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Effects of Plyometric Training with and without Additional Load on Muscular Force Indices and Explosive Power in Male Soccer Players
Abstract
This study investigated the effect of plyometric training with and without additional load on young male soccer players' jumping ability and isokinetic strength. Methods: In this randomized controlled trial, 39 U-17 male trained soccer players were randomly divided into plyometric training with additional load (PT+AL), plyometric training with just bodyweight (PTBW) and control (CON) groups. PT+AL and PTBW were performed for six weeks (2 days/week) along with habitual soccer training. Absolute peak torque (APT), average peak torque (AvPT), time-to-peak torque (TPT), average rate of force development (AvRFD), vertical jump height (VJH), standing long jump (SLJ), and 15-second repeated jump tests (RJ15s) were assessed before and after the interventions. The findings showed that the performance of knee extensors in TPT-60°/s (19.6% vs 0.8%) and AvRFD-60°/s (36.3% vs 3.8%), and knee flexors in APT-60°/s (18.8% vs 4.3%), AvPT-60°/s (19.2% vs -2.6%), AvPT-120°/s (20.7% vs 2.8%), AvRFD-60°/s (80.6% vs 20.2%), and AvRFD-120°/s (43.5% vs 8.9%) significantly increased after PT+AL, compared to the CON (P<0.05). Also, a significant improvement in jumping ability (VJH:12.5% vs 2.3%, SLJ: 6.8% vs 2.7% and RJ15s: 36.4% vs -1.7%) was observed in PT+AL compared to CON (P<0.05). Additionally, PTBW also improved the performance of knee flexors in TPT-120°/s (15.8% vs 1.9%) and AvRFD-120°/s (28.2% vs 8.9%), as well as RJ15s performance (26.2% vs -1.7%) compared to the CON (P<0.05). Furthermore, knee flexors AvRFD-60°/s (80.6% vs 25.4%) increased significantly after PT+AL, compared to PTBW (P<0.05). SO, plyometric training, with or without additional load, improved young male soccer players' strength and jumping ability. However, strength parameters - especially the rate of force development - showed a greater increase following PT + AL compared to PTBW.
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Featured Application
The purpose of the present study was to compare the effects of 8 weeks of contrast strength training versus combined isometric and plyometric training on sprinting, change of direction, throwing, and handgrip strength. The combined approach yielded greater enhancements in sprinting and ball throwing velocity compared to the contrast group. Both training strategies significantly improved most neuromuscular performance measures compared to the control group.
Abstract
Exploring resistance training methods is crucial for optimizing performance programs. Isometric muscle actions have gained popularity in athletic training, but their impact on dynamic performance is uncertain. Isolated isometric actions also lack ecological validity. We compared the effects of 8-week combined isometric and plyometric (COMB) training and contrast strength training (CST) programs on junior male handball players. Thirty-six male first national division players (17.6 ± 1.0 years) were enrolled and randomly assigned to COMB, CST, or control (CONT) groups (all n = 12). Sprinting, change of direction, ball throwing velocity, jumping, and strength were assessed pre- and post-intervention. A significant group × time interaction was observed between the COMB and CONT groups for 20 and 30 m sprints (p ≤ 0.002) and between the COMB and CST groups (p ≤ 0.042). The COMB group had the largest improvements in change of direction and the modified T-test, with significant group × time interactions between the COMB and CONT groups (p ≤ 0.021). Significant group × time interactions were observed between the COMB and CST groups and between the COMB and CONT groups for 3 step running throw (p = 0.003; p < 0.001), running throw (p = 0.02; p = 0.031), and jumping throw (p = 0.001; p < 0.001). Countermovement jump showed a significant group × time interaction (p = 0.014), with the COMB group outperforming the other groups. Generally, COMB yielded larger improvements than CST. Coaches should consider incorporating a combination of isometric and plyometric exercises for in-season strength training.
The purpose of this systematic review was to summarize the associations of eccentric force variables during jumping and eccentric lower-limb strength with vertical jump performance. A literature search was conducted in September 2022 using PubMed, Web of Science, and Scopus. Thirteen cross-sectional studies investigating the relationship between eccentric force and strength variables, such as force, rate of force development (RFD), power, time, and velocity, and vertical jump performance, including the jump height, reactive strength index (RSI), and reactive strength index-modified (RSImod), were included in this systematic review. As eccentric strength, variables during the unloading-to-braking phase of countermovement jump (CMJ) (force, RFD, etc.) and the eccentric force of the squat movement and knee joint were included. The CMJ height, RSImod, and drop jump RSI were included to analyze the vertical jump performance. The modified form of the Downs and Black checklist was used to evaluate quality. Associations between the force and RFD during the descending phase of the CMJ and jump height were observed in some studies but not in others, with differences between the studies. Some studies reported associations between the force and/or RFD during the descending phase of the CMJ and RSImod of the CMJ, with no differences among their results. In addition, there are associations of the eccentric forces during squatting and knee extension with the CMJ and the drop jump heights and RSI of the drop jump. The eccentric force variables in the CMJ and RSImod are related; however, their relationship with jump height remains unclear. Furthermore, improved eccentric muscle strength may contribute to vertical jump height because of the associations of the eccentric strength during knee extension and squatting with jump height.
The purpose of this study was to evaluate the speed, agility, and explosive strength performance of elite basketball players over an 8-week plyometric training program. Fifteen elite male college basketball players in Taiwan (average age 22.16 ± 0.85 years old) were publicly recruited. All participants received 24 plyometric training courses three times per week for 8 weeks, and the courses were implemented pre- and post-test. The speed and agility test items were divided into a 20 m sprint and a T-shaped run. In the explosive strength test, a force plate was used to measure countermovement jump to understand the pre- and post-test differences in all the test indicators, including the rate of force development, time of the rate of force development, ground reaction forces for the moment of jumping, duration of passage, and jump height. It was found that, after the participants underwent the plyometric training program, the body mass index and body fat percentage were significantly reduced, the skeletal muscle mass was significantly increased, and the post-test scores for speed and agility improved significantly. All the participants exhibited a steeper gradient for the rate of force development (r = −0.816~−0.963) and a shorter time for the rate of force development (0.107~0.232 s). The ground reaction forces reached 1509.61~2387.11 Newtons. The duration of passage reached 0.643 s, and the jump height reached 0.624 m. The conclusion was that the plyometric training program can increase muscle volume in the lower limbs and legs, increase the rate of force development, and shorten the jumping time, thereby enhancing explosive strength.
The purpose of this study is to understand the significance of plyometric training on the enhancement of sports performance. To achieve the purpose, the proliferation of peer-reviewed articles published on plyometric training, including systematic reviews, book chapters, and meta-analysis were taken. In this review, the study of plyometrics and its impact on various parameters of athlete(s) is done. As per literature, plyometric exercises have the potential in improving the huge range of sports performance i.e. sprint, speed, explosiveness, muscular strength, agility, jump height and broadness with the application of systematic and well-designed plyometric training modality. There are many key issues pertaining to plyometric training program are remaining to be resolved unless the significance of plyometrics is well known. The consequences in this review, highlight the significance and issues related to plyometric training modality and allows suggesting the implication of a specific training program as an incredibly effective program and also provides future directions for research. ________________________________________________________________________________
Background: Sprinting speed as a derivative of lower-body power is considered to be the most vital component of physical ability of the players. Traditional training methods fail to improve sprinting speed of the experienced players up to a certain limit that demands newer training means for further development of speed. Hypergravity Training (HT) has been identified as such a new type of training that was used by few researchers for the improvement of sprinting speed and power of the experienced rugby and soccer players. But it has still not been implemented on the cricketers for the development of sprinting speed. Objective: Therefore, the current randomized control trial was directed to assess the development of sprinting speed of the cricketers through the implementation of HT in comparison with the Normalgravity Training (NT) condition. Method: The present study was a quasi-experimental research work. One hundred and five (N=105) state cricketers were selected as subjects. The participants were split into three equal groups (n=35 each) viz. i) Normalgravity Training Group (NGTG), ii) Hypergravity Training Group (HGTG) iii) Control Group (CG). NGTG HGTG groups underwent the same exercise protocol for the periods of twelve weeks in normal hypergravity conditions respectively whereas CG was free from the training intervention. Sprinting speed of the cricketers was measured by a 30m run test. ANCOVA preceded by Tukey’s LSD test were performed for data analysis. Statistical significance was examined at p.05 level. Results: Significant F-value (F=61.122; p 0.001) was observed. Sprinting speed of both training groups (NGTG HGTG) improved significantly (Mean Diff=1.28 0.86; Critical Diff =0.41) in comparison to the CG. HGTG also differed significantly (Mean Diff =0.42; Critical Diff =0.41) when compared with NGTG in sprinting speed. Conclusions: The sprinting speed of HGTG improved better than NGTG. Therefore, HT is found as an effective training means for developing sprinting speed.
