilis tendon graft were evaluated between the 3rd and the 4th month after surgery. Subjects received a similar, standardised rehabilitation programme. Two experienced raters, blinded to the objective of this study, were involved in functional outcome data collection using myofascial NEURAC® and Functional Movement Screen tests. Only two of the NEURAC® tests showed significant differences in the results between the operated and the non-operated extremity: the supine bridging (mean 2.92 vs. 3.51 points, p < 0.001) and prone bridging (mean 2.76 vs. 3.67 points, p < 0.001) tests. Additionally, the summary score of all NEURAC® tests significantly differed between extremities (mean 12.08 for the operated vs. 13.67 points for the non-operated extremity, p < 0.001). Myofascial tests (supine and prone bridging) in comparison with a battery of Functional Movement Screen tests seem to be more effective in detecting functional differences between the operated and the non-operated extremity at the early stage of recovery after anterior cruciate ligament reconstruction.

Key words

  • functional performance
  • NEURAC® myofascial tests
  • Functional Movement Screen™ tests
  • return to sport criteria
Open Access

Validity and Reliability of New Equations for the Prediction of Maximal Oxygen Uptake in Male and Female Elite Adolescent Rowers

Published Online: 08 Sep 2022
Page range: 77 - 86

Abstract

Abstract

The aim of this study was to develop accurate, reliable, and reproductive equations for the prediction of maximum oxygen uptake ( V ˙ $\dot{V}$O2max) in male and female high-level adolescent rowers. This study included two parts. In the first part, V̇O2max was evaluated in 106 male and 83 female high-level adolescent rowers during an incremental step test (IRT) on a rowing ergometer, and stepwise multiple regression analyses were used for the development of new equations. In the second part, these equations were tested in 26 new high-level adolescent rowers of the same age and anthropometrical characteristics (boys: 15.27 ± 2.70 yrs and 15.34 ± 2.80 yrs; 72.37 ± 10.96 kg and 70.96 ± 10.65 kg; girls: 15.00 ± 2.11 yrs and 15.94 ± 2.71 yrs; 62.50 ± 7.14 kg and 63.41 ± 6.72 kg for parts 1 and 2, respectively; p > 0.05). V̇O2max was predicted from the combination of lean body mass (LBM) and the distance covered during the last 4 min stage of the IRT (boys: r2 = 0.715, F = 68.74, p = 0.001; girls: r2 = 0.769, F = 57.81, p = 0.001). In the second part, no significant differences were identified when the new equations were tested against measured V̇O2max (boys: 3971.15 ± 713.38 mL·min−1 vs. 3915.83 ± 704.43 mL·min−1; girls: 3272.75 ± 551.46 mL·min−1 vs. 3308.94 ± 557.59 mL·min−1 for measured and predicted values, respectively; p > 0.05). In conclusion, V̇O2max of high-level adolescent rowers can be predicted with high accuracy, reliability, and repeatability using simple and easily evaluated anthropometric and performance variables.

Key words

  • rowing performance
  • youth athletes
  • children
  • rowing test
  • maximal oxygen uptake
Open Access

Muscle Oxygen Saturation Breakpoints Reflect Ventilatory Thresholds in Both Cycling and Running

Published Online: 08 Sep 2022
Page range: 87 - 97

Abstract

Abstract

Pulmonary gas exchange analysis was compared to changes in muscle oxygen saturation as measured by near-infrared spectroscopy. First, ventilatory thresholds determined by common gas exchange analysis and breakpoints in muscle oxygen saturation were assessed for agreement during exercise with increasing intensity. Secondly, the relationship between muscle oxygen saturation as a surrogate for local oxygen extraction and peak oxygen uptake was assessed. In order to lend robustness to future NIRS testing on a broader scale, considering its potential for simple and cost-effective application, the question of a running versus a cycling modality was integrated into the design. Ten participants, of whom five were recreationally trained cyclists and five recreationally trained runners, were tested; each during a cycling test and a running test with increasing intensity to voluntary exhaustion. Muscle oxygen saturation and pulmonary gas exchange measurements were conducted. Bland-Altman analysis showed a moderate degree of agreement between both muscle oxygen saturation breakpoint 1 and muscle oxygen saturation breakpoint 2 and corresponding ventilatory threshold 1 and ventilatory threshold 2, for both cycling and running disciplines; generally speaking, muscle oxygen saturation breakpoints underestimated ventilatory thresholds. Additionally, a strong relationship could be seen between peak oxygen uptake and the minimally attained muscle oxygen saturation during cycling exercise. Muscle oxygen saturation measured using NIRS was determined to be a suitable method to assess ventilatory thresholds by finding breakpoints in muscle oxygen saturation, and muscle oxygen saturation minimum was linked to peak oxygen uptake.

