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This study aimed to investigate the kinematics and kinetics differences in ground reaction force (GRF)-time profiles with uni- and bimodal curves (UNC and BIC) during the concentric phase of the drop jump (DJ). Twenty two male Physical Education college student who met UNC (N = 11) or BIC (N = 11) of the GRF-time profile of were recruited. Two force plates and eight infrared optical cameras were synchronised to collect the GRF and motion data during DJ from a 30-cm height. The Shapiro-Wilk test was used to assess the normality of data. The Wilcoxon test was used when data were not normally distributed. Otherwise, Independent t-tests were used to compare differences between the UNC and BIC groups for each dependent variable. The UNC group demonstrated shorter ground contact time, lower jump height, greater leg stiffness, greater peak power during the eccentric phase, less work during the eccentric and concentric phases, and greater hip and knee joint flexion and extension angle displacements (p < 0.05). No significant intergroup differences were found in reactive strength index (p > 0.05). The UNC and BIC of the GRF-time profiles can indicate whether athletes can practice DJ appropriately. UNC can be representative of a better DJ performance with an efficient stretch-shortening cycle function. [ABSTRACT FROM AUTHOR]

The two-joint link model of mono- and biarticular muscles in human hindlimbs has been established on the basis of biomechanical and mechanical engineering analyses of electromyographic data and testing of the results using robotic hindlimbs equipped with mono- and/or biarticular actuators. The present review applies this model to the analysis of pedaling biomechanics and demonstrates its applicability to studies of human and non-human limb locomotion. Previously published three examples of electromyographic data on pedaling biomechanics are analyzed and reviewed in light of the two-joint link model. As comparable to published data on pedaling biomechanics, the results propose the essential parameters of the model, including activity switches and their directional changes, forces and their combined forces, all that occur in 360 degrees around the right ankle joint during the stationary and continuous pedaling activities. In addition, the co-activation of an antagonistic pair of biarticular muscles and parallel linkage function of a biarticular muscle are proposed to be tested further in both engineering and biological sciences. As biomimetics has contributed to engineering science, the models and/or hypotheses that would be generated in engineering science can be applied to biological science.

Introduction: The use of the jump as a plyometric exercise is a way to improve jump performance. Additionally, as it requires abrupt stopping, starting, and changing directions, it might enhance agility. Thus, this study aims to find out the relationship between drop jump variables and agility in contact sports. Materials and Methods: A total of 30 national-level male athletes (age=20.06±1.94 years; height=1.67±0.06 m; body weight: 58.02±8.40 kg) participated in this study. A drop jump test was performed on the Kistler force plate and agility was assessed by using the Illinois agility test along with the agility t-test. The Pearson correlation test was used to find the significant relationship between agility tests completion time and jump height from flight time, reactive strength index, average power, average force, and contact time for drop jumps. Results: The results indicate a significant moderate negative correlation between jump height from flight time and agility test time (r=-0.501 with Illinois agility test, P=0.005, and r=-0.601 with agility t-test, P=0.001). A significant weak negative correlation was observed between average power and Illinois agility test time (r=-0.477, P=0.008). Conclusion: These findings indicate that improved drop jumps will interpret better agility movements or vice versa; therefore, individuals who perform sports that require agile movement benefit from agility assessment and drop jump training. [ABSTRACT FROM AUTHOR]

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Purpose: This study aimed to examine the effects of plyometric jump training (PJT) on lower-limb stiffness. Methods: Systematic searches were conducted in PubMed, Web of Science, and Scopus. Study participants included healthy males and females who undertook a PJT programme isolated from any other training type. Results: There was a small effect size (ES) of PJT on lower-limb stiffness (ES = 0.33, 95% confidence interval (95%CI): 0.07–0.60, z = 2.47, p = 0.01). Untrained individuals exhibited a larger ES (ES = 0.46, 95%CI: 0.08–0.84, p = 0.02) than trained individuals (ES = 0.15, 95%CI: ‒0.23 to 0.53, p = 0.45). Interventions lasting a greater number of weeks (>7 weeks) had a larger ES (ES = 0.47, 95%CI: 0.06–0.88, p = 0.03) than those lasting fewer weeks (ES = 0.22, 95%CI: ‒0.12 to 0.55, p = 0.20). Programmes with ≤2 sessions per week exhibited a larger ES (ES = 0.39, 95%CI: 0.01–0.77, p = 0.04) than programmes that incorporated >2 sessions per week (ES = 0.20, 95%CI: –0.10 to 0.50, p = 0.18). Programmes with 500 jumps per week had negative effects (ES = –0.22, 95%CI: –1.10 to 0.67, p = 0.63). Programmes with >7.5 jumps per set showed larger effect sizes (ES = 0.55, 95%CI: 0.02–1.08, p = 0.04) than those with 7 weeks).