Introduction
Training methods that increase muscle strength have an important effect on basketball.
Objective
This study was planned to investigate the effect of a 12-week resisted plyometric training program for isokinetic muscle strength in young basketball players.
Methods
Thirty-five male athletes who participate in regular basketball training were randomly assigned to one of three groups: the control group (C), the plyometric exercise group (P), and the resisted plyometric exercise group (RP). All the players participated in the standard basketball training program 5 days a week for 12 weeks. While the control group performed only standard basketball training, the P group and the RP group participated in plyometric and resisted plyometric exercise programs, respectively, 3 days a week. Vertical jump height and isokinetic muscle strength at 60, 180 and 300°s⁻¹ were measured at the beginning and end of the study.
Results
The plyometric and resisted plyometric training programs did not alter vertical jump performance. However, isokinetic muscle strength increased at all angles in the P and RP groups.
Conclusion
Plyometric and resisted plyometric training programs applied for 12 weeks have a positive effect on muscle strength in young basketball players. Level of evidence II; Therapeutic studies - investigation of treatment results.
Keywords:
Basketball; Muscle strength dynamometer; Training; Athletic performance; Adolescent
The aim of this review was to describe and summarize the scientific literature on programming parameters related to jump or plyometric training in male and female soccer players of different ages and fitness levels. A literature search was conducted in the electronic databases PubMed, Web of Science and Scopus using keywords related to the main topic of this study (e.g., “ballistic” and “plyometric”). According to the PICOS framework, the population for the review was restricted to soccer players, involved in jump or plyometric training. Among 7556 identified studies, 90 were eligible for inclusion. Only 12 studies were found for females. Most studies (n = 52) were conducted with youth male players. Moreover, only 35 studies determined the effectiveness of a given jump training programming factor. Based on the limited available research, it seems that a dose of 7 weeks (1–2 sessions per week), with ~80 jumps (specific of combined types) per session, using near-maximal or maximal intensity, with adequate recovery between repetitions (<15 s), sets (≥30 s) and sessions (≥24–48 h), using progressive overload and taper strategies, using appropriate surfaces (e.g., grass), and applied in a well-rested state, when combined with other training methods, would increase the outcome of effective and safe plyometric-jump training interventions aimed at improving soccer players physical fitness. In conclusion, jump training is an effective and easy-to-administer training approach for youth, adult, male and female soccer players. However, optimal programming for plyometric-jump training in soccer is yet to be determined in future research.
Background
Plyometric training (PT) has been widely studied in sport science. However, there is no review that determines the impact of PT on the structural variables and mechanical properties of the lower limbs and physical performance.
Objective
The aim of this systematic review and meta-analysis was to determine the effects of PT on lower body muscle architecture, tendon structure, stiffness and physical performance.
Methods
Five electronic databases were analysed. The inclusion criteria were: (1) Availability in English; (2) Experimental studies that included a PT of at least eight sessions; and (3) Healthy adults subjects. Four meta-analyses were performed using Review Manager software: (1) muscle architecture; (2) tendon structure; (3) muscle and tendon stiffness; (4) physical performance.
Results
From 1008 search records, 32 studies were eligible for meta-analysis. Muscle architecture meta-analysis found a moderate effect of PT on muscle thickness (Standard Mean Difference (SMD): 0.59; [95% Confidence Interval (CI) 0.47, 0.71]) and fascicle length (SMD: 0.51; [95% CI 0.26, 0.76]), and a small effect of PT on pennation angle (SMD: 0.29; [95% CI 0.02, 0.57]). The meta-analysis found a moderate effect of PT on tendon stiffness (SMD: 0.55; [95% CI 0.28, 0.82]). The lower body physical performance meta-analysis found a moderate effect of PT on jumping (SMD: 0.61; [95% CI 0.47, 0.74]) and strength (SMD: 0.57; [95% CI 0.42, 0.73]).
Conclusion
PT increased the thickness, pennation angle and fascicle length of the evaluated muscles. In addition, plyometrics is an effective tool for increasing tendon stiffness and improving jump and strength performance of the lower body.
Purpose
The purposes of this study were to describe the fitness and hormonal levels according to playing time (PT) (i.e., PT during season less (PT1) or more (PT2) than 50% of the total time) and maturation level (ML) (i.e., normal (ML1) and early maturity levels (ML2)), and to analyze the differences between groups for the measures of aerobic capacity, anaerobic power, power performance, and hormonal concentrations.
Methods
Twenty-four youth footballers of a U16 team participated in this study. Anthropometric measures, maturity status, growth hormone, insulin-like growth factor (IGF-1), maximal oxygen uptake, fatigue index, and countermovement jump were collected.
Results
Significant differences were found between both PT and ML groups for maturational status, aerobic capacity, power performance, and IGF1 concentrations. The interaction of PT and ML revealed significant differences for maturity offset and power performance. When using the skeletal age as a covariant, the previously significant differences found were reduced only to the fatigue index measure.
Conclusions
The response variables analyzed in the present study seem to be influenced by PT and ML. This must be considered when planning training, and coaches must be sensible to these effects as they may assume a preponderant role in PT.
The aim of this study was to examine the effects of an 8-week in-season plyometric training (PT) program on the physical performance and neuromuscular adaptations of female basketball players. Twenty-seven elite female basketball players (aged 21.0 ± 2.6 years) were assigned between an experimental group (n = 15) who substituted a part of their usual training with biweekly PT, and a control group (n = 12) who maintained their standard basketball training. Analyses of variance and co-variance assessed changes in 10, 20, and 30 m sprint times, ability to change direction (T-test) and jumping ability [squat jump (SJ) and countermovement jump (CMJ)] with electromyographic assessment of the vastus lateralis, vastus medialis, and rectus femoris muscles during jumping and meassurement of the isokinetic strength of the knee muscles. After 8 weeks of the plyometric program the experimental group enhanced change of direction performance (Δ = −3.90%, d = 0.67) and showed a greater thigh cross sectional area (Δ = 9.89%, d = 0.95) relative to controls. Neural adaptations included significant improvements of EMG parameters for the vastus medialis muscle during Squat Jumping (Δ = 109.3%, d = 0.59). However, trends to improvements of sprinting times and jumping performances did not reach statistical significance. In addition, there were no gains in the peak torque and the average power of the quadriceps and hamstring muscles at either slow or moderate test speeds. We conclude that 8-weeks of PT (72–126 jumps) was insufficient to improve many of the variables associated with basketball performance in our subject-group. Further studies of female basketball players, extending the program period and increasing the intensity and speed of jumps are recommended in the search for more significant results.
There is a growing interest in knowing the relationship between biological maturation and sport performance-related variables of young athletes. The objective of this study is to analyze the relationship between biological maturation, physical fitness, and kinanthropometric variables of athletes during their growing period, according to their sex. The systematic review and meta-analysis followed the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement and the search protocol was registered in PROSPERO, code: CRD42020208397. A search through the PubMed, Web of Sciences, and EBSCO databases was performed. A total of 423 studies were screened and 13 were included in the meta-analysis. The meta-analysis was completed by using the mean and standard deviation of each variable according to each maturation status (early, on time, or late). Differences depending on maturation were found on physical fitness, with better results in the advanced maturational groups in the male population (standard mean difference (SMD) = 0.17–2.31; p < 0.001–0.05). Differences depending on maturation were found for kinanthropometric variables in males (SMD = 0.37–2.31; p < 0.001–0.002) and height and body mass in females (SMD = 0.96–1.19; p < 0.001). In conclusion, the early maturation group showed higher values in kinanthropometric variables and better results in physical fitness, highlighting the importance of the maturational process in the talent selection programs. Despite that, more research is needed to clarify the relationship of maturation with the other variables on female populations and the changes in the muscle and bone variables during the maturation processes of both sexes.