Key words

  • NIRS
  • anaerobic threshold
  • tissue oxygen saturation
  • lactate threshold
Open Access

Effect of Beta-Alanine Supplementation on Exercise-Induced Cell Damage and Lactate Accumulation in Female Basketball Players: a Randomized, Double-Blind Study

Published Online: 08 Sep 2022
Page range: 99 - 107

Abstract

Abstract

Beta-alanine (BA) is a supplement that has received attention for its buffering potential among athletes. The aim of this study was to investigate the effects of BA supplementation on exercise performance and exercise-induced cell damage in female basketball players. Twenty-two female basketball players participated in a randomized, double-blind study. They ingested 6.4 g·day-1 of BA or an isocaloric placebo (dextrose) over 4 weeks. Exercise performance including aerobic (Bruce test), anaerobic (Wingate test), intermittent (Yo-Yo test) and basketball performance (countermovement jump and free throw shots) was measured before and following the intervention. Exercise measures were performed at the lab and free throw shots were undertaken on a wooden indoor basketball court. Blood samples were also collected before and after the exhaustive exercise to assess lactate concentration, creatine kinase (CK), lactate dehydrogenase (LDH) and malondialdehyde (MDA) activity. The exhaustive exercise test induced an increase in lactate concentration and MDA, CK and LDH activity (all p < 0.05). BA supplementation significantly reduced the lactate response to exhaustive exercise (p = 0.001); however, it had no significant effect on exercise-induced MDA, CK and LDH activity (all p > 0.05). Furthermore, exercise performance measures improved from pre- to post-test regardless of supplement/placebo ingestion (all p < 0.05). BA consumption over 4 weeks significantly reduced lactate accumulation following exhaustive exercise, but had no ergogenic effect in female basketball players. Usual dosing of BA does not seem to exhibit protective effect against oxidative damage.

Key words

  • buffering capacity
  • carnosine
  • oxidative damage
  • muscle damage
Open Access

Carbohydrate Rinse Fails to Enhance Cycling Performance or Alter Metabolic and Autonomic Recovery in Recreational Cyclists

Published Online: 08 Sep 2022
Page range: 109 - 119

Abstract

Abstract

The purpose of the study was to examine the effects of carbohydrate (CHO) mouth rinsing on autonomic and metabolic recovery as well as cycling performance. Ten male recreational cyclists (age = 30 ± 6 years, VO2peak = 54.5 ± 8.1 mL·kg-1·min-1) completed a randomized, double-blind, placebo-controlled, crossover designed study. A CHO or a placebo (PLA) rinse was administered every 12.5% of a work to completion trial (75%Wmax). Heart rate variability (lnRMSSD), the respiratory exchange ratio, and plasma epinephrine, norepinephrine, insulin, glucose, free fatty acids (FFA), and lactate were measured pre- and post-exercise. The CHO rinse did not improve time to completion of the test trial (CHO: 4108 ± 307 s, PLA: 4176 ± 374 s, p = 0.545). Further, the CHO rinse did not impact autonomic recovery, as measured by lnRMSSD (p = 0.787) and epinephrine (p = 0.132). Metabolic biomarkers were also unaffected by the CHO rinse, with no differences observed in responses of FFA (p = 0.064), lactate (p = 0.302), glucose (p = 0.113) or insulin (p = 0.408). Therefore, the CHO mouth rinse does not reduce the acute sympathetic response following strenuous exercise and does not result in improvements in cycling time to completion.