Vertical jumping performance is of high importance for various individual and team sports. Movement patterns utilizing a stretch shortening cycle are of particular interest. Despite their involvement in every vertical jump variation, the importance of the plantar flexors' dynamic maximum strength for jumping performance has not been investigated yet. Therefore, the aim of this study is to examine the relationship between plantar flexion strength and different vertical jump variations. The present study examines the correlation of maximum strength in the standing calf raise and in the squat with performance in the vertical jumping forms squat jump (SJ), countermovement jump (CMJ), and drop jump (DJ) from different heights in 56 physical education students. The one-repetition maximum (1 RM) in the standing calf raise shows moderate to high (p < 0.01) correlations for SJ and CMJ (r = 0.575–0.659, and r = 0.565–0.708, respectively). The DJ revealed weak to medium correlations (p < 0.01) with the dynamic maximum strength of the plantar flexors (r = 0.362–0.573). A comparison of the strongest and weakest subjects revealed significant differences between groups with the stronger participants displaying greater jumping performance in all tests. In addition, squat 1 RM was significantly correlated (p < 0.05) with DJ performance. It can be concluded that the strength of the plantar flexors displays a relevant factor for vertical jumping performance in SJ, CMJ, and DJ that supports the main propulsive mechanisms. [ABSTRACT FROM AUTHOR]

Our cross-sectional study aimed to investigate joint specificity of concentric muscle torque enhancement after a maximum eccentric contraction for the knee versus ankle joints across two different movement velocities (120°/s and 180°/s). After a familiarization session, 22 healthy young adults randomly performed concentric (CONC) and maximum eccentric preloaded concentric (EccCONC) muscle strength tests of the knee extensors and ankle plantar flexors of the non-dominant leg on an isokinetic strength testing device. We calculated the ratio between EccCONC and CONC (EccCONC/CONC) for all the conditions as the marker of concentric muscle torque enhancement. Separate two-way (joints x velocity) within repeated measures ANOVAs were used to determine joint-specific torque differences at 120°/s and 180°/s. CONC and EccCONC were greater for the knee extensors versus ankle plantar flexors at 120°/s and 180°/s (32.86%--102%; p < 0.001 for both); however, EccCONC/CONC was greater for the ankle plantar flexors than knee extensors at 120°/s (52.4%; p < 0.001) and 180°/s (41.9%; p < 0.001). There was a trend of greater EccCONC/CONC for the knee extensors at 180°/s than 120°/s (6.6%; p = 0.07). Our results show that greater concentric muscle torque enhancement after a maximal eccentric contraction occurs for the ankle plantar flexors versus knee extensors. Whether the joint- specificity of concentric muscle torque enhancement after a maximal eccentric contraction differentially affects sports performance is unknown. Our data provide a reference framework to investigate joint-specific concentric muscle torque enhancement for general and clinical athletic populations. [ABSTRACT FROM AUTHOR]

Introduction: The use of the jump as a plyometric exercise is a way to improve jump performance. Additionally, as it requires abrupt stopping, starting, and changing directions, it might enhance agility. Thus, this study aims to find out the relationship between drop jump variables and agility in contact sports. Materials and Methods: A total of 30 national-level male athletes (age=20.06±1.94 years; height=1.67±0.06 m; body weight: 58.02±8.40 kg) participated in this study. A drop jump test was performed on the Kistler force plate and agility was assessed by using the Illinois agility test along with the agility t-test. The Pearson correlation test was used to find the significant relationship between agility tests completion time and jump height from flight time, reactive strength index, average power, average force, and contact time for drop jumps. Results: The results indicate a significant moderate negative correlation between jump height from flight time and agility test time (r=-0.501 with Illinois agility test, P=0.005, and r=-0.601 with agility t-test, P=0.001). A significant weak negative correlation was observed between average power and Illinois agility test time (r=-0.477, P=0.008). Conclusion: These findings indicate that improved drop jumps will interpret better agility movements or vice versa; therefore, individuals who perform sports that require agile movement benefit from agility assessment and drop jump training.

PurposeThe aim of the study was to investigate the effects of a 10-week plyometric training (PT) on changes of direction, jumping ability, repeated sprint ability, and both muscular strength and power in youth female handball players.MethodsTwenty-eight participants (age: 15.8 ± 0.2 years) were randomly divided into a plyometric group (PG; n = 14) or a control group (CG; n = 14). Significant (group × time) interaction was noted for change of direction (COD) [Modified agility T-test (T-half)], three jumping tests [squat jump (SJ), countermovement jump (CMJ) and standing long jump (SLJ)], repeated sprint ability (RSA), muscular strength (1-RM bench press and 1-RM half squat) and muscular power (force-velocity test for both upper and lower limb).ResultsWith a group × time interaction, the PG enhanced the T-half performance [p