Background: Dynamic knee valgus (DKV) is defined as a combination of excessive femoral adduction, internal rotation, tibial internal torsion, and the medial movement of the knee. It appears that the athletes with DKV are at higher risk of developing knee injuries. Objective: The aim of this study was to evaluate whether the reactive neuromuscular training would improve whole-body dynamic balance and knee joint position sense (JPS) in women with the dynamic knee valgus. Methods: A controlled laboratory study was conducted on 28 female athletes with DKV. The single leg
squat test was used to assess the DKV. All participants performed the reactive neuromuscular training, stationary cycling and resting sessions on three different days in a random order. The knee JPS and balance in the participants were measured immediately before and after the interventions. Kinematic analysis was used to measure the knee JPS in sagittal and frontal planes. In this regard, captured photos in the sagittal and frontal planes were analyzed using Kinovea software. The Y-balance test was applied to measure the balance. The data were analyzed by the repeated measures analysis of variance with a Bonferroni correction. Results: The results of the repeated measures analysis of variance showed that there was a significant difference between the sessions with respect to knee JPS in sagittal (F(2, 54) = 3.323, p = .047) and frontal (F(2, 54) = 23.83, p = .001) planes, respectively. Also, a significant difference in Y-balance test scores was observed between the sessions (F(2, 54) = 9.12, p = .001). Conclusions: The results
of this study showed that reactive neuromuscular training improved joint position sense and balance in individuals with DKV. The findings of this study may provide a basis for developing injury prevention and rehabilitation strategies in athletes with DKV.
Background:
Weight vest training (WVT) is a strategy used to improve the physical performance of athletes. The objective of this study was to determine the effects of different training strategies with weight vests on vertical jump and change-of-direction ability (CODA) in male volleyball athletes.
Methods:
Fifteen volleyball athletes (22.87 ± 3.04 years, 83.22 ± 10.84 kg, 1.86 ± 0.69 m) participated in a six-week training programme and were randomized into three groups: weight vest plyometric training (WPG), weight vest technical-tactical training (WTG) and a control group (CG). The additional weight of 7.5% of individual body mass was employed in the experimental groups. Before and after the WVT, athletes performed countermovement vertical jump (CMJ) and CODA (T'test) tests.
Results:
Two-way ANOVA with repeated measures showed that CMJ height increased in all training groups (p < 0.05), with the WTG inducing greater CMJ height gains in comparison to the CG (p < 0.05). According to magnitude-based inference, the effects of the WTG strategy were "very likely" beneficial for the CMJ compared to the CG. In addition, T'test time decreased similarly among the three training groups (p < 0.05).
Conclusions:
The results suggest that WVT may be incorporated in a volleyball training routine as an effective strategy for improving the CMJ performance in male volleyball athletes.
James, LP, Suchomel, TJ, Comfort, P, Haff, GG, and Connick, M. Rate of force development adaptations after weightlifting-style training: the influence of power clean ability. J Strength Cond Res 36(6): 1560-1567, 2022-This experiment examined changes to the rate of force development (RFD) expressed under loaded jump conditions between individuals with a higher (stronger) and lower (weaker) weightlifting performance (as assessed by the 1 repetition maximum [RM] power clean) after training with the weightlifting derivatives. Two groups of markedly different weightlifting ability undertook 10 weeks of training with the power clean variants, snatch pulls, and jump squats across heavy and light conditions. Testing was performed at baseline, after 5 weeks of training (mid-test) and after training (post-test). During testing, RFD was assessed under a series of loads (20-80% squat 1RM) through the jump squat. Furthermore, the force-velocity relationship, and unloaded jump strategy (through the force-time curve waveform), were also examined. Very large change (Hedge's g, 95% confidence interval [g] = 2.10, 1.24 to 4.16) in RFD at 20% 1RM at mid-test occurred within the stronger group. Conversely, a small increase (g = 0.27, 0.53-1.91) among the weaker subjects existed in this measure at mid-test, reaching a moderate increase at post-test (g = 0.71, -0.18 to 2.15). Limited improvements were seen by the stronger subjects in RFD at 60 and 80% 1RM at either mid-test (60%: g = 0.27, -0.75 to 1.33; 80% = 0.02, -1.01 to 1.00) or post-test (60%: g = 0.52, -0.38 to 1.80; 80% = -0.26, -1.23 to 0.77). The stronger group experienced a shift throughout the force-velocity relationship while a more force-dominant adaptation occurred in weaker subjects. Differences in jump strategy between groups were also noted. Such training will elicit practically different adaptations in rapid force production depending on the individual's baseline weightlifting ability.
Background:
Endocrine mechanisms can be a determining factor in the neuromuscular performance of young athletes.
Objective:
The objective of the present study was to relate maturational and hormonal markers to neuromuscular performance, as well as to verify whether young athletes with different testosterone levels show differences in muscle strength.
Methods:
The sample consisted of 37 young male Brazilian athletes (11.3 ± 0.94 years) who were members of a sports initiation project. Hormonal markers were analyzed biochemically by blood samples, and maturation markers by mathematical models based on anthropometry. Body composition was verified by tetrapolar bioimpedance. The performance of upper and lower limb strength and body speed were analyzed.
Results:
Hormonal and maturational markers were related to neuromuscular performance (p < 0.05). Young people with higher testosterone levels showed higher muscle strength (p < 0.05). Artificial neural networks showed that testosterone predicted the performance of upper limbs by 49%, and maturation by 60%. Maturation foreshadowed the performance of lower limbs by 30.3%.
Conclusion:
Biological maturation and hormonal levels can be related to neuromuscular performance, and young people with higher testosterone levels show superior muscle strength in relation to the others.
Problem Statement: The performance in Karate mainly depends on aerobic capacity but particularly on explosive muscular strength production. Plyometric training has been previously shown to increase power, strength, and explosive athletic ability. However, scarce data exist regarding the training-induced changes in power, muscle strength, and rate of force development (RFD) in Karate athletes after plyometric or Kumite training. Purpose: The purpose of this study was to examine the effect of a 6-week plyometric training on maximum power, muscle strength, and RFD in young competitive Karate athletes. Methods: A total of 12 young competitive Karate athletes (N = 10 males and N = 2 females) were divided into plyometric (PG, N = 6) and Kumite (KG, N = 6)groups and followed 2 training sessions for 6 weeks of either plyometric or Kumite training. Measurements were performed before and after training intervention and included countermovement jumps (CMJ), maximum isometric RFD and peak torque (PT), standing long jump, and upper body seated medicine ball throws. Results: No significant differences were observed between groups for CMJ and RFD (p>0.05). Significant difference was determined between PG and KG in isometric PT (PG: 9.52 ± 3.64% vs. KG: 1.75 ± 6.91%, p = 0.03). Standing long jump performance considerably increased for PG compared to that for KG (PG: 4.32 ± 4.97% vs. KG: −1.12 ± 3.51%, p = 0.05). The performance in seated medicine ball throws increased overtime only in PG by 4.8 ± 3.55% (p = 0.017); however, no difference was observed between the groups (p>0.05). Conclusions: The results of this study suggest that 6 weeks of specific plyometric training increases lower body power and strength as well as upper body power performance in young Karate athletes. Therefore, coaches may effectively use plyometric training to increase upper and lower body muscle power in young Karate athletes.