Key words

  • carbohydrate solution
  • endurance performance
  • cycling
  • heart rate variability
  • autonomic nervous system
  • exercise metabolism
Open Access

Submaximal Testing to Estimate Aerobic Capacity Using a Matrix C5x Stepmill

Published Online: 08 Sep 2022
Page range: 121 - 129

Abstract

Abstract

The primary purpose of this study was to determine if the Matrix C5x stepmill’s preprogrammed submaximal test is able to accurately predict maximal oxygen uptake. Sixteen participants completed a maximal treadmill test and a preprogrammed submaximal test on a Matrix C5x stepmill. Oxygen uptake was measured using a Cosmed K5 during both tests. Maximal oxygen uptake (VO2max) was calculated from submaximal data using a multi-stage calculation and compared against measured VO2max from the maximal test and estimated VO2max from the submaximal stepmill test. METs were also measured during the submaximal test and compared to the METs estimated by the stepmill and METs calculated using submaximal stepping equations. Measured VO2max (39.18 α 6.6 ml.kg-1.min-1) was significantly higher (p < 0.001) than estimated VO2max (28.06 α 3.2 ml.kg-1.min-1) and calculated VO2max (35.58 α 8.0 ml.kg-1.min-1). Measured METs were significantly (p = 0.04) higher than estimated METs in all stages, and higher than calculated METs in stage 1 of the submaximal test. The C5x did not provide accurate estimations of METs or maximal oxygen uptake. Calculating maximal oxygen uptake from submaximal stepmill data may provide an alternative, although development of a new equation may be warranted.

Key words

  • VO
  • METs
  • Watts
  • stair climbing
  • stepmill
Open Access

Effect of High‐Intensity, Intermittent, Short‐Duration Re‐Warming Up on Cycling Sprint Performance

Published Online: 08 Sep 2022
Page range: 131 - 141

Abstract

Abstract

The aim of this study was to investigate the effects of warming up again during half-time (i.e., re-warm up [RW]) with high-intensity, intermittent, short-duration exercise on cycling sprint performance. Participants (male, n = 10) performed intermittent cycling exercise for 40 min, followed by a 15-min half-time period with either rest only (control trials [CON]) or rest followed by a RW (three intervals of 3 s of maximal-effort cycling and 27 s of rest [HII]), after which participants performed the Cycling Intermittent-Sprint Protocol (CISP) to evaluate their sprint performance (17.0 ± 1.4°C, 44.2 ± 7.0% relative humidity). CISP intervals comprised 10 s rest, 5 s maximal effort cycling, and 105 s active recovery at 50% of the maximum oxygen uptake (VO2max) and were repeated 10 times. All participants performed both trial variations in randomized order. Peak power output of 5-s cycling sprints during the CISP were significantly higher in HII trials than those in CON trials (CON: 813 ± 109 W, HII: 836 ± 118 W, p < 0.05). Oxygen uptake, blood lactate concentration, and the rating of perceived exertion at the beginning of the second half after the RW were significantly higher in HII trials than those in CON trials (p < 0.05). These results demonstrate that the RW with intermittent, high-intensity, short-duration exercise improved subsequent cycling sprint performance in a thermoneutral environment and may represent a new useful RW strategy.

Key words

  • sports
  • sprinting
  • half-time
  • intermittent exercise
  • heart rate
  • blood lactate concentration
Open Access

Associations between Selected Biological Features and Absolute and Relative Swimming Performance of Prepubescent Boys over a 3‐Year Swimming Training Program: A Longitudinal Study

Published Online: 08 Sep 2022
Page range: 143 - 153

Abstract

Abstract

The study aimed to investigate the effect of 3-year swimming training on selected biological variables in prepubescent male swimmers and to determine the best predictors of absolute (VSa) and relative (VSr) swimming velocity for 50 m and 400 m front crawl. Twenty-one 10-year old boys subjected to endurance swimming training (4 x 70 min per week) and 18 boys consisting a control group were assessed semi-annually for basic anthropometric and respiratory characteristics, breath-hold time (BHT), VO2max, leg explosiveness (HJ), and abdominal strength endurance (ASE). After three years of training, BHT (p < 0.001), VO2max (p < 0.01), HJ (p < 0.01) and ASE (p < 0.01) were greater in the swimmers than in the controls. VSa and VSr expressed as a percentage of baseline velocity increased more for the 50 m than for the 400 m distance (p < 0.001 and p < 0.01, respectively). The 50 m VSa and VSr positively correlated with those obtained for the distance of 400 m (in both cases p < 0.001). Baseline VSa was negatively correlated with the increase in absolute swimming velocity for both distances (50 m: r = -0.684, p < 0.001 and 400 m: r = -0.673, p < 0.001). The best predictors of VSa for 50 m and 400 m front crawl were HJ (r2 = 0.388; p < 0.001) and VO2max (r2 = 0.333; p < 0.001), respectively. The key predictors of VSr for both distances were age (50 m: r2 = 0.340, p < 0.001 and 400 m: r2 = 0.207, p < 0.001) and, after excluding it from analysis, HJ (50 m: r2 = 0.176, p < 0.001 and 400 m: r2 = 0.104, p < 0.001). These results suggest that regardless of prepubescent boys’ initial abilities and exercise capacity, improvement in their swimming performance mainly depends on increases in power and neuromuscular coordination.

