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Informacje o czasopiśmie
Format
Czasopismo
eISSN
1899-7562
Pierwsze wydanie
13 Jan 2009
Częstotliwość wydawania
5 razy w roku
Języki
Angielski

Wyszukiwanie

Tom 74 (2020): Zeszyt 1 (August 2020)

Informacje o czasopiśmie
Format
Czasopismo
eISSN
1899-7562
Pierwsze wydanie
13 Jan 2009
Częstotliwość wydawania
5 razy w roku
Języki
Angielski

Wyszukiwanie

20 Artykułów

Resistance Training in Health and Sports Performance

Otwarty dostęp

Relationships between Isometric Strength and the 74.84-kg (165-lb) Body Drag Test in Law Enforcement Recruits

Data publikacji: 31 Aug 2020
Zakres stron: 5 - 13

Abstrakt

Abstract

This study investigated whether: law enforcement recruits could complete a 74.84-kg (165-lb) body drag without specific training; relationships between the body drag and absolute and relative isometric grip and leg/back strength could be established to assist with training recommendations; a strength baseline needed to complete the 74.84-kg body drag could be established. Retrospective analysis on a recruit class (72 males, 21 females) from one agency was conducted. Recruits completed the body drag, and had strength assessed by hand grip and leg/back dynamometers in the week before academy. The body drag required the recruit to lift the dummy to standing and drag it 9.75 m as quickly as possible. Independent samples t-tests calculated between-sex differences in the drag and strength measures. Recruits were ranked according to drag time to describe the strength of recruits that could not perform the task. Pearson’s correlations and a stepwise linear regression calculated relationships between the body drag and isometric strength. Male recruits completed the drag faster and were stronger than females (p < 0.001). Only two females could not complete the drag, and they had leg/back strength below 100 kg. Greater absolute (r = -0.599 and -0.677) and relative (r = -0.261 and -0.322) grip (combined score) and leg/back strength, respectively, related to a faster drag. Absolute leg/back strength predicted the body drag (r2 = 0.444). Improving absolute isometric grip and leg/back strength could enhance dragging ability. A minimum isometric leg/back strength score of 100 kg may be needed to perform a 74.84-kg body drag.

Key words

  • absolute strength
  • casualty drag
  • grip strength
  • leg/back dynamometer
  • police
  • tactical
  • victim drag
Otwarty dostęp

Kettlebell Training for Female Ballet Dancers: Effects on Lower Limb Power and Body Balance

Data publikacji: 31 Aug 2020
Zakres stron: 15 - 22

Abstrakt

Abstract

The aim of the present study was to evaluate the effects of 5 month kettlebell-based training on jumping performance, balance, blood pressure and heart rate in female classical ballet dancers. It was a clinical trial study with 23 female dancers (age = 21.74 ± 3.1 years; body height = 168.22 ± 5.12 cm; body mass = 53.69 ± 5.91 kg) took part in the study. Participants were divided into two groups: a kettlebell group (n = 13), that followed a commercial kettlebell training protocol named the “Simple & Sinister protocol”, and a traditional dance training control group (n = 10). In the kettlebell group, kettlebell training completely replaced the jump and balance section of dance classes. Both groups performed balance and jumping tests before and after the training period. Blood pressure and the heart rate were also measured. The kettlebell group showed significant improvements in the balance tests (antero-posterior and medio-lateral oscillation) with both legs and eyes open as well as in all types of jump exercises (unrotated: +39.13%, p < 0.005; with a turnout: +53.15%, p < 0.005), while maximum and minimum blood pressure and the heart rate decreased significantly (max: -7.90%, p < 0.05; min: -9.86%, p < 0.05; Heart rate: -17.07%, p < 0.01). The results for the control group were non-significant for any variable. Comparison between groups showed significant differences for all variables analyzed, with greater improvements for the kettlebell group. Our results suggest that specific kettlebell training could be effective in improving jump performance and balance in classical dancers to a significantly greater degree compared to classical dance training.

Key words

  • kettlebell
  • balance
  • ballet dancers
Otwarty dostęp

Methods for Regulating and Monitoring Resistance Training

Data publikacji: 31 Aug 2020
Zakres stron: 23 - 42

Abstrakt

Abstract

Individualisation can improve resistance training prescription. This is accomplished via monitoring or autoregulating training. Autoregulation adjusts variables at an individualised pace per performance, readiness, or recovery. Many autoregulation and monitoring methods exist; therefore, this review’s objective was to examine approaches intended to optimise adaptation. Up to July 2019, PubMed, Medline, SPORTDiscus, Scopus and CINAHL were searched. Only studies on methods of athlete monitoring useful for resistance-training regulation, or autoregulated training methods were included. Eleven monitoring and regulation themes emerged across 90 studies. Some physiological, performance, and perceptual measures correlated strongly (r ≥ 0.68) with resistance training performance. Testosterone, cortisol, catecholamines, cell-free DNA, jump height, throwing distance, barbell velocity, isometric and dynamic peak force, maximal voluntary isometric contractions, and sessional, repetitions in reserve-(RIR) based, and post-set Borg-scale ratings of perceived exertion (RPE) were strongly associated with training performance, respectively. Despite strong correlations, many physiological and performance methods are logistically restrictive or limited to lab-settings, such as blood markers, electromyography or kinetic measurements. Some practical performance tests such as jump height or throw distance may be useful, low-risk stand-ins for maximal strength tests. Performance-based individualisation of load progression, flexible training configurations, and intensity and volume modifications based on velocity and RIR-based RPE scores are practical, reliable and show preliminary utility for enhancing performance.

Key words

  • autoregulation
  • strength
  • rating of perceived exertion (RPE)
  • repetitions in reserve (RIR)
  • velocity
Otwarty dostęp

Effects of Short-Term Core Stability Training on Dynamic Balance and Trunk Muscle Endurance in Novice Olympic Weightlifters

Data publikacji: 31 Aug 2020
Zakres stron: 43 - 50

Abstrakt

Abstract

Our primary objective was to investigate the effects of short-term core stability training on dynamic balance and trunk muscle endurance in novice weightlifters learning the technique of the Olympic lifts. Our secondary objective was to compare dynamic balance and trunk muscle endurance between novice and experienced weightlifters. Thirty novice (NOV) and five experienced (EXP) weightlifters participated in the study. Mediolateral (ML) and anteroposterior (AP) dynamic balance and trunk muscle endurance testing were performed a week before (Pre) and after (Post) a 4-week core stability training program. In the NOV group, there was an improvement of both dynamic balance (ML and AP, p = 0.0002) and trunk muscle endurance (p = 0.0002). In the EXP group, there was no significant difference between Pre and Post testing conditions, except an increase in muscle endurance in the right-side plank (p = 0.0486). Analysis of the results showed that experienced lifters were characterized by more effective dynamic balance and greater core muscle endurance than their novice peers, not only before the training program but after its completion as well. In conclusion, the applied short-term core stability training improved dynamic balance and trunk muscle endurance in novice weightlifters learning the Olympic lifts. Such an exercise program can be incorporated into a training regime of novice weightlifters to prepare them for technically difficult tasks of the Olympic snatch and clean and jerk.

Key words

  • resistance training
  • lifting technique
  • body balance
  • balance board
Otwarty dostęp

The Effects of Low-Load vs. High-Load Resistance Training on Muscle Fiber Hypertrophy: A Meta-Analysis

Data publikacji: 31 Aug 2020
Zakres stron: 51 - 58

Abstrakt

Abstract

The aim of this meta-analysis was to explore the effects of low-load vs. high-load resistance training on type I and type II muscle fiber hypertrophy. Searches for studies were performed through ten databases. Studies were included if they: (a) compared the effects of low-load vs. high-load resistance training (performed to momentary muscular failure); and, (b) assessed muscle fiber hypertrophy. A random-effects meta-analysis was performed to analyze the data. Ten study groups were included in the analysis. In the meta-analysis for the effects of low-load vs. high-load resistance training on type I muscle fiber hypertrophy, there was no significant difference between the training conditions (standardized mean difference: 0.28; 95% confidence interval: –0.27, 0.82; p = 0.316; I2 = 18%; 95% prediction interval: –0.71, 1.28). In the meta-analysis for the effects of low-load vs. high-load resistance training on type II muscle fiber hypertrophy, there was no significant difference between the training conditions (standardized mean difference: 0.30; 95% confidence interval: –0.05, 0.66; p = 0.089; I2 = 0%; 95% prediction interval: –0.28, 0.88). In this meta-analysis, there were no significant differences between low-load and high-load resistance training on hypertrophy of type I or type II muscle fibers. The 95% confidence and prediction intervals were very wide, suggesting that the true effect in the population and the effect reported in a future study conducted on this topic could be in different directions and anywhere from trivial to very large. Therefore, there is a clear need for future research on this topic.