Traditional, assisted and resisted plyometrics are considered to be effective training methods for improving vertical jump performance. The purpose of this systematic review and meta-analysis was to compare effectiveness of traditional, assisted and resisted plyometric methods on vertical jumping ability in adults. Available literature was searched using MEDLINE (via EBSCO), SPORTDiscus (via EBSCO), Scopus and Web of Science databases. The methodological quality of studies was assessed using the PEDro scale. Peer-reviewed studies were accepted only if they met all eligibility criteria: (a) healthy adults mean age > 18 years (b) training program based on plyometric exercises (c) the study reported on vertical jump height for the countermovement jump or drop jump performance. Of the 5092 articles identified, 17 studies were included in the qualitative and quantitative analyses. Both funnel plot analysis and Egger's test (p = 0.04) indicated publication bias for the comparison of resisted plyometrics and control condition. No publication bias was found for the other meta-analyses (p > 0.05). The effects of the traditional and assisted plyometric methods, when compared with the control condition (a non-plyometric condition), on jump height were moderate (SMD = 0.68, 95% CI 0.37 to 0.99, p < 0.0001; SMD = 0.70, 95% CI 0.20 to 1.20, p = 0.006, respectively). The effects of the resisted plyometric methods, when compared with the control condition, on a jump height was small (SMD = 0.48, 95% CI 0.17 to 0.79, p = 0.002). There were no significant differences between the training effects of the assisted and traditional plyometric interventions on jump height (SMD = 0.62, 95% CI-1.66 to 2.91, p = 0.59), nor between the resisted and traditional plyometric training programs (SMD = 0.2, 95% CI-0.19 to 0.23, p = 0.86). Traditional, assisted and resisted plyometric methods are effective training modalities for augmenting vertical jump performance in healthy adults. Resisted and assisted plyometric methods are equally effective as the traditional plyometric method in improving vertical jumping ability in healthy adults.
Background
Agility in general and change-of-direction speed (CoD) in particular represent important performance determinants in elite soccer.
Objectives
The objectives of this study were to determine the effects of a 6-week neuromuscular training program on agility performance, and to determine differences in movement times between the slower and faster turning directions in elite soccer players.
Materials and Methods
Twenty male elite soccer players from the Stade Rennais Football Club (Ligue 1, France) participated in this study. The players were randomly assigned to a neuromuscular training group (NTG, n = 10) or an active control (CG, n = 10) according to their playing position. NTG participated in a 6-week, twice per week neuromuscular training program that included CoD, plyometric and dynamic stability exercises. Neuromuscular training replaced the regular warm-up program. Each training session lasted 30 min. CG continued their regular training program. Training volume was similar between groups. Before and after the intervention, the two groups performed a reactive agility test that included 180° left and right body rotations followed by a 5-m linear sprint. The weak side was defined as the left/right turning direction that produced slower overall movement times (MT). Reaction time (RT) was assessed and defined as the time from the first appearance of a visual stimulus until the athlete’s first movement. MT corresponded to the time from the first movement until the athlete reached the arrival gate (5 m distance).
Results
No significant between-group baseline differences were observed for RT or MT. Significant group x time interactions were found for MT (p = 0.012, effect size = 0.332, small) for the slower and faster directions (p = 0.011, effect size = 0.627, moderate). Significant pre-to post improvements in MT were observed for NTG but not CG (p = 0.011, effect size = 0.877, moderate). For NTG, post hoc analyses revealed significant MT improvements for the slower (p = 0.012, effect size = 0.897, moderate) and faster directions (p = 0.017, effect size = 0.968, moderate).
Conclusion
Our results illustrate that 6 weeks of neuromuscular training with two sessions per week included in the warm-up program, significantly enhanced agility performance in elite soccer players. Moreover, improvements were found on both sides during body rotations. Thus, practitioners are advised to focus their training programs on both turning directions.
This systematic review aimed to quantify the acute and longitudinal effects that occur with weighted vests during sprint-running. PubMed, SPORTDiscus, and Web of Science were searched using the Boolean phrases (vest OR trunk) AND (sprint*) AND (resist* OR weight OR load*). From 170 articles retrieved, 11 studies (6 acute, 5 longitudinal) met the inclusion criteria. Vest loads (5–40% body mass) were found to significantly increase acute over-ground times (10–50 m 4.1–16.9%, effect sizes [ES] = 0.93–3.11) through significantly decreased velocity (−2.2% to −17.3%, ES = −0.41 to −3.19), horizontal force (−5.9% to −22.1%, ES = −0.85 to −3.30), maximal power (−4.3% to −35.6%, ES = −0.32 to −3.44), and flight times (−8.3% to −14.6%, ES = −0.88 to −1.03), while increasing contact times (14.7–19.6%, ES = 1.80–3.17). Treadmill sprints were less effected until loads >11% body mass were used. Improvements in velocity (1.2–1.3%, ES = 0.24–0.37) and times (10–50 m 1.2–9.4%, ES = 0.25–3.30) were found in longitudinal studies (5.6–18.9% body mass, 3–7 weeks). Future studies should focus on determining the optimum load and volume to clearly establish the training benefits of this form of resisted sprinting.
The aim of the study was to investigate the rate of force development (RFD) and muscle architecture early adaptations in response to training with fast- or slow-velocity eccentric squats. Eighteen young novice participants followed six weeks (two sessions/week) of either fast-velocity (Fast) or slow-velocity (Slow) squat eccentric-only training. Fast eccentric training consisted of nine sets of nine eccentric-only repetitions at 70% of 1-RM with <1 s duration for each repetition. Slow eccentric training consisted of five sets of six eccentric-only repetitions at 90% of 1-RM with ~4 sec duration for each repetition. Before and after training, squat 1-RM, countermovement jump (CMJ), isometric leg press RFD, and vastus lateralis muscle architecture were evaluated. Squat 1-RM increased by 14.5 ± 7.0% (Fast, p < 0.01) and by 5.4 ± 5.1% (Slow, p < 0.05). RFD and fascicle length increased significantly in the Fast group by 10–19% and 10.0 ± 6.2%, p < 0.01, respectively. Muscle thickness increased only in the Slow group (6.0 ± 6.8%, p < 0.05). Significant correlations were found between the training induced changes in fascicle length and RFD. These results suggest that fast eccentric resistance training may be more appropriate for increases in rapid force production compared to slow eccentric resistance training, and this may be partly due to increases in muscle fascicle length induced by fast eccentric training.
Plyometric training can improve jumping performance and running velocity in both pubertal and prepubertal populations. It has been shown that jumps of various kinds can also precede the specific session of one's sport, with clear improvements on the various performances of jumping or running. However, it is unclear whether the resulting improvement in explosive performance is because of introduction of a new training regimen or whether it merely reflected the response to an additional training load. Thus, this randomized controlled trial aimed to examine the effect of a combined plyometric and traditional athletics training on speed and explosive strength of the lower limbs. Participants (22 boys, 13-14 yr) were randomly assigned to an 8-wk experimental group(EG, n = 10) that performed plyometric training or a control group (CG, n = 12) that continued their traditional training. The EG performed twice weekly sessions of plyometrics (15 min.), in addition to their standard training without increasing the total training time (90 min.). At baseline and after training all participants were tested on the 20-m sprint (time) and Squat Jump (power, velocity, force and height). The EG group showed significantly (p < 0.05) improvement than CG in the 20-m sprint time (-0.1 vs. 0.1 sec) and Squat Jump (160.8 vs. -31.9 W; 0.3 vs. -0.2 m·s -1 ; 45.3 vs. -6.3 N; 10.9 vs. -2.2 cm) following training. Eight weeks of plyometric training added to the
standard program of athletics was highly likely to improve the lower limbs speed and explosive strength in young athletes. Our findings highlight the potential value of combined training methods in a conditioning program aimed at maximizing power performance in youth.
Jump tests and isokinetic dynamometer assessments are widely used in sports to identify parameters of strength and power
development. Understanding the relationship between these variables can help in the selection of more specific parameters to
assess the strength of knee joint muscles on isokinetic dynamometer in volleyball players. The objective of this literature
review was to summarize studies that have analyzed the relationship between performance in jump tests with strength
generation capacity in knee isokinetic dynamometry assessments among volleyball players, besides investigating whether
muscle imbalances of the knee joint can interfere with jump performance. The reviewed studies resulted from a search on
PubMed and Scielo databases. A total of 106 articles were found, 6 of which were used for final analysis. The capacity to
generate strength in knee isokinetic dynamometry assessments correlates with jump performance. Strength imbalances from
one limb to another do not seem to interfere with jump performance. Strength imbalances between knee flexors and extensors
may be related to the functionality of volleyball players.