Key words

  • swimming performance
  • relative swimming velocity
  • physical capacity
  • prepubescent boys
  • longitudinal study
Open Access

Elite Rugby Players Have Unique Morphological Characteristics of the Hamstrings and Quadriceps Femoris Muscles According to their Playing Positions

Published Online: 08 Sep 2022
Page range: 155 - 163

Abstract

Abstract

Rugby is a popular sport requiring high-intensity and maximal speed actions. Numerous studies have demonstrated that physical performance variables, such as strength, sprinting, and jumping, are different between the forwards and backs. However, there is little information about muscle morphological characteristics specific for each rugby playing position. This study aimed to clarify the morphological characteristics of the thigh muscles in forwards and backs. Ultrasound images were obtained from the proximal, middle, and distal regions of the thigh. Then, the anatomical cross-sectional areas of particular muscles in the hamstrings and quadriceps femoris were calculated for seven forwards, seven backs, and ten non-athletes. The anatomical cross-sectional areas were normalised by the two-third power of lean body mass, and the normalised values of the three regions were averaged as that of the individual muscle. In the hamstrings, the normalised anatomical cross-sectional areas of the biceps femoris long head were significantly greater in forwards than in non-athletes, whereas those of the semitendinosus were significantly greater in backs than in non-athletes. Furthermore, in the quadriceps femoris, the normalised anatomical cross-sectional areas of the rectus femoris and vastus intermedius were significantly greater in forwards than in backs and non-athletes. These results suggest that forwards have great muscularity of the biceps femoris long head and vastus intermedius which can generate large force, whereas backs possess great muscularity of the semitendinosus which can generate high contraction velocity. These findings allow coaches to design more effective training programs according to particular rugby playing positions.

Key words

  • muscle size
  • forward
  • backs
  • ultrasonography

Section III – Sports Training

Open Access

External and Internal Training Loads for Intensive and Extensive Tactical-Conditioning in Soccer Small Sided Games

Published Online: 08 Sep 2022
Page range: 165 - 173

Abstract

Abstract

This study aimed to investigate the external (ETLs; 15-Hz GPS unit coupled with a 100 Hz tri-axial accelerometer) and internal training loads (ITLs; session-RPE method) of 18 elite U20 soccer players (19 ± 1.0 years, 178 ± 8 cm, 71 ± 7 kg) undertaking a tactical-conditioning training program with special reference to small-sided games (SSGs). The SSGs used in this program were either extensive (SSG-extensive) or intensive (SSG-intensive) training sessions, that were alternated within the assessed weeks. Tactical principles of the game influenced the aim of the technical-tactical content. Total distance (TDR; ES: 1.17), and a very high-speed running distance (HSR; ES: 0.96) were greater in SSG-extensive vs. SSG-intensive. However, no meaningful difference was found for accelerations (ACC; ES: 0.12) and decelerations (DEC; ES: 0.08). However, a higher perceived intensity (session-RPE; ES: 0.62) and greater ITLs (ES: 0.27) were found for SSG-intensive. These findings suggest that coaches should prescribe SSG training sessions not only considering the usual variables (rules, player numbers, etc.). The current data indicate that the tactical objective of SSGs in relation to exercise bout duration and rest intervals should be considered, while implementing a multi-dimensional training monitoring program during SSG tactical-conditioning training sessions, integrating ETL and ITL variables to gain a better understanding of training responses.