Key words

  • loading zones
  • intensity
  • volume
  • cross-sectional area
  • CSA
Otwarty dostęp

Dynamic Strength Index: Relationships with Common Performance Variables and Contextualization of Training Recommendations

Data publikacji: 31 Aug 2020
Zakres stron: 59 - 70

Abstrakt

Abstract

The purposes of this study were to examine the relationships between dynamic strength index (DSI) and other strength-power performance characteristics and to contextualize DSI scores using case study comparisons. 88 male and 67 female NCAA division I collegiate athletes performed countermovement jumps (CMJ) and isometric mid-thigh pulls (IMTP) during a pre-season testing session as part of a long-term athlete monitoring program. Spearman’s correlations were used to assess the relationships between DSI and CMJ peak force, height, modified reactive strength index, peak power and IMTP peak force and rate of force development (RFD). Very large relationships existed between DSI and IMTP peak force (r = -0.848 and -0.746), while small-moderate relationships existed between DSI and CMJ peak force (r = 0.297 and 0.313), height (r = 0.108 and 0.167), modified reactive strength index (r = 0.174 and 0.274), and IMTP RFD (r = -0.341 and -0.338) for men and women, respectively. Finally, relationships between DSI and CMJ peak power were trivial-small for male (r = 0.008) and female athletes (r = 0.191). Case study analyses revealed that despite similar DSI scores, each athlete’s percentile rankings for each variable and CMJ force-time characteristics were unique, which may suggest different training emphases are needed. Based on the explained variance, an athlete’s IMTP performance may have a larger influence on their DSI score compared to the CMJ. DSI scores should be contextualized using additional performance data to ensure each individual athlete receives the appropriate training stimulus during different training phases throughout the year.

Key words

  • countermovement jump
  • isometric mid-thigh pull, strength
  • peak power
  • rate of force development
  • reactive strength index-modified
Otwarty dostęp

In-Season Strength Training in Elite Junior Swimmers: The Role of the Low-Volume, High-Velocity Training on Swimming Performance

Data publikacji: 31 Aug 2020
Zakres stron: 71 - 84

Abstrakt

Abstract

The aim of this study was to analyze the effect of long-term combined strength training (ST) and plyometrics on strength, power and swimming performances in elite junior swimmers during a competitive season. Ten elite junior swimmers (5 women and 5 men) completed the study (age: 16.6 ± 0.7 years; mass: 62.2 ± 5.4 kg; stature: 1.70 ± 0.07 m). The participants trained twice a week during 20 weeks. The ST program consisted of upper- and lower limbs exercises with low loads and low volume, lifting the load at maximal intended velocity. The effect of the training protocol was assessed using the 1RM in the full squat (SQ) and bench press (BP), jump height (CMJ), the maximal number of repetitions completed in the pull-up (PU) exercise and time during 50-m freestyle. Training program resulted in significant improvements in CMJ (12.1%, ES: 0.57), maximal dynamic strength in the SQ (16.4%, ES: 0.46) and BP (12.1%, ES: 0.34) exercises, the maximum number of repetitions completed during the PU test (90.7%, ES: 0.57) and swimming performance (-3.9%, ES: 0.45). There were no significant differences between both genders. The relative changes in swimming performance showed significant relationship with the relative changes in 1RM of SQ for pooled data (r=-0.66, p<0.05) and the relative changes in the PU exercise in female swimmers (r=-0.99, p<0.05). Therefore, coaches and strength and conditioning professionals should consider including in-season dry-land ST programs within the training routine in order to obtain further improvements in swimming performance.

Key words

  • resistance training
  • swim time
  • vertical jump
  • full squat
  • youth swimmers
Otwarty dostęp

Does Acute Blood Flow Restriction with Pneumatic and Non-Pneumatic Non-Elastic Cuffs Promote Similar Responses in Blood Lactate, Growth Hormone, and Peptide Hormone?

Data publikacji: 31 Aug 2020
Zakres stron: 85 - 97

Abstrakt

Abstract

Blood flow restriction (BFR) can be used during resistance training (RT) through pressure application with pneumatic (pressurized) cuffs (PC) or non-pneumatic (practical) cuffs (NPC). However, PC are expensive and difficult to use in the gym environment compared to NPC. The main aim was to compare, correlate, and verify the hormonal and metabolic responses between PC and NPC during a low-load BFR during RT of the upper-body. The secondary aim was to compare blood lactate (BLa) concentration between pre- and post-exercise (2-min into recovery), as well as growth hormone (GH) and insulin-like growth factor 1 (IGF-1) concentration before, 10-min, and 15-min post exercise. Sixteen trained men randomly and alternately completed two experimental RT protocols of the upper-body : A) RT with BFR at 20% 1RM using PC (RT-BFR-PC) and (B) RT with BFR at 20% 1RM using NPC (RT-BFR-NPC) in the bench press, wide-grip lat pulldown, shoulder press, triceps pushdown, and biceps curl exercises. There was no significant difference in BLa 2-min post exercise (p=0.524), GH 10-min (p=0.843) and 15-min post exercise (p=0.672), and IGF-1 10-min (p=0.298) and 15-min post exercise (p=0.201) between RT-BFR-PC and RT-BFR-NPC. In addition, there was a moderate correlation, satisfactory ICCs, and agreement between both protocols in metabolic and hormonal responses. The experimental sessions promoted significant increases in GH and BLa, but not in IGF-1 (p<0.05). The absence of a significant difference between RT-BFR-PC and RT-BFR-NPC in metabolic and hormonal responses highlight the applicability of NPC as a low-cost and easy-to-use tool for BFR upper-body RT.

Key words

  • katsu training
  • resistance exercise
  • GH
  • lactate
  • IGF-1
Otwarty dostęp

The Effects of Plyometric Conditioning on Post-Activation Bench Press Performance

Data publikacji: 31 Aug 2020
Zakres stron: 99 - 108

Abstrakt

Abstract

The present study aimed to determine the effects of plyometric push-ups as a conditioning activity (CA) on high-loaded bench press performance. Two groups of resistance-trained males age (24.5 ± 2.6 years, body mass 84.8 ± 8 kg) performed one of two CA protocols: 3 sets of 5 repetitions of plyometric push-ups with a 1 min rest interval between sets (PAPE; n=12) or equal time aerobic warm-up (CONT; n=12). Four minutes after completion of the CA protocols the participants performed 3 sets of 3 repetitions of the bench press exercise at 70%1RM and 4 min rest interval between sets to assess post-activation differences in peak power output (PP), mean power output (MP), peak bar velocity (PV), and mean bar velocity (MV) between conditions. The two-way ANOVA revealed significant condition × set interaction effect for PP (p<0.01), MP (p<0.05), PV (p<0.01), and MV (p=0.02). The post hoc for condition × set interaction showed that PAPE caused a significant decrease in PP and PV for P-Set2 and P-Set3 when compared to baseline (BA). The MP and MV for the PAPE condition decreased significantly during the P-Set3 compared to BA and to P-Set1. The t-test comparisons for delta values showed significant differences between PAPE and CONT in PP for P-Set1 – BA (p<0.01), in MP for P-Set2 – P-Set1 (p<0.03) and for P-Set3 – P-Set1 (p=0.04). Furthermore, there were significant differences in PV for P-Set3 – BA; P-Set2 – P-Set1; P-Set3 – P-Set1 (p<0.01; p<0.01; p<0.02 respectively). Finally, there were significant differences in MV for P-Set1 – BA; P-Set2 – P-Set1 and P-Set3 – P-Set1 (p<0.01; p<0.01; p<0.02 respectively). This study demonstrated that plyometric push-ups lead to performance enhancement of the bench press exercise at 70%1RM. The increases in performance were observed only in the first set following the CA, while a significant decrease of these variables was registered in P-Set2 and P-Set3.

Key words

  • push-up
  • PAPE
  • complex training
  • sport performance
  • resistance training
Otwarty dostęp

Influence of the Strap Rewind Height During a Conical Pulley Exercise

Data publikacji: 31 Aug 2020
Zakres stron: 109 - 118

Abstrakt

Abstract

The use of flywheel devices has increased in popularity within resistance training programs. However, little is known about modifiable variables which may affect power output responses, as the rope length and the height level used in a conical pulley device. The aim of this study was to assess the influence of using three different rope lengths (1.5, 2.5 and 3.5 meters) and four different height levels (L1, L2, L3 and L4) on concentric peak power (PPconc), eccentric peak power (PPecc) and eccentric overload (eccentric/concentric PP ratio; EO) during conical pulley exercises (i.e. seated and stand-up row). A total of 29 recreationally trained subjects (25.3±7.1 years; 1.74±0.06 m; 72.5±8.3 kg) took part in the study. Testing sessions consisted of 1 set of 10 repetitions under each condition; experiment 1: seated row exercise using the three different rope lengths; experiment 2: stand-up row exercise using four different height levels of the conical pulley. Results from experiment 1 did not show differences between rope lengths, although a trend for greater PPecc (ES=0.36-0.38) and EO (ES=0.40-0.41) was found when using longer rope lengths (2.5 and 3.5). Experiment 2 showed significant increases in both PPconc and PPecc as the height level used was closer to the cone base (L4). In contrast, EO values were significantly greater when using upper height levels (L1). These results suggest that the height level used during conical pulley exercises highly influences power output responses. Therefore, this variable should be carefully managed depending on the training goal (e.g. power vs hypertrophy).