Rate of force development (RFD) refers to the ability of the neuromuscular system to increase contractile force from a low or resting level when muscle activation is performed as quickly as possible, and it is considered an important muscle strength parameter, especially for athletes in sports requiring high-speed actions. The assessment of RFD has been used for strength diagnosis, to monitor the effects of training interventions in both healthy populations and patients, discriminate high-level athletes from those of lower levels, evaluate the impairment in mechanical muscle function after acute bouts of eccentric muscle actions and to estimate the degree of fatigue and recovery after acute exhausting exercise. Notably, the evaluation of RFD in human skeletal muscle is a complex task since influenced by numerous distinct methodological factors including mode of contraction, type of instruction, method used to quantify RFD, devices used for force/torque recording and ambient temperature. Another important aspect is our limited understanding of the mechanisms underpinning rapid muscle force production. Therefore, this review is primarily focused on 1) describing the main mechanical characteristics of RFD; 2) analyzing various physiological factors that influence RFD; and 3) presenting and discussing central biomechanical and methodological factors affecting the measurement of RFD. The intention of this review is to provide more methodological and analytical coherency on the RFD concept, which may aid to clarify the thinking of coaches and sports scientists in this area.
Accentuated eccentric loading (AEL) prescribes eccentric load magnitude in excess of the concentric prescription using movements that require coupled eccentric and concentric actions, with minimal interruption to natural mechanics. This method has been theorized to potentiate concentric performance through higher eccentric loading and, thus, higher concentric force production. There is also evidence for favorable chronic adaptations, namely shifts to faster myosin heavy chain isoforms and changes in IIx-specific muscle cross-sectional area. However, research concerning the acute and chronic responses to AEL is inconclusive, likely due to inconsistencies in subjects, exercise selection, load prescription, and method of providing AEL. Therefore, the purpose of this review is to summarize: (1) the magnitudes and methods of AEL application; (2) the acute and chronic implications of AEL as a means to enhance force production; (3) the potential mechanisms by which AEL enhances acute and chronic performance; and (4) the limitations of current research and the potential for future study.
Although plyometric training (PT) improves change of direction (COD) ability, the influence of age on COD gains after PT is unclear. Therefore, the aim of this systematic review was to identify the age-related pattern of improvement in COD ability after PT in youths. A computerized search within six databases was performed, selecting studied based on specific inclusion criteria: experimental trials published in English-language journals, PT focused on the lower body, COD ability measurements reported before and after training, and male participants aged 10-to-18 years old. Sixteen articles with a total of 30 effect sizes (ESs) in the experimental groups and 13 ESs in the control groups were included. For the analyses, subjects were catagorized into three age groups: 10 to 12.9 years of age (PRE), 13 to 15.9 years of age (MID) and 16 to 18 years of age (POST). Independent of age, PT improved COD ability in youths (ES = 0.86, time gains [TG = -0.61]). However, a tendency toward greater COD ability gains was observed in older subjects (MID, ES = 0.95; POST, ES = 0.99) compared to younger subjects (PRE, ES = 0.68). Pearson product-moment correlation (r) indicated that 2-weekly sessions of PT induced meaningful COD ability gains (for ES, r = 0.436; for time gains, r = -0.624). A positive relationship was found between training intensity and ES (r = 0.493). In conclusion, PT improves COD ability in youths, with meaningfully greater effects in older youths. Two PT sessions per week, with 1400 moderate-intensity jumps for 7 weeks, seems to be an adequate dose.
This study compared the effects of unilateral and bilateral plyometric training on single and double-leg jumping performance, maximal strength and rate of force development (RFD). Fifteen moderately trained subjects were randomly assigned to either a unilateral (U, n=7) or bilateral group (B, n=8). Both groups performed maximal effort plyometric leg exercises two times per week for 6 weeks. The B group performed all exercises with both legs, while the U group performed half the repetitions with each leg, so that total exercise volume was the same. Jumping performance was assessed by countermovement jumps (CMJ) and drop jumps (DJ), while maximal isometric leg press strength and RFD were measured before and after training for each leg separately and both legs together. CMJ improvement with both legs was not significantly different between U (12.1±7.2%) and B (11.0±5.5%) groups. However, the sum of right and left leg CMJ only improved in the U group (19.0±7.1%, p<0.001) and was unchanged in the B group (3.4±8.4%, p=0.80). Maximal isometric leg press force with both legs was increased similarly between groups (B: 20.1±6.5%, U: 19.9±6.2%). However, the sum of right and left leg maximal force increased more in U compared to B group (23.8±9.1% vs. 11.9±6.2%, p=0.009, respectively). Similarly, the sum of right and left leg RFD0-50 and RFD0-100 were improved only in the U group (34-36%, p<0.01). Unilateral plyometric training was more effective at increasing both single and double-leg jumping performance, isometric leg press maximal force and RFD when compared to bilateral training.
This study examined power output on jumping and sprinting tests in young soccer players of differing pubertal status, while controlling for body size with allometric scaling exponents. A total of 46 males aged 12–18 years (14.17 years) were divided into three groups: pre-pubescent (n = 12), pubescent (n = 22), and post-pubescent (n = 12). Participants performed a series of tests, including the squat jump (SJ), countermovement jump (CMJ), and 10-meter and 30-meter sprint test protocols. The Post-PUB group was older (F = 112.411, p < 0.001), more experienced in competitive soccer (F = 8.055, p = 0.001), taller (F = 28.940, p < 0.001), and heavier (F = 20.618, p < 0.001), when compared to peers in the other groups. Mean differences in jumping and sprinting performances suggested a significant effect for pubertal status on performance in the 10-meter sprint (large effect size, F = 8.191, p < 0.001) and 30-meter sprint (large effect size, F = 8.093, p < 0.001) after allometric scaling. Power output derived from SJ (small effect size, F = 0.536, p = 0.001) and CMJ (small effect size, F = 1.058, p = 0.356) showed no significant differences across players of varying pubertal status. Biological maturation showed a large effect on maximal power output for sprints, but not for jumps, when the effect of body size was adjusted by statistically derived allometric exponents in young male soccer players.
This meta-analysis investigated the maturation-related pattern of adaptations to resistance training in boy athletes. We included studies examining the effects of 4–16-week resistance training programmes in healthy boy athletes aged 10–18 years. Pooled estimates of effect size for change in strength across all studies (n = 19) were calculated using the inverse–variance random effects model for meta-analyses. Estimates were also calculated for groups based on likely biological maturity status (“before”, “during” and “after” peak height velocity). Using the standardised mean difference, resistance training increased strength across all groups (effect size = 0.98, [CI: 0.70–1.27]). Strength gains were larger during (1.11 [0.67–1.54]) and after (1.01 [0.56–1.46]) peak height velocity than before (0.5 [−0.06–1.07]). Adaptations to resistance training are greater in adolescent boys during or after peak height velocity. These findings should help coaches to optimise the timing of training programmes that are designed to improve strength in boy athletes.