This study aimed to examine the effects of plyometric jump training (PJT) on lower-limb stiffness. Systematic searches were conducted in PubMed, Web of Science, and Scopus. Study participants included healthy males and females who undertook a PJT programme isolated from any other training type. There was a small effect size (ES) of PJT on lower-limb stiffness (ES = 0.33, 95% confidence interval (95%CI): 0.07–0.60, z = 2.47, p = 0.01). Untrained individuals exhibited a larger ES (ES = 0.46, 95%CI: 0.08–0.84, p = 0.02) than trained individuals (ES = 0.15, 95%CI: ‒0.23 to 0.53, p = 0.45). Interventions lasting a greater number of weeks (>7 weeks) had a larger ES (ES = 0.47, 95%CI: 0.06–0.88, p = 0.03) than those lasting fewer weeks (ES = 0.22, 95%CI: ‒0.12 to 0.55, p = 0.20). Programmes with ≤2 sessions per week exhibited a larger ES (ES = 0.39, 95%CI: 0.01–0.77, p = 0.04) than programmes that incorporated >2 sessions per week (ES = 0.20, 95%CI: –0.10 to 0.50, p = 0.18). Programmes with <250 jumps per week (ES = 0.50, 95%CI: 0.02–0.97, p = 0.04) showed a larger effect than programmes with 250–500 jumps per week (ES = 0.36, 95%CI: 0.00–0.72, p = 0.05). Programmes with >500 jumps per week had negative effects (ES = –0.22, 95%CI: –1.10 to 0.67, p = 0.63). Programmes with >7.5 jumps per set showed larger effect sizes (ES = 0.55, 95%CI: 0.02–1.08, p = 0.04) than those with <7.5 jumps per set (ES = 0.32, 95%CI: 0.01–0.62, p = 0.04). PJT enhances lower-body stiffness, which can be optimised with lower volumes (<250 jumps per week) over a relatively long period of time (>7 weeks). • Plyometric jump training can induce small, but statistically significant, increases in lower limb stiffness. • Plyometric jump training to enhance lower body stiffness can be optimised with lower volumes (<250 jumps per week) over a relatively long period of time (>7 weeks). • Stiffness adaptations appear to higher in untrained, compared to trained, participants. • To drive continued stiffness-related adaptations, coaches may have to place a greater emphasis on strain-inducing traditional resistance training than on plyometric jump training, in more advanced athletes. [Display omitted] [ABSTRACT FROM AUTHOR]

The aim of this study was to analyze the effects of a 5-week plyometric training added to the regular program of competitive young table tennis players on athletic performance compared to an active control group. Furthermore, connections between concentric and reactive leg power and a table tennis rating (TTR) were examined. Twenty-one table tennis players (10 male, 11 female) were assigned to a plyometric training group (PTG; n = 10) or control group (CG; n = 11). The additional training of PTG was integrated into their warmup procedures performed prior to table tennis training so that both groups completed similar training loads. At baseline and after training the following tests were conducted: squat jump (SJ), countermovement jump (CMJ), drop jumps (DJ) from 20 and 30 cm and change of direction speed (COD). For SJ and CMJ, the jumping height, for DJ, the reactive strength index, and for COD, total time were analyzed. After the intervention, the two-factor repeated measures analysis of variance (ANOVA) showed significant improvements for PTG in all parameters (6.8–18.0%) with small to moderate effect sizes. CG significantly improved SJ and COD (7.2–7.9%) with trivial to moderate ES. Significant interactions favoring PTG (group × time) occurred for SJ and CMJ. Furthermore, Pearson correlations showed significant relations to TTR for SJ (r = 0.531) and COD (r = −0.505). Additional plyometrics seem to improve jumping performance in pure concentric and slow stretch shortening cycle movements. Finally, SJ performance seems to be more important for table tennis players than CMJ and DJ performance. [ABSTRACT FROM AUTHOR]

Plyometric training on sand is suggested to result in advanced performance in vertical jumping. However, limited information exists concerning the biomechanics of drop jumps (DJ) on sand. The purpose of the study was to compare the biomechanical parameters of DJs executed on rigid (RIGID) and sand (SAND) surface. Sixteen high level male beach-volleyball players executed DJ from 40 cm on RIGID and SAND. Force- and video-recordings were analyzed to extract the kinetic and kinematic parameters of the DJ. Results of paired-samples t-tests revealed that DJ on SAND had significantly (p < 0.05) lower jumping height, peak vertical ground reaction force, power, peak leg stiffness and peak ankle flexion angular velocity than RIGID. In addition, DJ on SAND was characterized by significantly (p < 0.05) larger rate of force development and knee joint flexion in the downward phase. No differences (p > 0.05) were observed for the temporal parameters. The compliance of SAND decreases the efficiency of the mechanisms involved in the optimization of DJ performance. Nevertheless, SAND comprises an exercise surface with less loading during the eccentric phase of the DJ, thus it can be considered as a surface that can offer injury prevention under demands for large energy expenditure. [ABSTRACT FROM AUTHOR]

Abstract Background The effects of 7 weeks plyometric training on a stable surface and on sand were compared in junior male handball players. Methods A team of experienced players was divided randomly between three groups, undertaking a standard in-season regimen (C, n = 10), or supplementing this regimen by plyometric training on sand (PS, n = 11) or a stable surface (P, n = 10) for 7 weeks. Assessments included 20 m sprint times, change of direction tests (Modified change-of-direction T-test and Modified Illinois test), a repeated sprint T-test, jumping ability (squat, countermovement and five jump tests), and static and dynamic balance. Results After the intervention, PS showed significant increases of sprint speed relative to P and C. Change of direction scores were also improved for PS relative to P and C. Both PS and P increased vertical jump performance (squat jump, p = 0.005; ES = 0.170; counter-movement jump p P (p P). Conclusions We conclude that for reasons that remain to be clarified, several performance measures in adolescent male handball players were increased more by 7 weeks of PS than by P.