Key words

  • eccentric overload
  • strength
  • power output
  • flywheel
Otwarty dostęp

Gender and Age Related Differences in Leg Stiffness and Reactive Strength in Adolescent Team Sports Players

Data publikacji: 31 Aug 2020
Zakres stron: 119 - 129

Abstrakt

Abstract

The aim of the present study was to identify potential gender differences in leg stiffness and reactive strength during hopping tasks in 13 to16-year old team sports players. Reactive strength index (RSI) and leg stiffness were obtained in two consecutive seasons from 51 girls (U14: n = 31, U16: n = 20) and 65 boys (U14: n = 32, U16: n = 33). A significant main effect on absolute (U14: p = 0.022, η2= 0.084; U16: p < 0.001, η2= 0.224) and relative leg stiffness (U14 p<0.001; η2= 0.195; U16; p = 0.008, η2= 0.128) for gender was found in both groups with values higher in boys than in girls. For absolute and relative stiffness gender differences in the U14 group were significant in the 1st year only (p=0.027 and p=0.001), and for the U16s in the 2nd year only (p < 0.001 and p = 0.022). For RSI, a significant main effect for gender was observed in the U16 group only (p < 0.001 η2= 0.429) with values significantly higher in boys than in girls in both years of measurement (p = 0.001; p < 0.001). Results of this study support previous limited findings, mostly related to non-athletes, suggesting lower stretch-shortening cycle capability in adolescence female compared to male, however our data only partly supports the theory that quality of neuromuscular functions increases with age until post puberty.

Key words

  • youth
  • neuromuscular
  • stretch-shortening cycle
  • reactive strength index
Otwarty dostęp

Comparison of Muscle Activation and Kinematics in 6-RM Squatting With Low and High Barbell Placement

Data publikacji: 31 Aug 2020
Zakres stron: 131 - 142

Abstrakt

Abstract

The aim of this study was to compare 6-RM muscle activation and kinematics in back squats with low and high barbell placements. Twelve resistance-trained males (23.5 ± 2.6 years, 86.8 ± 21.3 kg, 1.81 ± 0.08 m) with a minimum of 2 years of squatting experience performed a 6-RM using high and low barbell placements while muscle activation of eight muscles and joint kinematics were measured. During high barbell placement squats, lifting time was longer, with lower average velocity than low barbell placement. This was accompanied by a lesser knee flexion angle at the lowest point of the squat, and larger hip flexion angles during high, compared to low barbell squats. Furthermore, peak angular ankle, knee and hip velocities in the descending phase developed differently between conditions. No significant differences in muscle activation were found between conditions. Thus, our data suggests gross muscular adaptations between barbell placements may be similar over time, and therefore, from a muscular development standpoint, both squat styles are valid. Furthermore, unlike the low barbell placement, fatigue may manifest earlier itself in the high barbell squats during 6-RMs as sets progress toward a lifter’s maximal capacity, altering kinematics, especially in the last repetition.

Key words

  • EMG
  • resistance exercise
  • performance
Otwarty dostęp

Genetics of Muscle Stiffness, Muscle Elasticity and Explosive Strength

Data publikacji: 31 Aug 2020
Zakres stron: 143 - 159

Abstrakt

Abstract

Muscle stiffness, muscle elasticity and explosive strength are the main components of athletes’ performance and they show a sex-based as well as ethnicity variation. Muscle stiffness is thought to be one of the risk factors associated with sports injuries and is less common in females than in males. These observations may be explained by circulating levels of sex hormones and their specific receptors. It has been shown that higher levels of estrogen are associated with lower muscle stiffness responsible for suppression of collagen synthesis. It is thought that these properties, at least in part, depend on genetic factors. Particularly, the gene encoding estrogen receptor 1 (ESR1) is one of the candidates that may be associated with muscle stiffness. Muscle elasticity increases with aging and there is evidence suggesting that titin (encoded by the TTN gene), a protein that is expressed in cardiac and skeletal muscles, is one of the factors responsible for elastic properties of the muscles. Mutations in the TTN gene result in some types of muscular dystrophy or cardiomyopathy. In this context, TTN may be regarded as a promising candidate for studying the elastic properties of muscles in athletes. The physiological background of explosive strength depends not only on the muscle architecture and muscle fiber composition, but also on the central nervous system and functionality of neuromuscular units. These properties are, at least partly, genetically determined. In this context, the ACTN3 gene code for α-actinin 3 has been widely researched.

Key words

  • sports genetics
  • genetic markers
  • genetic polymorphism
  • muscle rigidness
  • power
Otwarty dostęp

Unilateral Plyometric Training is Superior to Volume-Matched Bilateral Training for Improving Strength, Speed and Power of Lower Limbs in Preadolescent Soccer Athletes

Data publikacji: 31 Aug 2020
Zakres stron: 161 - 176

Abstrakt

Abstract

This study compared the effects of unilateral and bilateral plyometric training on strength, sprint performance and lower limb power. Sixty-eight preadolescent soccer athletes were randomly assigned to a unilateral plyometric training group (n=23), a bilateral plyometric training group (n=23) and a control group (n=22). Both plyometric training groups trained with equal volumes of unilateral or bilateral exercises for 15 minutes in each session, at which time the control group performed soccer-specific drills. Plyometric exercises were executed twice weekly for 10 weeks during the competitive season. The following tests were performed before and after the intervention: single-leg and double-leg countermovement jump, squat jump, horizontal jumps in different directions, maximal isometric strength of quadriceps and hamstrings, sprint performance, agility and balance. Unilateral plyometric training resulted in greater improvements compared to the control group in the following variables: hamstrings strength (ES: 0.91, p=0.037), 5m sprint time (ES: 0.93, p=0.004), single-leg countermovement jump (ES: 0.90, p=0.006), single- and double-leg squat jump (ES: 0.87, p=0.030 and ES: 0.73, p=0.067, respectively) and single-leg hop performance (ES: 1.01, p=0.004). The only tests where there was an improvement of BPT compared with the CG were the single-leg and double leg SJ (ES: 0.76, p=0.026; ES: 0.70, p=0.050). Quadriceps strength, side hop test, double-leg horizontal jump test, flamingo balance test and modified agility T-test were equally improved in all three groups (p<0.001). In conclusion, unilateral lower-limb plyometric training is more effective in increasing muscle strength and power in preadolescent soccer players when compared to bilateral training or soccer training alone.

Key words

  • single-leg training
  • stretch-shortening cycle
  • performance
  • youth athletes
Otwarty dostęp

Caffeine Ingestion Enhances Repetition Velocity in Resistance Exercise: A Randomized, Crossover, Double-Blind Study Involving Control and Placebo Conditions

Data publikacji: 31 Aug 2020
Zakres stron: 177 - 183

Abstrakt

Abstract

We aimed to examine the effects of placebo and caffeine compared to a control condition on mean velocity in the bench press exercise. Twenty-five resistance-trained men participated in this randomized, crossover, double-blind study. The participants performed the bench press with loads of 50%, 75%, and 90% of one-repetition maximum (1RM), after no supplementation (i.e., control), and after ingesting caffeine (6 mg/kg), and placebo (6 mg/kg of dextrose). At 50% 1RM, there was a significant effect of caffeine on mean velocity compared to control (effect size [ES] = 0.29; p = 0.003), but not when compared to placebo (ES = 0.09; p = 0.478). At 75% 1RM, there was a significant effect of caffeine on mean velocity compared to placebo (ES = 0.34; p = 0.001), and compared to control (ES = 0.32; p < 0.001). At 90% 1RM, there was a significant effect of caffeine on mean velocity compared to placebo (ES = 0.36; p < 0.001), and compared to control (ES = 0.46; p < 0.001). There was no significant difference between placebo and control in any of the analyzed outcomes. When evaluated pre-exercise and post-exercise, 20% to 44% and 28% to 52% of all participants identified caffeine and placebo trials beyond random chance, respectively. Given that the blinding of the participants was generally effective, and that there were no significant ergogenic effects of placebo ingestion, the improvements in performance following caffeine ingestion can be mainly attributed to caffeine’s physiological mechanisms of action.