International Journal of Exercise Science 9(2): 149-158, 2016. This study examined the effects of a non-traditional training method, hypergravity training (HT), on anaerobic performance. Highly active men (n = 9) completed a 3 week HT protocol in which weighted vests were worn 8 h/day, 4+ days/week separate from training. Vest loads were 11.2 ± 0.6% of body mass during week one, and increased to 13.2 ± 0.7% (week 2), and 16.1 ± 0.4% (week 3). Performance testing included power clean 1-RM (PC), counter movement jumps, 4 continuous jumps, 36.6 m sprints (SP), a 137.2 m short shuttle run (SSR), and a 274.3 m long shuttle run (LSR). A 3 week non-hypergravity training period (NHT) proceeded HT. Baseline SP improved from 4.69 ± 0.29 s to 4.58 ± 0.22 s post-treatment, and regressed after NHT (4.69 ± 0.24 s) (p = 0.006, ES = 1.80). Improvements in SSR (p = 0.012, ES = 1.71) occurred from baseline (26.7 ± 1.5 s) to post-treatment (26.2 ± 1.4 s), followed by a return to near-baseline values (26.9 ± 1.8 s). Jumping tasks displayed similar trends, but no statistical differences and modest effect sizes (0.51-0.62) were found except for improved ground contact time during repeated jumps post-HT (ES = 2.26). PC and LSR performances did not improve. Three weeks of HT significantly enhanced short running task performances and decreased ground contact time between 4 continuous jumps. HT may be incorporated into training programs prior to key points in an athletic season without hindering the quality of regular training session activities.
The evaluation of rate of force development during rapid contractions has recently become quite popular for characterising explosive strength of athletes, elderly individuals and patients. The main aims of this narrative review are to describe the neuromuscular determinants of rate of force development and to discuss various methodological considerations inherent to its evaluation for research and clinical purposes. Rate of force development (1) seems to be mainly determined by the capacity to produce maximal voluntary activation in the early phase of an explosive contraction (first 50–75 ms), particularly as a result of increased motor unit discharge rate; (2) can be improved by both explosive-type and heavy-resistance strength training in different subject populations, mainly through an improvement in rapid muscle activation; (3) is quite difficult to evaluate in a valid and reliable way. Therefore, we provide evidence-based practical recommendations for rational quantification of rate of force development in both laboratory and clinical settings.
Objective: Numerous reports advocate that training of the proprioceptive sense is a viable behavioral therapy for improving impaired motor function. However, there is little agreement of what constitutes proprioceptive training and how effective it is. We therefore conducted a comprehensive, systematic review of the available literature in order to provide clarity to the notion of training the proprioceptive system.
Methods: Four major scientific databases were searched. The following criteria were subsequently applied: (1) A quantified pre- and post-treatment measure of proprioceptive function. (2) An intervention or training program believed to influence or enhance proprioceptive function. (3) Contained at least one form of treatment or outcome measure that is indicative of somatosensory function. From a total of 1284 articles, 51 studies fulfilled all criteria and were selected for further review.
Results: Overall, proprioceptive training resulted in an average improvement of 52% across all outcome measures. Applying muscle vibration above 30 Hz for longer durations (i.e., min vs. s) induced outcome improvements of up to 60%. Joint position and target reaching training consistently enhanced joint position sense (up to 109%) showing an average improvement of 48%. Cortical stroke was the most studied disease entity but no clear evidence indicated that proprioceptive training is differentially beneficial across the reported diseases.
Conclusions: There is converging evidence that proprioceptive training can yield meaningful improvements in somatosensory and sensorimotor function. However, there is a clear need for further work. Those forms of training utilizing both passive and active movements with and without visual feedback tended to be most beneficial. There is also initial evidence suggesting that proprioceptive training induces cortical reorganization, reinforcing the notion that proprioceptive training is a viable method for improving sensorimotor function.
Our aim was to compare the effects of 6-weeks of vertical, horizontal, or combined vertical and horizontal plyometric training on muscle explosive, endurance and balance performance. Forty young soccer players between 10 to 14 y of age were randomly divided into: control (CG; n = 10), vertical plyometric group (VG; n = 10), horizontal plyometric group (HG; n = 10) and combined vertical and horizontal plyometric group (VHG; n = 10). Players performance in the vertical (VCMJ) and horizontal (HCMJ) countermovement jump with arms, 5 multiple bounds test (MB5), 20 cm drop jump reactive strength index (RSI20), maximal kicking velocity (MKV),
sprint, change of direction speed (CODS), Yo-Yo intermittent recovery level 1 test (Yo-Yo IR1) and balance was measured. No significant or meaningful changes in the CG, apart from small change in the Yo-Yo IR1, were observed while all training programs resulted in meaningful changes in explosive, endurance and balance performance. However, only VHG showed a statistically significant (p<0.05) increase in all performance test and most meaningful training effect difference with the CG across tests. Although no significant differences in performance changes were observed between experimental groups, the VHG program was more effective
compared to VG (i.e. jumps, MKV, sprint, CODS and balance performance) and HG (i.e. sprint, CODS and balance performance) to small effect. The study demonstrated that vertical, horizontal and combined vertical and horizontal jumps induced meaningful improvement in explosive actions, balance and intermittent endurance capacity. However, combining vertical and horizontal drills seems more advantageous to induce greater performance improvements.
KEY WORDS: explosive strength; stretch-shortening cycle; team sports; childhood; strength
training.
The aim of the current review is to discuss applications and mechanism of eccentric exercise in training regimes of competitive sports. Eccentric muscle work is important in most sports. Eccentric muscle contractions enhance the performance during the concentric phase of stretch shortening cycles, which is important in disciplines like sprinting, jumping, throwing and running. Muscles activated during lengthening movements can also function as shock absorbers, to decelerate during landings tasks or to precisely deal with high external loading in sports like alpine skiing. Of the few studies available on trained subjects reveal that eccentric training can further enhance maximal muscle strength and power. It can further optimize muscle length for maximal tension development at a greater degree of extension, and has potential to improve muscle coordination during eccentric tasks. In skeletal muscles, these functional adaptations are based on increases in muscle mass, fascicles length, number of sarcomeres and cross sectional area of type II fibers. Identified modalities for eccentric loading in athletic populations involve classical isotonic exercises, accentuated jumping exercises, eccentric overloading exercises and eccentric cycle ergometry. We conclude that eccentric exercise offers a promising training modality to enhance performance and to prevent injuries in athletes. However, further research is necessary to better understand how the neuromuscular system adapts to eccentric loading in athletes.
This study investigated neuromuscular adaptations of the knee extensors after 8 weeks of plyometric training. 23 subjects were randomly assigned to an intervention group and a control group. We measured isometric maximum voluntary torque (iMVT), rate of torque development (RTD) and impulse (IMP) over different time intervals. The neural drive to muscles was estimated with the interpolated twitch technique and normalized root mean square of the EMG signal. Contractile properties, H reflexes as well as jump height in squat jump (SJ) and countermovement jump (CMJ) were evaluated. Neuromuscular testing was performed at 2 knee angles, i. e., 80° and 45° (0°=full extension). The iMVT at 80° knee flexion was 23.1 N · m (95% CI: 0.1-46.1 N · m, P=0.049) higher at post-test for the intervention group compared with controls. The same was true for RTD and IMP in the time interval 0-50 ms [308.7 N · m · s-1 (95% CI: 28.8-588.6 N · m · s-1, P=0.033) and 0.32 N · m · s (95% CI: 0.05-0.60 N · m · s, P=0.026), respectively]. These changes were accompanied by enhanced neural drive to the quadriceps muscle. Jump height in SJ and CMJ was higher at post-test for the intervention group compared with controls. Parameters at 45° knee flexion, contractile properties and evoked potentials did not differ between groups. Although hypertrophic changes were not measured, data suggest that the training regime probably induced mainly neural adaptations that were specifically related to the knee angle. The strength gains at 80° knee flexion likely contributed to the enhanced jump height in SJ and CMJ.
To investigate the selective effects of different types of external loads applied in vertical jump training on both the performance and muscle power output of the squat (SJ) and countermovement jump (CMJ).
Physically active males practiced maximum unconstrained vertical jumps over an 8-week period with no load, with either a negative or positive load exerted by a nearly constant external force that altered their body weight, and with a loaded vest that increased both the body weight and inertia. The magnitude of all applied loads corresponded to 30 % of body weight.
A similar training-associated increase in jump height was observed in all experimental groups in both CMJ (7.4-11.8 %) and SJ (6.4-14.1 %). The relative increase in power output was comparable to the increase in jump height in SJ (7.4-11.5 %), while the power increase in CMJ was relatively small and load-specific (0.5-9.5 %). The observed differences could originate from the changes in the CMJ pattern, reflected through the depth of the counter movement that particularly increased after the training with negative load (42 %) and no load (21 %). The same participants also revealed increased CMJ duration, reduced ground reaction forces, as well as reduced maximum and average power output when compared with other training groups.