Anterior cruciate ligament (ACL) injuries are widespread, particularly in sports that involve rapid changes in direction, such as badminton, and it incapacitates an athlete severely and for a long time. ACL reconstruction followed by a structured rehabilitation program is essential for returning to peak performance. Plyometric training, known for enhancing explosive power and agility, is increasingly incorporated in post-ACL reconstruction rehabilitation for athletes. This case report presents the rehabilitation of a 19-year-old female badminton player operated for ACL reconstruction through the inculcation of plyometric training in the later phase to optimize better performance outcomes. The athlete demonstrated significant improvements in knee stability, strength, and functional performance. Plyometric exercises played a crucial role in restoring explosive power and agility, essential for competitive badminton, thereby facilitating a successful return to sport., Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Shedge et al.)

Plyometric exercises are a training stimulus that were developed in an attempt to bridge the gap between weight room muscular strength exercises and the speed or power needed on the track, field or court. Verkhoshansky (2018) uses physics to describe his method of plyometrics where a falling body creates kinetic energy which, upon impact with the ground, causes a high degree of muscle tension. The impact stimulates high threshold motor neurons and these, along with elastic energy, create the potential for an enhanced stretch shortening cycle with minimal amortization. This modality of training is a well-established method to improve vertical jumping ability (Adams et al., and Fatourous et al., 2000), and sprinting abilities as well (Miller 1980; Chu 1983), however, there still seems to be confusion surrounding its application. With most of the early research on plyometrics coming from Russia, a lot of the early information was lost in translation which lead to misapplication in the United States (Verkhoshansky, 2018). One clear example of this is in the execution of a drop jump versus a depth jump, and the appropriate height for each of these exercises (Verkhoshansky, 2018). The depth jump was typically performed on a 75cm box, with a larger countermovement, and an end goal of jumping as high as possible, while the drop jump typically used 30-45cm, landing with stiff legs and a minimal countermovement, sought to minimize ground contact times through the usage of elastic energy, while maximizing vertical displacement (Verkhoshansky, 2018). Researchers have shown that these exercises are capable of improving performance, but it has been hard to pinpoint the mechanism behind the adaptations. Vershoshansky (2018) indicated that when depth jumps are incorporated into a training cycle, they actually replace the heavy squat, yet at the end of the cycle his athletes’ squat maxes would increase. This would indicate that improved strength and force production could be a driving force behind the improvements in running speed and jumping abilities. Looking at this explanation, investigators might need to look at the neural aspects of movement including motor unit recruitment and increased muscle activation to find the process behind adaption and improved athletic performance as well as looking at the stretch-shortening cycle itself as the elastic energy minimizes the amortization phase. Verkhoshansky (1979) believed the neuromuscular system’s reaction to plyometric activity to be protective in nature and a result of either utilization of the stretch reflex, elastic energy recoil, or increased CNS activation due to rapid eccentric movements. If a more precise channel for what creates the adaptation is found it may allow for better programming which would not only enhance the adaptation but could lead to a reduction in injury. Therefore, the purpose of the review of literature is not to show that this modality of exercise can enhance athletic performance but, to gain an understanding on what mechanism drives the adaptation.

Plyometric training on sand is suggested to result in advanced performance in vertical jumping. However, limited information exists concerning the biomechanics of drop jumps (DJ) on sand. The purpose of the study was to compare the biomechanical parameters of DJs executed on rigid (RIGID) and sand (SAND) surface. Sixteen high level male beach-volleyball players executed DJ from 40 cm on RIGID and SAND. Force- and video-recordings were analyzed to extract the kinetic and kinematic parameters of the DJ. Results of paired-samples t-tests revealed that DJ on SAND had significantly (p < 0.05) lower jumping height, peak vertical ground reaction force, power, peak leg stiffness and peak ankle flexion angular velocity than RIGID. In addition, DJ on SAND was characterized by significantly (p < 0.05) larger rate of force development and knee joint flexion in the downward phase. No differences (p > 0.05) were observed for the temporal parameters. The compliance of SAND decreases the efficiency of the mechanisms involved in the optimization of DJ performance. Nevertheless, SAND comprises an exercise surface with less loading during the eccentric phase of the DJ, thus it can be considered as a surface that can offer injury prevention under demands for large energy expenditure.

Background: The effects of 7 weeks plyometric training on a stable surface and on sand were compared in junior male handball players. Methods: A team of experienced players was divided randomly between three groups, undertaking a standard in-season regimen (C, n = 10), or supplementing this regimen by plyometric training on sand (PS, n = 11) or a stable surface (P, n = 10) for 7 weeks. Assessments included 20 m sprint times, change of direction tests (Modified change-of-direction T-test and Modified Illinois test), a repeated sprint T-test, jumping ability (squat, countermovement and five jump tests), and static and dynamic balance. Results: After the intervention, PS showed significant increases of sprint speed relative to P and C. Change of direction scores were also improved for PS relative to P and C. Both PS and P increased vertical jump performance (squat jump, p = 0.005; ES = 0.170; counter-movement jump p < 0.001; ES = 0.247). Repeated sprint T-test scores improved in PS and P relative to C, with best times of PS > P (p < 0.05). Both plyometric groups improved their dynamic balance (p < 0.05), with three parameters of PS and only one of P being significantly greater than C. Static balance was also enhanced in both experimental groups (PS > P). Conclusions: We conclude that for reasons that remain to be clarified, several performance measures in adolescent male handball players were increased more by 7 weeks of PS than by P. [ABSTRACT FROM AUTHOR]