Słowa kluczowe

  • ergogenic aid
  • supplements
  • mean repetition velocity
Otwarty dostęp

Caffeine Increases Muscle Performance During a Bench Press Training Session

Data publikacji: 31 Aug 2020
Zakres stron: 185 - 193

Abstrakt

Abstract

Previous investigations have established the ergogenic effect of caffeine on maximal muscle strength, power output and strength-endurance. However, these investigations used testing protocols that do not replicate the structure of a regular strength training session. Thus, the aim of this study was to investigate the effect of acute caffeine ingestion on muscle performance during a simulated velocity-based training workout. In a double-blind, randomized and counterbalanced experiment, 12 participants performed two experimental trials after ingesting 3 mg/kg/b.m. of caffeine or a placebo. The trials consisted of 4 sets of 8 repetitions of the bench press exercise at 70% of their one-repetition maximum performed at maximal velocity. Bar velocity was recorded with a rotatory encoder and force, power output and work were calculated. Regarding the whole workout, caffeine increased mean bar velocity (+7.8%; p=0.002), peak bar velocity (+8.7%; p=0.006), mean force (+1.5%; p=0.002), mean power output (+10.1%; p=0.003) and peak power output (+8.2%; p=0.004) when compared to the placebo. The total work performed in the caffeine trial was superior to the placebo trial (7.01±2.36 vs 6.55±2.20 kJ, p=0.001). These results suggest that the acute intake of 3 mg/kg/b.m. of caffeine before a velocity-based strength workout increased muscle performance and the total work performed across the whole training session. Thus, caffeine can be considered as an effective strategy to enhance muscle performance during the bench press training sessions.

Key words

  • resistance exercise
  • muscle strength
  • strength training
  • exercise
  • ergogenic aid
Otwarty dostęp

Transfer of Dry-Land Resistance Training Modalities to Swimming Performance

Data publikacji: 31 Aug 2020
Zakres stron: 195 - 203

Abstrakt

Abstract

A great number of studies focusing on the effects of dry-land resistance training interventions on swimming performance remain inconclusive. It is suggested that transferability of dry-land strength gains to swimming performance appear when dry-land resistance training programs are swim-specific. The main aim of this study was to compare the effects of specific dry-land resistance training on an ergometer with traditional dry-land exercises, and to determine how much of the resistance training effects were transferred to specific swimming conditions. The study included a group of 26 youth competitive male swimmers (age 15.7 ± 0.5 years, height 174.6 ± 6.6 cm, weight 68.4 ± 8.2 kg, training experience 5.8±0.7 years) of regional level. They were randomly allocated to one of two groups: experimental (E) and control (T). Both groups were involved in a 12-week dry-land resistance training concentrated on increasing muscular strength and power output of the upper limbs. Group E used a specialized ergometer (JBA – Zbigniew Staniak), while group T performed traditional resistance exercises. The program consisted of 10 sets of 30 s of exercise with 30 s rest intervals between each set. A two-way repeated measures ANOVA with Tukey HSD post hoc comparisons was used to determine if any significant differences existed between training groups across pretest and posttest conditions. The significance level was set at p ≤ 0.05. Dry-land resistance training modalities were the only differences in training between both groups. Our findings show that rates of transfer are much higher in group E than in group T, which resulted in a significant increase in swimming velocity (by 4.32%, p<0.001; ES=1.23, and 2.78%, p<0.003, ES=0.31, respectively).

Key words

  • swimmers
  • front crawl
  • strength
  • power output
  • ergometer
Otwarty dostęp

Impact of Rest-Redistribution on Fatigue During Maximal Eccentric Knee Extensions

Data publikacji: 31 Aug 2020
Zakres stron: 205 - 214

Abstrakt

Abstract

Redistributing long inter-set rest intervals into shorter but more frequent rest intervals generally maintains concentric performance, possibly due to improved energy store maintenance. However, eccentric actions require less energy than concentric actions, meaning that shorter but more frequent sets may not affect eccentric actions to the same degree as concentric actions. Considering the increased popularity of eccentric exercise, the current study evaluated the effects of redistributing long inter-set rest periods into shorter but more frequent rest periods during eccentric only knee extensions. Eleven resistance-trained men performed 40 isokinetic unilateral knee extensions at 60°·s−1 with 285 s of total rest using traditional sets (TS; 4 sets of 10 with 95 s inter-set rest) and rest-redistribution (RR; 20 sets of 2 with 15 s inter-set rest). Before and during exercise, muscle oxygenation was measured via near-infrared spectroscopy, and rating of perceived exertion (RPE) was recorded after every 10th repetition. There were no differences between protocols for peak torque (RR, 241.58±47.20 N; TS, 231.64±48.87 N; p=0.396) or total work (RR, 215.26±41.47 J; TS, 209.71±36.02 J; p=0.601), but moderate to large effect sizes existed in later repetitions (6,8,10) with greater peak torque during RR (d=0.66-1.19). For the entire session, RR had moderate effects on RPE (RR, 5.73±1.42; TS, 6.09±1.30; p=0.307; d=0.53) and large effects on oxygen saturation (RR, 5857.4±310.0; TS, 6495.8±273.8; p=0.002, d=2.13). Therefore, RR may maintain peak torque or total work during eccentric exercise, improve oxygen utilization at the muscle, and reduce the perceived effort.

Key words

  • muscle oxygenation
  • velocity
  • fatigue
  • resistance training
  • isokinetic
  • cluster sets
Otwarty dostęp

Effects of Different Inertial Load Settings on Power Output Using a Flywheel Leg Curl Exercise and its Inter-Session Reliability

Data publikacji: 31 Aug 2020
Zakres stron: 215 - 226

Abstrakt

Abstract

This study aimed to analyze the influence of the inertial load on both concentric and eccentric power output production during the flywheel leg curl exercise, and to assess the reliability of power output variables. Sixteen participants (8 males, 8 females) attended 4 testing sessions. During testing, participants performed one set of eight repetitions using a specific inertial load (0.083, 0.132, 0.182, 0.266 and 0.350 kg·m2) with a flywheel leg curl exercise. Concentric (CON) power, eccentric (ECC) power and the ECC/CON ratio were analyzed. The reliability analysis between sessions was performed. A significant interaction of inertia load x gender was found in CON power (p < 0.001) and in ECC power (p = 0.004), but not in the ECC/CON ratio (p = 0.731). A significant with-in (inertia loads) effect was found in CON power (p < 0.001) and in ECC power (p < 0.001), but not in the ECC/CON ratio (p = 0.096). CON power showed very high reliability scores, ECC power showed high to very high reliability scores, while the ECC/CON ratio ranged from poor to moderate. A significant between gender effect was found in CON power (p < 0.001) and in ECC power (p < 0.001), but not in the ECC/CON ratio (p = 0.752). This study is the first to report that power output in the flywheel leg curl exercise is altered by the inertia load used, as well as power output is different according to gender. CON and ECC power output presents high to very high reliability scores, and the ECC/CON ratio should not be used instead. These results can have important practical implications for testing and training prescription in sports.

Key words

  • eccentric overload
  • iso-inertial
  • resistance training
  • hamstring muscles
Otwarty dostęp

Resistance Exercise Intensity Does Not Influence Neurotrophic Factors Response in Equated Volume Schemes

Data publikacji: 31 Aug 2020
Zakres stron: 227 - 236

Abstrakt

Abstract

The aim of the present study was to evaluate the effects of 2 different intensities of resistance training (RT) bouts, performed with the equated total load lifted (TLL), on the acute responses of neurotrophic factors (NFs) (brain-derived neurotrophic factor [BDNF]; and nerve growth factor [NGF]), as well as on metabolic (lactate concentration) and hormonal (salivary cortisol concentration) responses. Thirty participants (males, 22.8 ± 2.3 years old, 177 ± 6.8 cm, 75.5 ± 7.9 kg, n = 15; and females, 22.2 ± 1.7 years, 163.7 ± 6.5 cm, 57 ± 7.6 kg, n = 15) performed 2 separate acute RT bouts with one week between trials. One bout consisted of 4 sets of 5 submaximal repetitions at 70% of 1RM and the other of 4 sets of 10 submaximal repetitions at 35% of 1RM for each exercise. Both RT bouts were conducted using the bench press and squat exercises. The TLL in each bout (determined by sets x repetitions x load [kg]) was equated. Serum BDNF, serum NGF, salivary cortisol, and blood lactate concentration were determined pre- and post-RT. No significant pre- to post-exercise increase in neurotrophic factors (p > 0.05; BDNF; effect size = 0.46 and NGF; effect size = 0.48) was observed for either of the RT bouts. A similar increase in blood lactate concentration was observed pre- to post-exercise for both RT bouts (p < 0.05). Cortisol increased similarly for both RT bouts, when compared to the resting day condition (p < 0.05). In conclusion, the results suggest that, despite differences in RT schemes, a similar acute neurotrophic, metabolic and hormonal response was observed when the TLL is equated.