Jump training with the applied loads could lead to a comparable improvement in jumping performance. However, the observed load-specific adaptations of CMJ pattern could decouple the training-associated increase in jump height from the increase in muscle power output.
The content of this manuscript is intended to assist the reader in collecting valid and reliable data for quantifying muscular strength and power. Various drawbacks and pitfalls of specific tests, as well as recommendations for the practitioner are also provided. The content is divided into sections covering isometric, isotonic, field tests, and isokinetic modes of exercise. Inherent in these modes are both concentric and eccentric muscle actions as well as both open and closed kinetic chain activities. For Isometric testing, contractions should occur over a four to five seconds duration with a one second transition period at the start of the contraction. At least one minute of rest should be provided between contractions. For each muscle tested at each position, at least three contractions should be performed although more may be performed if deemed necessary by the tester. For isotonic testing, the 1-RM test should be performed. After the general warm-up, the subject should perform a specific warm-up set of 8 repetitions at approximately 50% of the estimated 1-RM followed by another set of 3 repetitions at 70% of the estimated 1-RM. Subsequent lifts are single repetitions of progressively heavier weights until failure. Repeat until the 1-RM is determined to the desired level of precision. The rest interval between sets should be not less than one and not more than five minutes. The optimal number of single repetitions ranges from three to five. Data and guidelines of the following field tests are also provided; vertical jump, bench press, Wingate anaerobic cycle test (WAT), and the Margaria stair-run test. For isokinetic testing, details are provided for testing peak torque, work, power, endurance, and estimation of fiber type percentages.
The purpose of this study is to examine the effects of different volume and training surfaces during a short-term plyometric training program on neuromuscular performance. Twenty-nine subjects were randomly assigned to four groups: control group (CG, n=5), moderate volume group (MVG, n=9, 780 jumps), moderate volume hard surface group (MVGHS, n=8, 780 jumps), and high volume group (HVG, n=7, 1560 jumps). A series of tests were performed by the subjects before and after seven weeks of plyometric training. These tests were: measurement of maximum strength (5 maximum repetitions [5RM]), drop jumps (DJ) of varying height ( 20, 40, and 60cm), squat and countermovement jumps (SJ and CMJ, respectively), timed 20m sprint, agility, body weight, and height. The results of the present study suggest that high training volume leads to a significant increase in explosive performance that requires fast stretch shortening cycle (SSC) actions (such as DJ and sprint) in comparison to what is observed after a moderate training volume regimen. Secondly, when plyometric training is performed on a hard training surface (high impact reaction force), a moderate training volume induces optimal stimulus to increase explosive performance requiring fast SSC actions (e.g. DJ), maximal dynamic strength enhancement, and higher training efficiency. Thus, a finding of interest in the study was that after 7 weeks of plyometric training, performance enhancement in maximal strength and in actions requiring fast SSC (such as DJ and sprint) were dependent on the volume of training and the surface on which it was performed. This must be taken into account when using plyometric training on different surfaces.
Khlifa, R, Aouadi, R, Hermassi, S, Chelly, MS, Jlid, MC, Hbacha, H, and Castagna, C. Effects of a plyometric training program with and without added load on jumping ability in basketball players. J Strength Cond Res 24(11): 2955-2961, 2010-The purpose of this investigation was to examine the effect of a standard plyometric training protocol with or without added load in improving vertical jumping ability in male basketball players. Twenty-seven players were randomly assigned to 3 groups: a control group (no plyometric training), plyometric training group (PG), and loaded plyometric group (LPG, weighted vests 10-11% body mass). Before and after the 10-week training program, all the players were tested for the 5-jump test (5JT), the squat jump (SJ), and the countermovement jump (CMJ). The PG and LPG groups performed 2 and 3 training sessions per week, during the first 3 and the last 7 weeks, respectively. The results showed that SJ, CMJ, and 5JT were significantly improved only in the PG and LPG groups. The best effects for jumps were observed in LPG (p < 0.01), which showed significantly higher gains than the PG (p < 0.05). In conclusion, it appears that loads added to standard plyometric training program may result in greater vertical and horizontal-jump performances in basketball players.
Purpose:
The purpose of the present study was to investigate the relationship between weightlifting performance and the rate of force development (RFD), muscle architecture, and body composition in elite Olympic weightlifters.
Methods:
Six male Olympic weightlifters (age 23.3 [3.4] y, body mass 88.7 [10.2] kg, body height 1.76 [0.07] m, snatch 146.7 [15.4] kg, clean and jerk 179.4 [22.1] kg), all members of the national team, participated in the study. Athletes completed a 16-week periodized training program aiming to maximize their performance at the national competition event. Measurements, including maximal strength (1-repetition maximum) in snatch, clean and jerk, back and front squat, isometric leg press RFD and peak force, countermovement jump, vastus lateralis muscle architecture, and body composition, were performed before and after the training period.
Results:
Weightlifting performance increased significantly after training (P < .05). Leg press RFD increased only in time windows of 0 to 200 and 0 to 250 milliseconds after training (8.9% [8.5%] and 9.4% [7.7%], respectively, P < .05) while peak force remained unaltered (P < .05). Front squat strength increased significantly (P < .05), while countermovement jump power increased 2.3% (2.1%) (P < .05). No changes were observed for muscle architecture and lean body mass (P > .05). Significant correlations were observed between performance in snatch and clean and jerk with isometric leg press RFD, at all time windows, as well as with lean body mass and squat 1-repetition maximum.
Conclusions:
These results suggest that regular examination of RFD, lean body mass, and lower extremities' 1-repetition maximum may be useful performance predictors in elite Olympic weightlifters.
Radnor, JM, Oliver, JL, Waugh, CM, Myer, GD, and Lloyd, RS. Muscle Architecture and Maturation Influence Sprint and Jump Ability in Young Boys: A Multistudy Approach. J Strength Cond Res 36(10): 10.1519/JSC.0000000000003941-This series of experiments examined the influence of medial gastrocnemius (GM) and vastus lateralis (VL) muscle architecture (muscle thickness, pennation angle, and fascicle length) on sprint and jump performance in pre-, circa-, and post-peak height velocity (PHV) boys. In experiment 1, 1-way analysis of variance and Cohen's d effect sizes demonstrated that most muscle architecture measures were significantly greater in post-PHV compared with pre-PHV boys (d = 0.77-1.41; p < 0.05). For most sprint and jump variables, there were small to moderate differences between pre-PHV to circa-PHV and circa-PHV to post-PHV groups (d = 0.58-0.93; p < 0.05) and moderate to large differences between pre-PHV and post-PHV groups (d = 1.01-1.47; p < 0.05). Pearson's correlation analyses in experiment 2 determined that muscle architecture had small to moderate correlations with sprint and jump performance (r = 0.228-0.707, p < 0.05), with strongest associations within the post-PHV cohort. Chi-squared analyses in experiment 3 identified that, over 18 months, more POST-POST responders than expected made positive changes in GM and VL muscle thickness. Significantly more PRE-POST subjects than expected displayed changes in maximal sprint speed, while significantly more POST-POST individuals than expected showed positive changes in jump height. Muscle architecture seems to be larger in more mature boys compared with their less mature peers and likely underlies their greater performance in sprinting and jumping tasks. Boys experiencing, or having experienced, PHV make the largest increases in muscle architecture and sprinting and jumping performance when tracked over 18 months.
Soccer is a complex and exhaustive team-sport requiring a high level of tactical, technical, and physical ability to succeed. During a competitive match, a random combination of explosive and powerful activities, together with technical and tactical gestures, is performed in an intermittent manner over a 90-minute game. This review presents a detailed analysis and up-to-date synthesis of the literature describing activities and energy system contribution during soccer to provide to strength and conditioning coaches a clear understanding of soccer players' physical needs during competition.