Introduction: Lawn tennis is one of the most admired racquet sports worldwide which is played either individually or in doubles. Circuit training is a simple method of giving a player a variety of exercises that will improve the three main functions i.e. speed, strength and agility, related to performance on the field. Plyometric training involves lengthening of muscle followed by quick shortening contraction that enhances capability of muscle to produce large amount of force. Aim: To compare the effectiveness of circuit training and plyometric training on speed, strength and agility in aspiring state level Lawn tennis players. Materials and Methods: The present study had an experimental study design. Forty male lawn tennis players in the age group of 18-25 years were included in this comparative study and randomly divided into two groups: Circuit training (Group A) and Plyometric training (Group B) with 20 players in each group. All players were evaluated for lower limb strength, upper limb strength, agility, running speed with Vertical Jump Test, Chest press test, agility-T-Test and 50 meter Dash test. Circuit training group performed 5 minutes warm up, 5 minutes sports specific training, Circuit training 28 to 42 minutes and cool down for 5 minutes. Plyometric group performed warm up 5 minutes, Plyometric training 30 to 60 minutes, 5 minutes sports specific training, cool down for 5 minutes. Paired t-test was used to compare the differences within the group and unpaired t-test was used to compare the difference between groups. Data was collected for all variables at baseline, 4th and end of 8th week. Results: Both groups improved significantly after 8th week but circuit training group showed highly significant difference for upper limb strength, lower limb strength, running speed and agility compared to plyometric training group (p

Fatigue and muscle damage negatively affect performance in lower limb exercises involving the stretch-shortening cycle in judo athletes during competition and training sessions. Photobiomodulation therapy has emerged as an effective non-invasive strategy to attenuate fatigue and muscle damage when applied before different types of exercises. Our objective was to investigate the effects of photobiomodulation therapy on fatigue and muscle damage in judo athletes. Sixteen judo athletes participated in the study (23.1 ± 3.8 years, 77.9 ± 14.9 kg, 173.1 ± 8.9 cm, 17.5 ± 7.3 body fat%, 12.9 ± 5.0 years of practice). Each participant received, in a randomized manner, photobiomodulation in one limb and placebo in the contralateral limb on the same day. Thereafter, subjects performed a stretch-shortening cycle protocol to induce muscle fatigue and damage. Countermovement jump (impulse, peak power, peak velocity, and peak force), echo intensity (rectus femoris and vastus lateralis), and muscle soreness were assessed at different time points before, during, immediately post, and 24 and 48 h after the protocol. Muscle fatigue was detected due to reductions in countermovement jump impulse (14.7 ± 9.8 and 15.9 ± 15.5%), peak power (12.9 ± 8.5 and 11.9 ± 6.9%), peak velocity (8.6 ± 8.1 and 6.5 ± 6.0%), and peak force (7.0 ± 5.3 and 8.0 ± 6.1%) after the protocol (p < 0.001), for placebo and photobiomodulation therapy, respectively. Muscle damage was detected due to reductions in countermovement jump impulse (−6.1 ± 19.2% and −4.5 ± 9.2%, p < 0.05), increases in echo intensity (rectus femoris, 21.0 ± 11.9 and 20.8 ± 9.0%; and vastus lateralis, 22.4 ± 23.2%; and 16.7 ± 23.8%; p < 0.001), and quadriceps muscle soreness (3.6 ± 1.6 and 3.5 ± 1.7 a.u; p < 0.011), 48 h after the protocol, for placebo and photobiomodulation therapy, respectively. No differences were observed between photobiomodulation therapy and placebo at any time points for any variables (p > 0.05), indicating no positive effect favoring photobiomodulation therapy. In conclusion, our findings suggest no effect of photobiomodulation therapy applied before exercise to reduce lower limb muscle fatigue and damage during and following a stretch-shortening cycle protocol in judo athletes.

Introduction: Lawn tennis is one of the most admired racquet sports worldwide which is played either individually or in doubles. Circuit training is a simple method of giving a player a variety of exercises that will improve the three main functions i.e. speed, strength and agility, related to performance on the field. Plyometric training involves lengthening of muscle followed by quick shortening contraction that enhances capability of muscle to produce large amount of force. Aim: To compare the effectiveness of circuit training and plyometric training on speed, strength and agility in aspiring state level Lawn tennis players. Materials and Methods: The present study had an experimental study design. Forty male lawn tennis players in the age group of 18-25 years were included in this comparative study and randomly divided into two groups: Circuit training (Group A) and Plyometric training (Group B) with 20 players in each group. All players were evaluated for lower limb strength, upper limb strength, agility, running speed with Vertical Jump Test, Chest press test, agility-T-Test and 50 meter Dash test. Circuit training group performed 5 minutes warm up, 5 minutes sports specific training, Circuit training 28 to 42 minutes and cool down for 5 minutes. Plyometric group performed warm up 5 minutes, Plyometric training 30 to 60 minutes, 5 minutes sports specific training, cool down for 5 minutes. Paired t-test was used to compare the differences within the group and unpaired t-test was used to compare the difference between groups. Data was collected for all variables at baseline, 4th and end of 8th week. Results: Both groups improved significantly after 8th week but circuit training group showed highly significant difference for upper limb strength, lower limb strength, running speed and agility compared to plyometric training group (p<0.05). Conclusion: Circuit training is an important method for improving upper limb and lower limb strength, running speed and agility in lawn tennis players. [ABSTRACT FROM AUTHOR]