Key words

  • BDNF
  • NGF
  • Cortisol
  • Blood Lactate
  • Resistance Training
20 Artykułów

Resistance Training in Health and Sports Performance

Otwarty dostęp

Relationships between Isometric Strength and the 74.84-kg (165-lb) Body Drag Test in Law Enforcement Recruits

Data publikacji: 31 Aug 2020
Zakres stron: 5 - 13

Abstrakt

Abstract

This study investigated whether: law enforcement recruits could complete a 74.84-kg (165-lb) body drag without specific training; relationships between the body drag and absolute and relative isometric grip and leg/back strength could be established to assist with training recommendations; a strength baseline needed to complete the 74.84-kg body drag could be established. Retrospective analysis on a recruit class (72 males, 21 females) from one agency was conducted. Recruits completed the body drag, and had strength assessed by hand grip and leg/back dynamometers in the week before academy. The body drag required the recruit to lift the dummy to standing and drag it 9.75 m as quickly as possible. Independent samples t-tests calculated between-sex differences in the drag and strength measures. Recruits were ranked according to drag time to describe the strength of recruits that could not perform the task. Pearson’s correlations and a stepwise linear regression calculated relationships between the body drag and isometric strength. Male recruits completed the drag faster and were stronger than females (p < 0.001). Only two females could not complete the drag, and they had leg/back strength below 100 kg. Greater absolute (r = -0.599 and -0.677) and relative (r = -0.261 and -0.322) grip (combined score) and leg/back strength, respectively, related to a faster drag. Absolute leg/back strength predicted the body drag (r2 = 0.444). Improving absolute isometric grip and leg/back strength could enhance dragging ability. A minimum isometric leg/back strength score of 100 kg may be needed to perform a 74.84-kg body drag.

Key words

  • absolute strength
  • casualty drag
  • grip strength
  • leg/back dynamometer
  • police
  • tactical
  • victim drag
Otwarty dostęp

Kettlebell Training for Female Ballet Dancers: Effects on Lower Limb Power and Body Balance

Data publikacji: 31 Aug 2020
Zakres stron: 15 - 22

Abstrakt

Abstract

The aim of the present study was to evaluate the effects of 5 month kettlebell-based training on jumping performance, balance, blood pressure and heart rate in female classical ballet dancers. It was a clinical trial study with 23 female dancers (age = 21.74 ± 3.1 years; body height = 168.22 ± 5.12 cm; body mass = 53.69 ± 5.91 kg) took part in the study. Participants were divided into two groups: a kettlebell group (n = 13), that followed a commercial kettlebell training protocol named the “Simple & Sinister protocol”, and a traditional dance training control group (n = 10). In the kettlebell group, kettlebell training completely replaced the jump and balance section of dance classes. Both groups performed balance and jumping tests before and after the training period. Blood pressure and the heart rate were also measured. The kettlebell group showed significant improvements in the balance tests (antero-posterior and medio-lateral oscillation) with both legs and eyes open as well as in all types of jump exercises (unrotated: +39.13%, p < 0.005; with a turnout: +53.15%, p < 0.005), while maximum and minimum blood pressure and the heart rate decreased significantly (max: -7.90%, p < 0.05; min: -9.86%, p < 0.05; Heart rate: -17.07%, p < 0.01). The results for the control group were non-significant for any variable. Comparison between groups showed significant differences for all variables analyzed, with greater improvements for the kettlebell group. Our results suggest that specific kettlebell training could be effective in improving jump performance and balance in classical dancers to a significantly greater degree compared to classical dance training.

Key words

  • kettlebell
  • balance
  • ballet dancers
Otwarty dostęp

Methods for Regulating and Monitoring Resistance Training

Data publikacji: 31 Aug 2020
Zakres stron: 23 - 42

Abstrakt

Abstract

Individualisation can improve resistance training prescription. This is accomplished via monitoring or autoregulating training. Autoregulation adjusts variables at an individualised pace per performance, readiness, or recovery. Many autoregulation and monitoring methods exist; therefore, this review’s objective was to examine approaches intended to optimise adaptation. Up to July 2019, PubMed, Medline, SPORTDiscus, Scopus and CINAHL were searched. Only studies on methods of athlete monitoring useful for resistance-training regulation, or autoregulated training methods were included. Eleven monitoring and regulation themes emerged across 90 studies. Some physiological, performance, and perceptual measures correlated strongly (r ≥ 0.68) with resistance training performance. Testosterone, cortisol, catecholamines, cell-free DNA, jump height, throwing distance, barbell velocity, isometric and dynamic peak force, maximal voluntary isometric contractions, and sessional, repetitions in reserve-(RIR) based, and post-set Borg-scale ratings of perceived exertion (RPE) were strongly associated with training performance, respectively. Despite strong correlations, many physiological and performance methods are logistically restrictive or limited to lab-settings, such as blood markers, electromyography or kinetic measurements. Some practical performance tests such as jump height or throw distance may be useful, low-risk stand-ins for maximal strength tests. Performance-based individualisation of load progression, flexible training configurations, and intensity and volume modifications based on velocity and RIR-based RPE scores are practical, reliable and show preliminary utility for enhancing performance.

Key words

  • autoregulation
  • strength
  • rating of perceived exertion (RPE)
  • repetitions in reserve (RIR)
  • velocity
Otwarty dostęp

Effects of Short-Term Core Stability Training on Dynamic Balance and Trunk Muscle Endurance in Novice Olympic Weightlifters

Data publikacji: 31 Aug 2020
Zakres stron: 43 - 50

Abstrakt

Abstract

Our primary objective was to investigate the effects of short-term core stability training on dynamic balance and trunk muscle endurance in novice weightlifters learning the technique of the Olympic lifts. Our secondary objective was to compare dynamic balance and trunk muscle endurance between novice and experienced weightlifters. Thirty novice (NOV) and five experienced (EXP) weightlifters participated in the study. Mediolateral (ML) and anteroposterior (AP) dynamic balance and trunk muscle endurance testing were performed a week before (Pre) and after (Post) a 4-week core stability training program. In the NOV group, there was an improvement of both dynamic balance (ML and AP, p = 0.0002) and trunk muscle endurance (p = 0.0002). In the EXP group, there was no significant difference between Pre and Post testing conditions, except an increase in muscle endurance in the right-side plank (p = 0.0486). Analysis of the results showed that experienced lifters were characterized by more effective dynamic balance and greater core muscle endurance than their novice peers, not only before the training program but after its completion as well. In conclusion, the applied short-term core stability training improved dynamic balance and trunk muscle endurance in novice weightlifters learning the Olympic lifts. Such an exercise program can be incorporated into a training regime of novice weightlifters to prepare them for technically difficult tasks of the Olympic snatch and clean and jerk.

Key words

  • resistance training
  • lifting technique
  • body balance
  • balance board
Otwarty dostęp

The Effects of Low-Load vs. High-Load Resistance Training on Muscle Fiber Hypertrophy: A Meta-Analysis

Data publikacji: 31 Aug 2020
Zakres stron: 51 - 58

Abstrakt

Abstract

The aim of this meta-analysis was to explore the effects of low-load vs. high-load resistance training on type I and type II muscle fiber hypertrophy. Searches for studies were performed through ten databases. Studies were included if they: (a) compared the effects of low-load vs. high-load resistance training (performed to momentary muscular failure); and, (b) assessed muscle fiber hypertrophy. A random-effects meta-analysis was performed to analyze the data. Ten study groups were included in the analysis. In the meta-analysis for the effects of low-load vs. high-load resistance training on type I muscle fiber hypertrophy, there was no significant difference between the training conditions (standardized mean difference: 0.28; 95% confidence interval: –0.27, 0.82; p = 0.316; I2 = 18%; 95% prediction interval: –0.71, 1.28). In the meta-analysis for the effects of low-load vs. high-load resistance training on type II muscle fiber hypertrophy, there was no significant difference between the training conditions (standardized mean difference: 0.30; 95% confidence interval: –0.05, 0.66; p = 0.089; I2 = 0%; 95% prediction interval: –0.28, 0.88). In this meta-analysis, there were no significant differences between low-load and high-load resistance training on hypertrophy of type I or type II muscle fibers. The 95% confidence and prediction intervals were very wide, suggesting that the true effect in the population and the effect reported in a future study conducted on this topic could be in different directions and anywhere from trivial to very large. Therefore, there is a clear need for future research on this topic.