Key words

  • internal load
  • external load
  • game-based training
  • elite athletes
Open Access

External Workload Compared Between Competitive and Non-Competitive Matches for Professional Male Soccer Players

Published Online: 08 Sep 2022
Page range: 175 - 184

Abstract

Abstract

The purpose of this study was to compare the external load in competitive (official) and non-competitive matches (friendly, training and modified-sided games) in professional soccer players. Time-motion data for 10 elite male soccer players (age = 20.1 ± 2.1 years; body height = 178.8 ± 5.9; body mass = 71.4 ± 7.3; % body fat = 11.0 ± 1.1 and VO2max = 55.96 ± 3.3) from a professional Spanish first division team were recorded during official (n = 12), friendly (n = 7) and training (n = 6) matches and a 5 vs. 5 + goalkeepers modified-sided game (n = 3). GPS devices were used to monitor players’ external loads: total distance covered, distance covered at different speeds (<13.9 km·h-1, >14, >18, >21 and >25 km·h-1), peak speed (km·h-1), and the number of accelerations and decelerations (1.5–2.5 m·s-2, 2.5–4 m·s-2 and 4–8 m·s-2). One-way analysis of variance of the magnitude-based inference was used to determine differences between matches. Data indicated that official matches scored statistically higher peak speeds (ES = 1.40–2.20). In modified-sided games more total distance was covered at <13.9 km·h-1 and >14 km·h-1 than in regular matches (ES = 0.72–2.21), but lower distances were covered at >21 km·h-1 and >25 km·h-1 than in official and friendly matches (ES = 0.51–2.53) and at >25 km·h-1 than in training matches (ES = 0.92). Likewise, the modified-side games showed a greater number of accelerations and decelerations than other types of matches (ES = 1.46–2.51). This work shows that friendly and training matches, in conjunction with modified-side games, are suitable tools to prepare soccer players for official matches.

Key words

  • soccer
  • training
  • small-sided games
  • GPS
  • time-motion analyses
Open Access

Validity and Reliability of Strategy Metrics to Assess Countermovement Jump Performance Using the Newly Developed My Jump Lab Smartphone Application

Published Online: 08 Sep 2022
Page range: 185 - 195

Abstract

Abstract

The aim of the present study was to analyse the validity and reliability of the newly developed My Jump Lab smartphone app, which includes the option to calculate time to take-off and the reactive strength index modified (RSI_Mod – calculated as jump height divided by time to take-off), in addition to jump height. Twenty-seven postgraduate sport science students attended a single test session and performed three maximal effort countermovement jumps (CMJ) on twin force plates, whilst concurrently being filmed using the app. Results showed no significant differences in jump height between measurement methods (g = 0.00) or RSI_Mod (g = -0.49), although a significant difference was evident for time to take-off (g = 0.68). When a correction factor was applied to time to take-off data, no meaningful differences were evident (g = 0.00), which also had a knock-on effect for RSI_Mod (g = 0.10). Bland-Altman analysis showed near perfect levels of agreement for jump height with a bias estimate of 0.001 m, whilst time to take-off reported a bias estimate of 0.075 s initially and, 0.000 s once the correction factor was applied. For RSI_Mod, bias estimate was initially -0.048, and 0.006 once calculated with the corrected time to take-off data. Pearson’s r correlations were: 0.98 for jump height, 0.81 for time to take-off, and 0.85 for RSI_Mod. Based on the findings from the present study, and with the inclusion of the newly embedded correction factor, My Jump Lab can now be used as both a valid and reliable means of measuring time to take-off and RSI_Mod in the CMJ.

Key words

  • app
  • biomechanics
  • jump strategy
  • profiling
Open Access

The Effect of Aquatic Plyometric Training on Jump Performance Including a Four-week Follow-up in Youth Female Volleyball Players

Published Online: 08 Sep 2022
Page range: 197 - 205

Abstract

Abstract

This study aimed to analyze the effect of aquatic plyometric training (APT) on jump performance in volleyball players. Twelve female athletes (16.6 ± 0.9 years) were assessed through the following jump tests: spike height (SH), squat jump (SJ), countermovement jump (CMJ) and CMJ with an arm swing (CMJA). Jump height in each test and the eccentric utilization ratio (EUR) were the outcome measures. APT consisted of sets of drop jumps for 6 weeks (2 sessions/week) at a water depth of 0.75 m. Tests were performed at the beginning of a five-week pre-season period, before and after APT, and four weeks later for the follow-up. Repeated measures ANOVAs were used to analyze data and Hedges’ g to estimate effect size (ES). Performance of all jumps did not change from baseline to Pre-APT. Performance improved in SH (p < 0.001, ES: 1.09), the SJ (p = 0.045, ES: 0.76) and the CMJA (p < 0.001, ES: 0.78) after APT when compared to Pre-APT. No changes were observed after the follow-up period. In conclusion, including six weeks of APT in the training routine of youth volleyball players improved performance of a sport-specific task (SH), the SJ and CMJA, with gains preserved after a four-week follow-up.