This study aimed to examine the effects of adding whole-body vibration (WBV) within a realistic dynamic warm-up to potentiate reactive strength performance. Twelve highly-trained sprinters (8 males and 4 females, age: 22.6±2.6yr; stature: 1.68±0.08m; body mass: 62.4±11.2kg; competitive experience: 6.7±2.4yr) completed 2 experimental conditions: dynamic warm-up + WBV or dynamic warm-up alone (control: CON) in a balanced random, crossover manner. WBV was performed on a Power Plate Pro7 device (frequency: 40Hz, amplitude: 6mm) along with two exercises, 10 repetitions of squat and 10 repetitions of calf raise exercises during the first and second 30-s period, respectively of the total 60-s WBV exposure. For the CON, the same protocol was applied with the vibratory platform turned off. Reactive Strength Index (RSI) was obtained from a 35-cm height of drop jump at pre and 1-min post warm-up. The best (RSIbest) and mean (RSImean) values were analysed subsequently. The main effect of Time indicated an identical increase in WBV and CON for RSIbest (effect size (ES): 0.60; 14.5% difference; p=0.0005 and ES: 0.64; 16.0%; p=0.0005, respectively) and for RSImean (ES: 0.64; 16.0%; p=0.0005 and ES: 0.64; 16.0%; p=0.0005). There was no main effect (p>0.05) of Condition (between-group), and Condition*Time interaction. No statistical differences (p>0.05) were detected in magnitude of changes for WBV vs. CON in each sub-group, however, lower-level sprinters (n=6) responded better during WBV (6.1% and 5.7% increases in RSImean and RSIbest, respectively), while higher-level group did poorer (-4.6% and -5.5%). The data suggest that the effects of WBV exposure may depend on athlete's ability levels, maybe more beneficial to sub-elite but unnecessary for elite athletes. Collectively, a proper dynamic warm-up was sufficient to elicit positive effect on reactive strength performance. [ABSTRACT FROM AUTHOR]

The primary aim of this study was to assess the relationship between reactive and maximal strength measures with 40 m sprint performance and mechanical properties. Fourteen male and 14 female sprinters participated in this study. On the first day, subjects performed 40 m sprints with 10-m split times recorded in addition to maximal theoretical velocity, maximal theoretical force and peak horizontal power, which were calculated from force-velocity relationships. On the second day, subjects performed isometric midthigh pulls (IMTPs) with peak force (PF) and relative PF calculated, drop jumps (DJs) and vertical hopping where the reactive strength index (RSI) was calculated as jump height (JH) divided by contact time (CT). Pearson correlations were used to assess the relationships between measures and independent samples t -tests were used to assess the differences between men and women. No significant correlations were found between DJ and hopping RSI and sprint measures. A significant strong positive correlation was found between IMTP PF and peak horizontal power in men only ( r = 0.61). The male sprinters performed significantly better in all recorded measures apart from hopping (CT, JH and RSI) and DJ CT where no significant differences were found. The lack of association between reactive and maximal strength measures with sprint performance is potentially because of the test's prolonged CTs relative to sprinting and the inability to assess the technical application of force. Several methods of assessing reactive strength are needed that can better represent the demands of the distinct phases of sprinting e.g., acceleration, maximum velocity. [ABSTRACT FROM AUTHOR]

This research aims to provide data on explosive and reactive strength characteristics of Italian elite Trials athletes, through vertical jump tests. Five elite athletes (age: 19.6±3.3 y; height: 1.80±0.04 m; body mass: 71.7±7.4 kg) all participating in the Trials World Cup, performed the squat jump and the countermovement jump tests. The height of the jumps was measured using the OptoJump Next (Microgate, Bolzano, Italy). The height of the jump was obtained, then the eccentric utilization ratio (EUR) was calculated as a ratio between the heights of CMJ and SJ, mean and standard deviation of the sample were obtained through a descriptive statistical analysis. Furthermore, a comparison was made between the values obtained and values found in the scientific literature for elite athletes from other sports. From research carried out exclusively data on high-level athletes and performed with OptoJump technology were collected, all studies not corresponding to these criteria were excluded from the analysis. The results show that the Italian elite Trials athletes have good explosive and reactive strength as shown in the SJ (41.0 ± 2.4cm) and in the CMJ (44.0 ± 4.5cm), they also display good performance in comparison to athletes of the same level in other sports, similar to those of hurdlers and volleyball players, also the EUR above 1 (1.07 ± 0.5) suggests that they are well-trained athletes. The results obtained, although on a small sample, provide useful data to describe the athletic profile of Italian elite Trials athletes and could help coaches to structure training programs adapted to the specific demands of this sport. [ABSTRACT FROM AUTHOR]