Key words

  • loading zones
  • intensity
  • volume
  • cross-sectional area
  • CSA
Otwarty dostęp

Dynamic Strength Index: Relationships with Common Performance Variables and Contextualization of Training Recommendations

Data publikacji: 31 Aug 2020
Zakres stron: 59 - 70

Abstrakt

Abstract

The purposes of this study were to examine the relationships between dynamic strength index (DSI) and other strength-power performance characteristics and to contextualize DSI scores using case study comparisons. 88 male and 67 female NCAA division I collegiate athletes performed countermovement jumps (CMJ) and isometric mid-thigh pulls (IMTP) during a pre-season testing session as part of a long-term athlete monitoring program. Spearman’s correlations were used to assess the relationships between DSI and CMJ peak force, height, modified reactive strength index, peak power and IMTP peak force and rate of force development (RFD). Very large relationships existed between DSI and IMTP peak force (r = -0.848 and -0.746), while small-moderate relationships existed between DSI and CMJ peak force (r = 0.297 and 0.313), height (r = 0.108 and 0.167), modified reactive strength index (r = 0.174 and 0.274), and IMTP RFD (r = -0.341 and -0.338) for men and women, respectively. Finally, relationships between DSI and CMJ peak power were trivial-small for male (r = 0.008) and female athletes (r = 0.191). Case study analyses revealed that despite similar DSI scores, each athlete’s percentile rankings for each variable and CMJ force-time characteristics were unique, which may suggest different training emphases are needed. Based on the explained variance, an athlete’s IMTP performance may have a larger influence on their DSI score compared to the CMJ. DSI scores should be contextualized using additional performance data to ensure each individual athlete receives the appropriate training stimulus during different training phases throughout the year.

Key words

  • countermovement jump
  • isometric mid-thigh pull, strength
  • peak power
  • rate of force development
  • reactive strength index-modified
Otwarty dostęp

In-Season Strength Training in Elite Junior Swimmers: The Role of the Low-Volume, High-Velocity Training on Swimming Performance

Data publikacji: 31 Aug 2020
Zakres stron: 71 - 84

Abstrakt

Abstract

The aim of this study was to analyze the effect of long-term combined strength training (ST) and plyometrics on strength, power and swimming performances in elite junior swimmers during a competitive season. Ten elite junior swimmers (5 women and 5 men) completed the study (age: 16.6 ± 0.7 years; mass: 62.2 ± 5.4 kg; stature: 1.70 ± 0.07 m). The participants trained twice a week during 20 weeks. The ST program consisted of upper- and lower limbs exercises with low loads and low volume, lifting the load at maximal intended velocity. The effect of the training protocol was assessed using the 1RM in the full squat (SQ) and bench press (BP), jump height (CMJ), the maximal number of repetitions completed in the pull-up (PU) exercise and time during 50-m freestyle. Training program resulted in significant improvements in CMJ (12.1%, ES: 0.57), maximal dynamic strength in the SQ (16.4%, ES: 0.46) and BP (12.1%, ES: 0.34) exercises, the maximum number of repetitions completed during the PU test (90.7%, ES: 0.57) and swimming performance (-3.9%, ES: 0.45). There were no significant differences between both genders. The relative changes in swimming performance showed significant relationship with the relative changes in 1RM of SQ for pooled data (r=-0.66, p<0.05) and the relative changes in the PU exercise in female swimmers (r=-0.99, p<0.05). Therefore, coaches and strength and conditioning professionals should consider including in-season dry-land ST programs within the training routine in order to obtain further improvements in swimming performance.

Key words

  • resistance training
  • swim time
  • vertical jump
  • full squat
  • youth swimmers
Otwarty dostęp

Does Acute Blood Flow Restriction with Pneumatic and Non-Pneumatic Non-Elastic Cuffs Promote Similar Responses in Blood Lactate, Growth Hormone, and Peptide Hormone?

Data publikacji: 31 Aug 2020
Zakres stron: 85 - 97

Abstrakt

Abstract

Blood flow restriction (BFR) can be used during resistance training (RT) through pressure application with pneumatic (pressurized) cuffs (PC) or non-pneumatic (practical) cuffs (NPC). However, PC are expensive and difficult to use in the gym environment compared to NPC. The main aim was to compare, correlate, and verify the hormonal and metabolic responses between PC and NPC during a low-load BFR during RT of the upper-body. The secondary aim was to compare blood lactate (BLa) concentration between pre- and post-exercise (2-min into recovery), as well as growth hormone (GH) and insulin-like growth factor 1 (IGF-1) concentration before, 10-min, and 15-min post exercise. Sixteen trained men randomly and alternately completed two experimental RT protocols of the upper-body : A) RT with BFR at 20% 1RM using PC (RT-BFR-PC) and (B) RT with BFR at 20% 1RM using NPC (RT-BFR-NPC) in the bench press, wide-grip lat pulldown, shoulder press, triceps pushdown, and biceps curl exercises. There was no significant difference in BLa 2-min post exercise (p=0.524), GH 10-min (p=0.843) and 15-min post exercise (p=0.672), and IGF-1 10-min (p=0.298) and 15-min post exercise (p=0.201) between RT-BFR-PC and RT-BFR-NPC. In addition, there was a moderate correlation, satisfactory ICCs, and agreement between both protocols in metabolic and hormonal responses. The experimental sessions promoted significant increases in GH and BLa, but not in IGF-1 (p<0.05). The absence of a significant difference between RT-BFR-PC and RT-BFR-NPC in metabolic and hormonal responses highlight the applicability of NPC as a low-cost and easy-to-use tool for BFR upper-body RT.

Key words

  • katsu training
  • resistance exercise
  • GH
  • lactate
  • IGF-1
Otwarty dostęp

The Effects of Plyometric Conditioning on Post-Activation Bench Press Performance

Data publikacji: 31 Aug 2020
Zakres stron: 99 - 108

Abstrakt

Abstract

The present study aimed to determine the effects of plyometric push-ups as a conditioning activity (CA) on high-loaded bench press performance. Two groups of resistance-trained males age (24.5 ± 2.6 years, body mass 84.8 ± 8 kg) performed one of two CA protocols: 3 sets of 5 repetitions of plyometric push-ups with a 1 min rest interval between sets (PAPE; n=12) or equal time aerobic warm-up (CONT; n=12). Four minutes after completion of the CA protocols the participants performed 3 sets of 3 repetitions of the bench press exercise at 70%1RM and 4 min rest interval between sets to assess post-activation differences in peak power output (PP), mean power output (MP), peak bar velocity (PV), and mean bar velocity (MV) between conditions. The two-way ANOVA revealed significant condition × set interaction effect for PP (p<0.01), MP (p<0.05), PV (p<0.01), and MV (p=0.02). The post hoc for condition × set interaction showed that PAPE caused a significant decrease in PP and PV for P-Set2 and P-Set3 when compared to baseline (BA). The MP and MV for the PAPE condition decreased significantly during the P-Set3 compared to BA and to P-Set1. The t-test comparisons for delta values showed significant differences between PAPE and CONT in PP for P-Set1 – BA (p<0.01), in MP for P-Set2 – P-Set1 (p<0.03) and for P-Set3 – P-Set1 (p=0.04). Furthermore, there were significant differences in PV for P-Set3 – BA; P-Set2 – P-Set1; P-Set3 – P-Set1 (p<0.01; p<0.01; p<0.02 respectively). Finally, there were significant differences in MV for P-Set1 – BA; P-Set2 – P-Set1 and P-Set3 – P-Set1 (p<0.01; p<0.01; p<0.02 respectively). This study demonstrated that plyometric push-ups lead to performance enhancement of the bench press exercise at 70%1RM. The increases in performance were observed only in the first set following the CA, while a significant decrease of these variables was registered in P-Set2 and P-Set3.

Key words

  • push-up
  • PAPE
  • complex training
  • sport performance
  • resistance training
Otwarty dostęp

Influence of the Strap Rewind Height During a Conical Pulley Exercise

Data publikacji: 31 Aug 2020
Zakres stron: 109 - 118

Abstrakt

Abstract

The use of flywheel devices has increased in popularity within resistance training programs. However, little is known about modifiable variables which may affect power output responses, as the rope length and the height level used in a conical pulley device. The aim of this study was to assess the influence of using three different rope lengths (1.5, 2.5 and 3.5 meters) and four different height levels (L1, L2, L3 and L4) on concentric peak power (PPconc), eccentric peak power (PPecc) and eccentric overload (eccentric/concentric PP ratio; EO) during conical pulley exercises (i.e. seated and stand-up row). A total of 29 recreationally trained subjects (25.3±7.1 years; 1.74±0.06 m; 72.5±8.3 kg) took part in the study. Testing sessions consisted of 1 set of 10 repetitions under each condition; experiment 1: seated row exercise using the three different rope lengths; experiment 2: stand-up row exercise using four different height levels of the conical pulley. Results from experiment 1 did not show differences between rope lengths, although a trend for greater PPecc (ES=0.36-0.38) and EO (ES=0.40-0.41) was found when using longer rope lengths (2.5 and 3.5). Experiment 2 showed significant increases in both PPconc and PPecc as the height level used was closer to the cone base (L4). In contrast, EO values were significantly greater when using upper height levels (L1). These results suggest that the height level used during conical pulley exercises highly influences power output responses. Therefore, this variable should be carefully managed depending on the training goal (e.g. power vs hypertrophy).