Key words

  • power training
  • aquatic exercise
  • spike height
Open Access

The Distribution of Match Physical Activities Relative to the Most Demanding Scenarios in Professional Basketball Players

Published Online: 08 Sep 2022
Page range: 207 - 221

Abstract

Abstract

The purpose of this study was to examine the distribution of physical activities relative to the most demanding scenarios across playing positions during official basketball match-play. Twelve professional basketball players were monitored during twelve matches using a local positioning system. Peak physical demands were measured via total distance covered, distance covered >18 km·h-1, and the number of accelerations and decelerations >3 m·s-2 captured over 30- and 60-s rolling averages. The results showed that players were exposed to more than one high-demanding scenario in all variables and time epochs examined. Additionally, total distance covered presented the greatest number of moderate-demanding scenarios (40-80% of most demanding scenarios), whereas distance covered >18 km·h-1, and accelerations and decelerations >3 m·s-2 presented the greatest proportion of low-demanding scenarios (<40% of most demanding scenarios). Regarding positional differences, backcourt players generally experienced a higher number of scenarios than frontcourt players in most variables, especially in total distance covered. For this variable, scenarios between 20 and 70% of most demanding scenarios during the 30-s epoch (p < 0.001; ES = 0.420.78), and scenarios between 50 and 90% of most demanding scenarios during the 60-s epoch (p < 0.001; ES = 0.400.64) showed significant differences between backcourt and frontcourt players. Our data suggest that match physical activities are position-dependent and variable-dependent. In addition, peak physical demands appear to be repeated during basketball competition. These results may be considered by practitioners to complement average values and most demanding scenarios when prescribing individualized training programs to optimize team performance.

Key words

  • team sport
  • competition
  • technology
  • external load
Open Access

A Comparison of Electromyographic Inter-Limb Asymmetry during a Standard versus a Sling Shot Assisted Bench Press Exercise

Published Online: 08 Sep 2022
Page range: 223 - 234

Abstract

Abstract

The objective of this study was to compare peak surface electromyography (sEMG) activity of selected muscles along with inter-limb asymmetries between a control (CONT) and a Sling shot assisted (SS) bench press exercise. Ten resistance-trained males with at least three-year experience in resistance training (22.2 ± 1.9 years, 88.7 ± 11.2 kg, 179.5 ± 4.1 cm, bench press one-repetition maximum (1RM) = 127.3 ± 25.9 kg) performed the flat bench press exercise under two conditions at selected loads (85% and 100% of 1RM assessed without the SS). Peak sEMG amplitude of triceps brachii, pectoralis major, and anterior deltoid was recorded for the dominant and the non-dominant side of the body during each attempt. The comparison between the dominant and the non-dominant side was carried out using the limb symmetry index (LSI(%) = (2*(XR - XL)/(XR + XL))*100%) where XR = values of the right side and XL = values of the left side. There was a main effect of condition (p = 0.004; η2 = 0.64) and the load (p = 0.004; η2 = 0.63) for the triceps brachii LSI in parallel with a main effect of condition (p = 0.003; η2 = 0.42) for the anterior deltoid LSI. Post hoc analysis for the main effect of condition showed significant differences in the LSI between the CONT and SS conditions for the triceps brachii (p = 0.003; 1.10% vs. -8.78%) as well as for the anterior deltoid muscles (p = 0.03; 12.91% vs. 9.23%). The results indicate that the assistance of the Sling shot significantly affects the sEMG activity pattern on both the dominant and non-dominant sides of the body while influencing inter-limb asymmetries.