The level of performance in high speed sprint running is result-relevant in track and field events and in team sports. Correlation coefficients between maximal force production of the extensor chain of the lower extremities - mostly tested via one repetition maximum (1RM) in a squat - and sprinting performance have been frequently reported. However, correlations of dynamic maximal force production of the plantar flexors and sprints have yet to be reported. Assuming that with increasing distance the stretch-shortening-cycle, which is dominated by reflex mechanisms gains importance, a decrease of the influence of the maximum force for the calf muscles is conceivable. Fifty-six physical education students (40 male, 16 female) participated in the present study. Maximum strength in the standing barbell calf raise and sprint performance over 30 m were obtained on different days separated by one week. The study provides correlation coefficients of 1RM of plantar flexors and sprinting performance in sections up to 30 m. Therefore, sprint performance for sections 0-5, 0-10, 0-15, 0-20, 0-25 and 0-30 m were determined. The results show medium to strong, consistently significant correlations (p < 0.01) both, for the absolute (r = -0.483 to -0.675) and the relative maximum force (r = -0.460 to -0.547). [ABSTRACT FROM AUTHOR]

Fatigue and muscle damage negatively affect performance in lower limb exercises involving the stretch-shortening cycle in judo athletes during competition and training sessions. Photobiomodulation therapy has emerged as an effective non-invasive strategy to attenuate fatigue and muscle damage when applied before different types of exercises. Our objective was to investigate the effects of photobiomodulation therapy on fatigue and muscle damage in judo athletes. Sixteen judo athletes participated in the study (23.1 ± 3.8 years, 77.9 ± 14.9 kg, 173.1 ± 8.9 cm, 17.5 ± 7.3 body fat%, 12.9 ± 5.0 years of practice). Each participant received, in a randomized manner, photobiomodulation in one limb and placebo in the contralateral limb on the same day. Thereafter, subjects performed a stretch-shortening cycle protocol to induce muscle fatigue and damage. Countermovement jump (impulse, peak power, peak velocity, and peak force), echo intensity (rectus femoris and vastus lateralis), and muscle soreness were assessed at different time points before, during, immediately post, and 24 and 48 h after the protocol. Muscle fatigue was detected due to reductions in countermovement jump impulse (14.7 ± 9.8 and 15.9 ± 15.5%), peak power (12.9 ± 8.5 and 11.9 ± 6.9%), peak velocity (8.6 ± 8.1 and 6.5 ± 6.0%), and peak force (7.0 ± 5.3 and 8.0 ± 6.1%) after the protocol (p < 0.001), for placebo and photobiomodulation therapy, respectively. Muscle damage was detected due to reductions in countermovement jump impulse (−6.1 ± 19.2% and −4.5 ± 9.2%, p < 0.05), increases in echo intensity (rectus femoris , 21.0 ± 11.9 and 20.8 ± 9.0%; and vastus lateralis , 22.4 ± 23.2%; and 16.7 ± 23.8%; p < 0.001), and quadriceps muscle soreness (3.6 ± 1.6 and 3.5 ± 1.7 a.u; p < 0.011), 48 h after the protocol, for placebo and photobiomodulation therapy, respectively. No differences were observed between photobiomodulation therapy and placebo at any time points for any variables (p > 0.05), indicating no positive effect favoring photobiomodulation therapy. In conclusion, our findings suggest no effect of photobiomodulation therapy applied before exercise to reduce lower limb muscle fatigue and damage during and following a stretch-shortening cycle protocol in judo athletes. [ABSTRACT FROM AUTHOR]

Plyometric training performed at sea level enhance explosive and endurance performance at sea level. However, its effects on explosive and endurance performance at high altitude had not been studied. Therefore, the aim of this study was to determine the effects of a sea level short-term (i.e., 4-week) plyometric training program on explosive and endurance performance at sea level and at high altitude (i.e., 3,270 m above sea level). Participants were randomly assigned to a control group (n = 12) and a plyometric training group (n = 11). Neuromuscular (reactive strength index - RSI) and endurance (2-km time-trial; running economy [RE]; maximal oxygen uptake - VO2max) measurements were performed at sea level before, at sea level after intervention (SL +4 week), and at high altitude 24-h post SL +4 week. The ANOVA revealed that at SL +4 week the VO2max was not significantly changed in any group, although RE, RSI and 2-km time trial were significantly (p < 0.05) improved in the plyometric training group. After training, when both groups were exposed to high altitude, participants from the plyometric training group showed a greater RSI (p < 0.05) and were able to maintain their 2-km time trial (11.3 ± 0.5 min vs. 10.7 ± 0.6 min) compared to their pre-training sea level performance. In contrast, the control group showed no improvement in RSI, with a worse 2-km time trial performance (10.3 ± 0.8 min vs. 9.02 ± 0.64 min; p < 0.05; ES = 0.13). Moreover, after training, both at sea level and at high altitude the plyometric training group demonstrated a greater (p < 0.05) RSI and 2-km time trial performance compared to the control group. The oxygen saturation was significantly decreased after acute exposure to high altitude in the two groups (p < 0.05). These results confirm the beneficial effects of sea level short-term plyometric training on explosive and endurance performance at sea level. Moreover, current results indicates that plyometric training may also be of value for endurance athletes performing after an acute exposure to high altitude. [ABSTRACT FROM AUTHOR]