Vertical force production (VFP) is widely recognized as a critical determinant of performance in a series of soccer-specific activities, such as sprinting, jumping, and changing direction. Therefore, practitioners are constantly seeking better and more effective strategies to improve VFP in professional soccer players. This article analyzes the mechanical aspects associated with the actual role played by VFP in elite soccer, and also examines and highlights the training considerations related to its appropriate and effective development during modern soccer seasons.
Purpose:
This study examined the effects of loaded (LPJT) and unloaded (UPJT) plyometric jump training programmes on measures of muscle power, speed, change-of-direction and kicking-distance performance in prepubertal male soccer players.
Methods:
Participants (N=29) were randomly assigned to a LPJT group (n=13; age=13.0±0.7 years) using weighted vests or UPJT group (n=16; age=13.0±0.5 years) using body mass only. Before and after the intervention, tests for the assessment of proxies of muscle power (i.e., countermovement-jump [CMJ], standing-long-jump [SLJ]), speed (i.e., 5-m, 10-m, and 20-m sprint), change-of-direction (i.e., Illinois change-of-direction test [ICoDT], modified 505 agility test), and kicking-distance test were conducted. Data were analysed using magnitude-based inferences.
Results:
Within-group analyses for the LPJT group showed large and very large improvements for 10-m sprint-time (effect size [ES]=2.00) and modified 505 CoD (ES=2.83) tests, respectively. For the same group, moderate improvements were observed in ICoDT (ES=0.61), 5- and 20-m sprint-time (ES=1.00 for both tests), CMJ (ES=1.00) and MKD (ES=0.90). Small enhancements in the SLJ (ES=0.50) test were apparent. Regarding the UPJT group, small improvements were observed for all tests (ES=0.33 to 0.57) except 5-m and 10-m sprint-time (ES=1.00 and 0.63, respectively). Between-group analyses favored the LPJT group for the modified 505 CoD (ES=0.61), SLJ (ES=0.50), and MKD (ES=0.57) tests, but not for 5-m sprint-time (ES=1.00). Only trivial between-group differences were shown for the remaining tests (ES=0.00 to 0.09).
Conclusion:
Overall, LPJT appears to be more effective than UPJT in improving measures of muscle power, speed, change-of-direction and kicking-distance performance in prepubertal male soccer players.
The purpose of this investigation was to examine the importance of strength and power in relation to key performance indicators (KPI's) within competitive soccer match play. This was achieved through using an experimental approach where fifteen subjects were recruited from a professional soccer club's scholarship squad during the 2013/14 season. Following anthropometric measures, power and strength were assessed across a range of tests which included the squat jump (SJ), countermovement jump (CMJ), 20 metre (m) sprint and arrowhead change of direction test. A predicted 1-repetition maximum (RM) was also obtained for strength by performing a 3RM test for both the back squat and bench press and a total score of athleticism (TSA) was provided by summing z-scores for all fitness tests together, providing one complete score for athleticism. Performance analysis data was collected during 16 matches for the following KPIs: passing, shooting, dribbling, tackling and heading. Alongside this, data concerning player ball involvements (touches) was recorded. Results showed that there was a significant correlation (p < 0.05) between CMJ (r = 0.80), SJ (r = 0.79) and TSA (r = 0.64) in relation to heading success. Similarly, a significant correlation (p < 0.05) between predicted 1RM squat strength and tackle success (r = 0.61). These data supports the notion that strength and power training are important to soccer performance, particularly when players are required to win duels of a physical nature. There were no other relationships found between the fitness data and the KPI's recorded during match play which may indicate that other aspects of player's development such as technical skill, cognitive function and sensory awareness are more important for soccer-specific performance.
This study examined the effect of 8-weeks of free-weight-resistance (RT) and plyometric (PLYO) training on maximal strength, explosiveness and jump performance compared with no added training (CON), in young male soccer players. Forty-one 11[FIGURE DASH]13-year-old soccer players were divided into three groups (RT, PLYO, CON). All participants completed isometric and dynamic (240°/s) knee extensions pre- and post-training. Peak torque (pT), peak rate of torque development (pRTD), electromechanical-delay (EMD), rate of muscle activation (Q50), m. vastus-lateralis thickness (VLT), and jump performance were examined. pT, pRTD and jump performance significantly improved in both training groups. Training resulted in significant (p<0.05) increases in isometric pT (23.4 vs. 15.8%) and pRTD (15.0 vs. 17.6%), in RT and PLYO, respectively. During dynamic contractions, training resulted in significant increases in pT (12.4 and 10.8% in RT and PLYO, respectively), but not pRTD. Jump performance increased in both training groups (RT=10.0%, PLYO=16.2%), with only PLYO significantly different from CON. Training resulted in significant increases in VLT (RT=6.7%. PLYO=8.1%). There were no significant EMD changes. In conclusion, 8-week free-weight resistance and plyometric training resulted in significant improvements in muscle strength and jump performance. Training resulted in similar muscle hypertrophy in the two training modes, with no clear differences in muscle performance. Plyometric training was more effective in improving jump performance, while free-weight resistance training was more advantageous in improving peak torque, where the stretch reflex was not involved.
Ullrich, B, Pelzer, T, and Pfeiffer, M. Neuromuscular effects to 6 weeks of loaded countermovement jumping with traditional and daily undulating periodization. J Strength Cond Res 32(3): 660-674, 2018-Loaded vertical jumps are routinely used to enhance athlete's power production in the lower extremity and to optimize jumping and sprinting performance. This study compared traditional (TP) and daily undulating (DUP) periodization on muscle strength, jumping performance, electromyographic (EMG) muscle activity, and muscle architecture during preseason loaded jump training. Twenty-two athletes from different team sports (age: 24.3 ± 2.6 years, height: 175.9 ± 7.5 cm, body mass: 72.2 ± 8.4 kg, 12 males/10 females, strength training experience: 5.1 ± 2.2 years) performed 6 weeks of loaded countermovement jumping (CMJ) (18 sessions) during which subjects arranged the experimental training loads with either TP or DUP. Therefore, loading conditions corresponding to 0, 15, and 30% of individual body mass were used by manipulating weighted training vests and the intensity zones and training volume were equated between the groups. Pre- to post-training, center of mass (COM) maximal CMJ performance, isometric maximal voluntary contractive capacity of the leg extensors (MVC), EMG maximal voluntary muscle activity of knee extensor muscles, and vastus lateralis and rectus femoris muscle architecture were examined. Repeated measures multivariate analysis of variances (MANOVA with factors: time × training group) revealed moderate (5-16%) but significant (p ≤ 0.006) temporal increases in COM jumping height, leg extensor MVC and muscle architecture in both groups. Importantly, these temporal alterations were similar using either TP or DUP. Therefore, our data indicate that both periodization models can be effectively applied to increase leg extensor strength, vertical jumping performance, and muscle architecture during short-term preseason loaded jump training.
The purpose of this study was to investigate the effect of different volumes of plyometric exercise (i.e., 100, 200, or 300 hurdle jumps) on acute strength and jump performance as well as on the acute hormonal and lactate responses in rugby players. Eleven young male elite rugby players (age, 23.5 ± 0.9 years; height, 173 ± 4.8 cm) volunteered for the study. Maximal isometric peak torque (PT), maximal rate of force development (RFD), and squat jump (SJ) and drop jump (DP) performance were assessed before and 5 minutes, 8 hours, and 24 hours after 100, 200, or 300 jumps. In addition, total testosterone, cortisol, and lactate were measure before and after the three different plyometric exercise volumes. There were significant decreases in the PT (P<0.02) and maximal RFD (P<0.001) 5 minutes, 8 hours, and 24 hours after 100, 200 and 300 jumps, with no differences between the exercise volumes. Additionally, there were significant decreases in the SJ (P<0.001) and DJ (P<0.01) performances 24 hours after 100, 200, and 300 jumps, with no differences between the exercise volumes. However, there were significant increases in the total testosterone (P<0.001), cortisol (P<0.05), and lactate (P<0.001) after 100, 200, and 300 jumps, with no differences between the exercise volumes. All plyometric exercise volumes (100, 200, and 300 jumps) resulted in similar neuromuscular, metabolic, and hormonal responses.