Key words

  • resistance exercise
  • EMG
  • training equipment
  • limb symmetry index
  • internal movement structure
Open Access

Blood-Flow-Restriction-Training-Induced Hormonal Response is not Associated with Gains in Muscle Size and Strength

Published Online: 08 Sep 2022
Page range: 235 - 243

Abstract

Abstract

The aim of this study was to determine whether increases in post-exercise endocrine response to low-load resistance exercise with blood flow restriction and high-load resistance exercise would have association with increases in muscle size and strength after an 8-week training period. Twenty-nine untrained men were randomly allocated into three groups: low-load resistance exercise with (LL-BFR) or without blood flow restriction (LL), and high-load resistance exercise (HL). Participants from LL-BFR and LL groups performed leg extension exercise at 20% of one repetition maximum (1RM), four sets of 15 repetitions and the HL group performed four sets of eight repetitions at 80% 1RM. Before the first training session, growth hormone (GH), insulin-like growth factor 1 (IGF-1), testosterone, cortisol, and lactate concentration were measured at rest and 15 min after the exercise. Quadriceps CSA and 1RM knee extension were assessed at baseline and after an 8-week training period. GH increased 15 min after exercise in the LL-BFR (p = 0.032) and HL (p < 0.001) groups, with GH concentration in the HL group being higher than in the LL group (p = 0.010). There was a time effect for a decrease in testosterone (p = 0.042) and an increase in cortisol (p = 0.005), while IGF-1 remained unchanged (p = 0.346). Both muscle size and strength were increased after training in LL-BFR and HL groups, however, these changes were not associated with the acute post-exercise hormone levels (p > 0.05). Our data suggest that other mechanisms than the acute post-exercise increase in systemic hormones induced by LL-BFR and HL produce changes in muscle size and strength.

Key words

  • resistance training
  • anabolic hormones
  • hypertrophy
  • vascular occlusion
  • cross-sectional area
  • muscle force
Open Access

Functional Performance Tests, On-Ice Testing and Game Performance in Elite Junior Ice Hockey Players

Published Online: 08 Sep 2022
Page range: 245 - 256

Abstract

Abstract

This study aimed to explore relationships between fitness, on-ice physical abilities and game performance among elite junior male ice hockey players. Twenty-one major junior ice hockey players (18.9 ± 1.4 years old) participated in the study. Measures including five fitness tests (anthropometric measures, pull up test, bench press test, broad jump, vertical jump) and three on-ice skating tests (multi-stage aerobic skating test, 44-m sprint test, and backward skating test) were assessed during their pre-season training camp. Game performance metrics (collected during the regular season) were collected using InStat software. Results of the (on-ice and off-ice) functional performance test protocol and on-ice tests were analyzed by evaluating correlation coefficients in multiple areas of game performance: 1) physical implication (body checks), 2) offensive contribution (expected goals for, types of zone entries), and 3) defensive actions (blocked shots, expected goals against). They revealed that performance in the broad jump test was associated with skating speed. Some significant correlations were also observed between on-ice test performance indicators such as received body checks, expected goals and blocked shots. In summary, results indicate that on-ice test protocols were associated with players’ performance in multiple aspects of the game. Partial correlation analyses revealed that some of these relationships were specific to the player's position. Forward skating was associated with forwards’ offensive play, and backward skating was specifically related with defensemen’s performance (offense and defense). The addition of on-ice physical tests appears essential for interpreting the results of ice hockey players' physical tests and integrating these results into players’ physical preparation and the in-season follow-up.

Key words

  • fitness assessment
  • elite ice hockey
  • hockey analytics
  • game performance
Open Access

Physical Performance Indicators and Team Success in the German Soccer League

Published Online: 08 Sep 2022
Page range: 257 - 265

Abstract

Abstract

The aims of this study were (1) to determine the match running performance required by different teams based on their final ranking position and (2) to analyze the association between match running performance variables and team success at the end of the season. A total of 1,224 match observations from professional soccer teams competing during two consecutive seasons in the German Bundesliga were analyzed. In addition, the final league ranking position and the total of points obtained by each team at the end of the season were registered for the analysis of the association between team success and match running performance. The main findings were that high ranked teams covered the greatest total distance with ball possession, sprinting distance with ball possession, and completed the greatest number of sprinting actions with ball possession and maximal velocity. Moreover, total distance covered with possession of the ball and maximal velocity were the most important variables to predict the total of points obtained at the end of the season. Specifically, the relative contribution of total distance covered with ball possession to the total of points obtained was greater than maximal velocity. Training programs for professional soccer players should be focused on improving the sprint capacity and running with possession of the ball (e.g., transitional tasks and small-sided games). Moreover, this has implications for injury prevention, physical, psychological, and technical-tactical training since today’s soccer requires players to engage in repeated high-intensity actions, reach maximum speeds above 9 m/s, and develop technical-tactical coordination when running with the ball.