Speed is a crucial aspect in softball, and can be the difference between winning and losing. Base stealing is a method used to produce runs. There has been debate over which starting position is the most advantageous to maximize acceleration and speed to reach the next base the fastest. The purpose of this study was to examine the effect of different starting stances on acceleration and speed phases in collegiate softball players. Seventeen healthy NCAA Division I women's softball players (age = 19.9 ± 1.3yrs, height = 167.0 ± 5.4cm, mass = 74.8 ± 14.1kg) volunteered to participate. Three maximum 45 ft sprints, with one minute rest, were performed (with splits at 15, 30 and 45ft) for each of three starting stances (front foot on the base, back foot on the base, and cross over stance). A 1x3 repeated measures ANOVA for total time demonstrated that front foot on the base was significantly faster (2.51 ± 0.18s) than back foot on the base (2.70 ± 0.19s) and the cross over step (2.66 ± 0.23s). For all three splits, front foot on the base was also significantly faster (0.96 ± 0.07s, 0.81 ± 0.06s, and 0.73 ± 0.06s) than back foot on the base (1.10 ± 0.13s, 0.84 ± 0.05s, and 0.75 ± 0.43s) and cross over step (1.04 ± 0.09s, 0.84 ± 0.06s, and 0.75 ± 0.07s). The decrease in time for front foot on the base was probably the result of using the base to push against, like a sprinter's block, to produce greater horizontal force to accelerate faster and reach a greater top speed. Coaches should teach their softball athletes to stand with their front foot on the base when base running. [ABSTRACT FROM AUTHOR]

Our purpose was to evaluate the vertical ground reaction force, impulse, moments and powers of hip, knee and ankle joints, contact time, and jump height when performing a drop jump from different drop heights based on the percentage of a performer's maximum vertical jump height (MVJH). Fifteen male Division III athletes participated voluntarily. Eleven synchronized cameras and two force platforms were used to collect data. One-way repeated-measures analysis of variance tests were used to examine the differences between drop heights. The maximum hip, knee and ankle power absorption during 125 %MVJH and 150 %MVJH were greater than those during 75 %MVJH. The impulse during landing at 100 %MVJH, 125 %MVJH and 150 %MVJH were greater than 75 %MVJH. The vertical ground reaction force during 150 %MVJH was greater than 50 %MVJH, 75 %MVJH and 100 %MVJH. Drop height below 75 %MVJH had the most merits for increasing joint power output while having a lower impact force, impulse and joint power absorption. Drop height of 150 %MVJH may not be desirable as a high-intensity stimulus due to the much greater impact force, increasing the risk of injury, without increasing jump height performance. [ABSTRACT FROM AUTHOR]

Purpose: The aim of the study was to investigate the effects of a 10-week plyometric training (PT) on changes of direction, jumping ability, repeated sprint ability, and both muscular strength and power in youth female handball players., Methods: Twenty-eight participants (age: 15.8 ± 0.2 years) were randomly divided into a plyometric group (PG; n  = 14) or a control group (CG; n  = 14). Significant (group × time) interaction was noted for change of direction (COD) [Modified agility T -test (T-half)], three jumping tests [squat jump (SJ), countermovement jump (CMJ) and standing long jump (SLJ)], repeated sprint ability (RSA), muscular strength (1-RM bench press and 1-RM half squat) and muscular power (force-velocity test for both upper and lower limb)., Results: With a group × time interaction, the PG enhanced the T-half performance [ p  < 0.001, Δ = 10.4, d  = 1.95 (large)] compared to the CG. The PG enhanced the jump performance over SJ [ p  = 0.009, Δ = 18.3, d  = 0.72 (medium)], CMJ [ p  = 0.005, Δ = 20.7, d  = 0.79 (medium)] and SLJ [ p  < 0.001, Δ = 24.5, d  = 2.25 (large)]. Three of four RSA scores increased significantly in the PG compared to the CG [ p  < 0.001, Δ = 2.76, d  = 1.11 (large); p  < 0.001, Δ = 2.72, d  = 1.23 (large); and p  < 0.001, Δ = 2.75, d  = 1.21 (large), in best time (RSA-BT), mean time (RSA-MT) and total time (RSA-TT), respectively]. In contrast, group × time interactions revealed no significant differences in both 1-RM bench press and 1-RM half squat performance between PG and CG. Regarding the force velocity performance, the PG enhanced 3 of 4 force velocity scores for the upper limb performance [ p  < 0.001, d  = 1 (large); p  < 0.001, d  = 1.13 (large) and p  = 0.012, d  = 0.72 (medium) for the peak power in these two forms (W and W·kg-1), and maximal pedalling velocity, respectively], and 2 of 4 force velocity scores for the lower limb performance [ p  = 0.045, d  = 0.56 (medium); and p  = 0.021, d  = 0.65 (medium) for the peak power in these two forms (W and W·kg-1), respectively]., Conclusion: It was concluded that additional PT performed two times per week during 10 weeks enhances measures related to game performance, such as COD, jump ability, RSA, and power in youth female handball players., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2023 Gaamouri, Hammami, Cherni, Rosemann, Knechtle, Chelly and van den Tillaar.)