Key words

  • eccentric overload
  • strength
  • power output
  • flywheel
Otwarty dostęp

Gender and Age Related Differences in Leg Stiffness and Reactive Strength in Adolescent Team Sports Players

Data publikacji: 31 Aug 2020
Zakres stron: 119 - 129

Abstrakt

Abstract

The aim of the present study was to identify potential gender differences in leg stiffness and reactive strength during hopping tasks in 13 to16-year old team sports players. Reactive strength index (RSI) and leg stiffness were obtained in two consecutive seasons from 51 girls (U14: n = 31, U16: n = 20) and 65 boys (U14: n = 32, U16: n = 33). A significant main effect on absolute (U14: p = 0.022, η2= 0.084; U16: p < 0.001, η2= 0.224) and relative leg stiffness (U14 p<0.001; η2= 0.195; U16; p = 0.008, η2= 0.128) for gender was found in both groups with values higher in boys than in girls. For absolute and relative stiffness gender differences in the U14 group were significant in the 1st year only (p=0.027 and p=0.001), and for the U16s in the 2nd year only (p < 0.001 and p = 0.022). For RSI, a significant main effect for gender was observed in the U16 group only (p < 0.001 η2= 0.429) with values significantly higher in boys than in girls in both years of measurement (p = 0.001; p < 0.001). Results of this study support previous limited findings, mostly related to non-athletes, suggesting lower stretch-shortening cycle capability in adolescence female compared to male, however our data only partly supports the theory that quality of neuromuscular functions increases with age until post puberty.

Key words

  • youth
  • neuromuscular
  • stretch-shortening cycle
  • reactive strength index
Otwarty dostęp

Comparison of Muscle Activation and Kinematics in 6-RM Squatting With Low and High Barbell Placement

Data publikacji: 31 Aug 2020
Zakres stron: 131 - 142

Abstrakt

Abstract

The aim of this study was to compare 6-RM muscle activation and kinematics in back squats with low and high barbell placements. Twelve resistance-trained males (23.5 ± 2.6 years, 86.8 ± 21.3 kg, 1.81 ± 0.08 m) with a minimum of 2 years of squatting experience performed a 6-RM using high and low barbell placements while muscle activation of eight muscles and joint kinematics were measured. During high barbell placement squats, lifting time was longer, with lower average velocity than low barbell placement. This was accompanied by a lesser knee flexion angle at the lowest point of the squat, and larger hip flexion angles during high, compared to low barbell squats. Furthermore, peak angular ankle, knee and hip velocities in the descending phase developed differently between conditions. No significant differences in muscle activation were found between conditions. Thus, our data suggests gross muscular adaptations between barbell placements may be similar over time, and therefore, from a muscular development standpoint, both squat styles are valid. Furthermore, unlike the low barbell placement, fatigue may manifest earlier itself in the high barbell squats during 6-RMs as sets progress toward a lifter’s maximal capacity, altering kinematics, especially in the last repetition.

Key words

  • EMG
  • resistance exercise
  • performance
Otwarty dostęp

Genetics of Muscle Stiffness, Muscle Elasticity and Explosive Strength

Data publikacji: 31 Aug 2020
Zakres stron: 143 - 159

Abstrakt

Abstract

Muscle stiffness, muscle elasticity and explosive strength are the main components of athletes’ performance and they show a sex-based as well as ethnicity variation. Muscle stiffness is thought to be one of the risk factors associated with sports injuries and is less common in females than in males. These observations may be explained by circulating levels of sex hormones and their specific receptors. It has been shown that higher levels of estrogen are associated with lower muscle stiffness responsible for suppression of collagen synthesis. It is thought that these properties, at least in part, depend on genetic factors. Particularly, the gene encoding estrogen receptor 1 (ESR1) is one of the candidates that may be associated with muscle stiffness. Muscle elasticity increases with aging and there is evidence suggesting that titin (encoded by the TTN gene), a protein that is expressed in cardiac and skeletal muscles, is one of the factors responsible for elastic properties of the muscles. Mutations in the TTN gene result in some types of muscular dystrophy or cardiomyopathy. In this context, TTN may be regarded as a promising candidate for studying the elastic properties of muscles in athletes. The physiological background of explosive strength depends not only on the muscle architecture and muscle fiber composition, but also on the central nervous system and functionality of neuromuscular units. These properties are, at least partly, genetically determined. In this context, the ACTN3 gene code for α-actinin 3 has been widely researched.

Key words

  • sports genetics
  • genetic markers
  • genetic polymorphism
  • muscle rigidness
  • power
Otwarty dostęp

Unilateral Plyometric Training is Superior to Volume-Matched Bilateral Training for Improving Strength, Speed and Power of Lower Limbs in Preadolescent Soccer Athletes

Data publikacji: 31 Aug 2020
Zakres stron: 161 - 176

Abstrakt

Abstract

This study compared the effects of unilateral and bilateral plyometric training on strength, sprint performance and lower limb power. Sixty-eight preadolescent soccer athletes were randomly assigned to a unilateral plyometric training group (n=23), a bilateral plyometric training group (n=23) and a control group (n=22). Both plyometric training groups trained with equal volumes of unilateral or bilateral exercises for 15 minutes in each session, at which time the control group performed soccer-specific drills. Plyometric exercises were executed twice weekly for 10 weeks during the competitive season. The following tests were performed before and after the intervention: single-leg and double-leg countermovement jump, squat jump, horizontal jumps in different directions, maximal isometric strength of quadriceps and hamstrings, sprint performance, agility and balance. Unilateral plyometric training resulted in greater improvements compared to the control group in the following variables: hamstrings strength (ES: 0.91, p=0.037), 5m sprint time (ES: 0.93, p=0.004), single-leg countermovement jump (ES: 0.90, p=0.006), single- and double-leg squat jump (ES: 0.87, p=0.030 and ES: 0.73, p=0.067, respectively) and single-leg hop performance (ES: 1.01, p=0.004). The only tests where there was an improvement of BPT compared with the CG were the single-leg and double leg SJ (ES: 0.76, p=0.026; ES: 0.70, p=0.050). Quadriceps strength, side hop test, double-leg horizontal jump test, flamingo balance test and modified agility T-test were equally improved in all three groups (p<0.001). In conclusion, unilateral lower-limb plyometric training is more effective in increasing muscle strength and power in preadolescent soccer players when compared to bilateral training or soccer training alone.

Key words

  • single-leg training
  • stretch-shortening cycle
  • performance
  • youth athletes
Otwarty dostęp

Caffeine Ingestion Enhances Repetition Velocity in Resistance Exercise: A Randomized, Crossover, Double-Blind Study Involving Control and Placebo Conditions

Data publikacji: 31 Aug 2020
Zakres stron: 177 - 183

Abstrakt

Abstract

We aimed to examine the effects of placebo and caffeine compared to a control condition on mean velocity in the bench press exercise. Twenty-five resistance-trained men participated in this randomized, crossover, double-blind study. The participants performed the bench press with loads of 50%, 75%, and 90% of one-repetition maximum (1RM), after no supplementation (i.e., control), and after ingesting caffeine (6 mg/kg), and placebo (6 mg/kg of dextrose). At 50% 1RM, there was a significant effect of caffeine on mean velocity compared to control (effect size [ES] = 0.29; p = 0.003), but not when compared to placebo (ES = 0.09; p = 0.478). At 75% 1RM, there was a significant effect of caffeine on mean velocity compared to placebo (ES = 0.34; p = 0.001), and compared to control (ES = 0.32; p < 0.001). At 90% 1RM, there was a significant effect of caffeine on mean velocity compared to placebo (ES = 0.36; p < 0.001), and compared to control (ES = 0.46; p < 0.001). There was no significant difference between placebo and control in any of the analyzed outcomes. When evaluated pre-exercise and post-exercise, 20% to 44% and 28% to 52% of all participants identified caffeine and placebo trials beyond random chance, respectively. Given that the blinding of the participants was generally effective, and that there were no significant ergogenic effects of placebo ingestion, the improvements in performance following caffeine ingestion can be mainly attributed to caffeine’s physiological mechanisms of action.