Key words

  • match analysis
  • tracking systems
  • external load
  • monitoring
  • European football
Open Access

Sensitivity of Field Tests for Assessment of Wrestlers Specific Fitness

Published Online: 08 Sep 2022
Page range: 267 - 276

Abstract

Abstract

The aim of this study was to determine the differences in performance, cardiac, and metabolic variables of combat-specific fitness of wrestlers from varying sports levels. The sample consisted of 61 active and highly trained adult wrestlers of national and international levels from Serbia, from both Greco-Roman and freestyle forms of wrestling, allocated into three groups: national team wrestlers (N = 15), first league competitive wrestlers (N = 20), and second league competitive wrestlers (N = 26). Participants performed two tests: a Specific Wrestling Fitness Test (SWFT) and a Specific Wrestling Performance Test (SWPT). Between-group differences were determined using multiple analysis of variance (MANOVA). Significant differences were obtained between wrestlers of different sports levels in TnThrows (F = 77.491, p < 0.001), SJFIndex (F = 49.710, p < 0.001), and SWPIndex (F = 31.205, p < 0.001) in the SWFT and in TnThrows (F = 71.051, p < 0.001), SJFIndex F = 45.343, p < 0.001), and SWPIndex (F = 26.820, p < 0.001) in the SWPT. Based on the results, it could be concluded that the SWFT and the SWPT provide very good sensitivity in the evaluation of the wrestlers specific fitness of wrestlers.

Key words

  • combat sports
  • wrestling
  • testing
  • discriminative
Open Access

Performance and Submaximal Adaptations to Additional Speed-Endurance Training vs. Continuous Moderate-Intensity Aerobic Training in Male Endurance Athletes

Published Online: 08 Sep 2022
Page range: 277 - 285

Abstract

Abstract

We examined performance and submaximal adaptations to additional treadmill-based speed-endurance training (SET) vs. continuous moderate-intensity aerobic training (MIT) twice / week. Twenty-two male endurance athletes were tested before and after 10-week SET (6-12 × 30-s sprints separated by 3-min rest intervals) and MIT (2040 min continuous running at ~70% maximal oxygen uptake [V̇O2max]). The SET group attained greater acute heart rate (HR) and blood lactate responses than the MIT group (d = 0.86–0.91). The SET group improved performance in a time-to-exhaustion trial, V̇O2max, and lactate threshold (d = 0.50–0.73), whereas no training-induced changes were observed in the MIT group. Additionally, the SET group reduced oxygen uptake, mean HR and improved running economy (d = 0.53–0.86) during running at 10 and 12 km·h-1. Additional SET imposes greater physiological demands than MIT resulting in superior performance adaptations and reduced energy cost in endurance athletes.

Key words

  • anaerobic training
  • maximal oxygen uptake
  • blood lactate
  • submaximal exercise
  • performance
Open Access

Better Offensive Strategy in Basketball: A Two-Point or a Three-Point Shot?

Published Online: 08 Sep 2022
Page range: 287 - 295

Abstract

Abstract

To better understand and explore the development trend of the offensive strategies of the world’s top basketball leagues, this study took NBA shooting data in the regular seasons from 2009/2010 to 2018/2019 as the samples and analysed the relationships between the shooting score ratio and game win probability, and the practical application of offensive strategies in games. The results showed that (1) increasing the number and the percentage of three-point offenses in the game can improve the probability of winning. However, too many two-point shots can affect the team’s winning probability to a certain extent. (2) The strong teams in the NBA focused more on the outside offense, while the weak teams focused more on the inside offense. (3) Statistical data further showed that whether a team’s opponent is strong or weak, taking the offensive strategy that tends toward the outside shot can lead to a higher game win probability than the offensive strategy that tends toward the inside offense.

Key words

  • basketball
  • NBA
  • offense strategy
  • outside offense
  • inside offense

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