Słowa kluczowe

  • ergogenic aid
  • supplements
  • mean repetition velocity
Otwarty dostęp

Caffeine Increases Muscle Performance During a Bench Press Training Session

Data publikacji: 31 Aug 2020
Zakres stron: 185 - 193

Abstrakt

Abstract

Previous investigations have established the ergogenic effect of caffeine on maximal muscle strength, power output and strength-endurance. However, these investigations used testing protocols that do not replicate the structure of a regular strength training session. Thus, the aim of this study was to investigate the effect of acute caffeine ingestion on muscle performance during a simulated velocity-based training workout. In a double-blind, randomized and counterbalanced experiment, 12 participants performed two experimental trials after ingesting 3 mg/kg/b.m. of caffeine or a placebo. The trials consisted of 4 sets of 8 repetitions of the bench press exercise at 70% of their one-repetition maximum performed at maximal velocity. Bar velocity was recorded with a rotatory encoder and force, power output and work were calculated. Regarding the whole workout, caffeine increased mean bar velocity (+7.8%; p=0.002), peak bar velocity (+8.7%; p=0.006), mean force (+1.5%; p=0.002), mean power output (+10.1%; p=0.003) and peak power output (+8.2%; p=0.004) when compared to the placebo. The total work performed in the caffeine trial was superior to the placebo trial (7.01±2.36 vs 6.55±2.20 kJ, p=0.001). These results suggest that the acute intake of 3 mg/kg/b.m. of caffeine before a velocity-based strength workout increased muscle performance and the total work performed across the whole training session. Thus, caffeine can be considered as an effective strategy to enhance muscle performance during the bench press training sessions.

Key words

  • resistance exercise
  • muscle strength
  • strength training
  • exercise
  • ergogenic aid
Otwarty dostęp

Transfer of Dry-Land Resistance Training Modalities to Swimming Performance

Data publikacji: 31 Aug 2020
Zakres stron: 195 - 203

Abstrakt

Abstract

A great number of studies focusing on the effects of dry-land resistance training interventions on swimming performance remain inconclusive. It is suggested that transferability of dry-land strength gains to swimming performance appear when dry-land resistance training programs are swim-specific. The main aim of this study was to compare the effects of specific dry-land resistance training on an ergometer with traditional dry-land exercises, and to determine how much of the resistance training effects were transferred to specific swimming conditions. The study included a group of 26 youth competitive male swimmers (age 15.7 ± 0.5 years, height 174.6 ± 6.6 cm, weight 68.4 ± 8.2 kg, training experience 5.8±0.7 years) of regional level. They were randomly allocated to one of two groups: experimental (E) and control (T). Both groups were involved in a 12-week dry-land resistance training concentrated on increasing muscular strength and power output of the upper limbs. Group E used a specialized ergometer (JBA – Zbigniew Staniak), while group T performed traditional resistance exercises. The program consisted of 10 sets of 30 s of exercise with 30 s rest intervals between each set. A two-way repeated measures ANOVA with Tukey HSD post hoc comparisons was used to determine if any significant differences existed between training groups across pretest and posttest conditions. The significance level was set at p ≤ 0.05. Dry-land resistance training modalities were the only differences in training between both groups. Our findings show that rates of transfer are much higher in group E than in group T, which resulted in a significant increase in swimming velocity (by 4.32%, p<0.001; ES=1.23, and 2.78%, p<0.003, ES=0.31, respectively).

Key words

  • swimmers
  • front crawl
  • strength
  • power output
  • ergometer
Otwarty dostęp

Impact of Rest-Redistribution on Fatigue During Maximal Eccentric Knee Extensions

Data publikacji: 31 Aug 2020
Zakres stron: 205 - 214

Abstrakt

Abstract

Redistributing long inter-set rest intervals into shorter but more frequent rest intervals generally maintains concentric performance, possibly due to improved energy store maintenance. However, eccentric actions require less energy than concentric actions, meaning that shorter but more frequent sets may not affect eccentric actions to the same degree as concentric actions. Considering the increased popularity of eccentric exercise, the current study evaluated the effects of redistributing long inter-set rest periods into shorter but more frequent rest periods during eccentric only knee extensions. Eleven resistance-trained men performed 40 isokinetic unilateral knee extensions at 60°·s−1 with 285 s of total rest using traditional sets (TS; 4 sets of 10 with 95 s inter-set rest) and rest-redistribution (RR; 20 sets of 2 with 15 s inter-set rest). Before and during exercise, muscle oxygenation was measured via near-infrared spectroscopy, and rating of perceived exertion (RPE) was recorded after every 10th repetition. There were no differences between protocols for peak torque (RR, 241.58±47.20 N; TS, 231.64±48.87 N; p=0.396) or total work (RR, 215.26±41.47 J; TS, 209.71±36.02 J; p=0.601), but moderate to large effect sizes existed in later repetitions (6,8,10) with greater peak torque during RR (d=0.66-1.19). For the entire session, RR had moderate effects on RPE (RR, 5.73±1.42; TS, 6.09±1.30; p=0.307; d=0.53) and large effects on oxygen saturation (RR, 5857.4±310.0; TS, 6495.8±273.8; p=0.002, d=2.13). Therefore, RR may maintain peak torque or total work during eccentric exercise, improve oxygen utilization at the muscle, and reduce the perceived effort.

Key words

  • muscle oxygenation
  • velocity
  • fatigue
  • resistance training
  • isokinetic
  • cluster sets
Otwarty dostęp

Effects of Different Inertial Load Settings on Power Output Using a Flywheel Leg Curl Exercise and its Inter-Session Reliability

Data publikacji: 31 Aug 2020
Zakres stron: 215 - 226

Abstrakt

Abstract

This study aimed to analyze the influence of the inertial load on both concentric and eccentric power output production during the flywheel leg curl exercise, and to assess the reliability of power output variables. Sixteen participants (8 males, 8 females) attended 4 testing sessions. During testing, participants performed one set of eight repetitions using a specific inertial load (0.083, 0.132, 0.182, 0.266 and 0.350 kg·m2) with a flywheel leg curl exercise. Concentric (CON) power, eccentric (ECC) power and the ECC/CON ratio were analyzed. The reliability analysis between sessions was performed. A significant interaction of inertia load x gender was found in CON power (p < 0.001) and in ECC power (p = 0.004), but not in the ECC/CON ratio (p = 0.731). A significant with-in (inertia loads) effect was found in CON power (p < 0.001) and in ECC power (p < 0.001), but not in the ECC/CON ratio (p = 0.096). CON power showed very high reliability scores, ECC power showed high to very high reliability scores, while the ECC/CON ratio ranged from poor to moderate. A significant between gender effect was found in CON power (p < 0.001) and in ECC power (p < 0.001), but not in the ECC/CON ratio (p = 0.752). This study is the first to report that power output in the flywheel leg curl exercise is altered by the inertia load used, as well as power output is different according to gender. CON and ECC power output presents high to very high reliability scores, and the ECC/CON ratio should not be used instead. These results can have important practical implications for testing and training prescription in sports.

Key words

  • eccentric overload
  • iso-inertial
  • resistance training
  • hamstring muscles
Otwarty dostęp

Resistance Exercise Intensity Does Not Influence Neurotrophic Factors Response in Equated Volume Schemes

Data publikacji: 31 Aug 2020
Zakres stron: 227 - 236

Abstrakt

Abstract

The aim of the present study was to evaluate the effects of 2 different intensities of resistance training (RT) bouts, performed with the equated total load lifted (TLL), on the acute responses of neurotrophic factors (NFs) (brain-derived neurotrophic factor [BDNF]; and nerve growth factor [NGF]), as well as on metabolic (lactate concentration) and hormonal (salivary cortisol concentration) responses. Thirty participants (males, 22.8 ± 2.3 years old, 177 ± 6.8 cm, 75.5 ± 7.9 kg, n = 15; and females, 22.2 ± 1.7 years, 163.7 ± 6.5 cm, 57 ± 7.6 kg, n = 15) performed 2 separate acute RT bouts with one week between trials. One bout consisted of 4 sets of 5 submaximal repetitions at 70% of 1RM and the other of 4 sets of 10 submaximal repetitions at 35% of 1RM for each exercise. Both RT bouts were conducted using the bench press and squat exercises. The TLL in each bout (determined by sets x repetitions x load [kg]) was equated. Serum BDNF, serum NGF, salivary cortisol, and blood lactate concentration were determined pre- and post-RT. No significant pre- to post-exercise increase in neurotrophic factors (p > 0.05; BDNF; effect size = 0.46 and NGF; effect size = 0.48) was observed for either of the RT bouts. A similar increase in blood lactate concentration was observed pre- to post-exercise for both RT bouts (p < 0.05). Cortisol increased similarly for both RT bouts, when compared to the resting day condition (p < 0.05). In conclusion, the results suggest that, despite differences in RT schemes, a similar acute neurotrophic, metabolic and hormonal response was observed when the TLL is equated.

Key words

  • BDNF
  • NGF
  • Cortisol
  • Blood Lactate
  • Resistance Training

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