Countermovement Jump Research Articles

The Effects of Low-Load Squat Jump and Maximal Isometric Priming Exercise on Muscular Performance and Perceptual State.

Harrison, PW, James, LP, Jenkins, DG, McGuigan, MR, Holmberg, PM, and Kelly, VG. The effects of low-load squat jump and maximal isometric priming exercise on muscular performance and perceptual state. J Strength Cond Res 38(1): 1-9, 2024-The aim of this study was to examine responses at 3 and 27 hours after low-load jump squat (LL) and maximal isometric half-squat (ISO) priming stimuli. Fifteen resistance-trained males performed LL (4 × 3 at 20% 1 repetition maximum [1RM]), ISO (4 × 3 seconds), and control (CON) activities (standardized warm-up) in a randomized and counterbalanced order. Countermovement jump (CMJ) and isometric midthigh pull tests were conducted to assess performance changes after priming and CON activities. No clear changes in CMJ measures were found after priming activities compared with CON. However, small effect size improvements were found after priming stimuli completed on the same day. A 2.9% decrease in concentric phase duration (CI = 0.3-5.9, p = 0.333, Cliff's delta = -0.156) and a 9.1% increase in RSImod (CI = 0.2-12.3, p = 0.151, Cliff's delta = -0.218) occurred at 3 hours after LL compared with CON. Braking phase duration (CI = 0.8-10.6, p = 0.333, Cliff's delta = -0.213) was 2.9% shorter at 3 hours after ISO compared with CON. No clear changes in isometric peak force occurred after priming activities compared with CON. Additionally, questionnaires were completed to assess perceptual state and perceived effectiveness of the priming stimulus to influence performance. An increase in the "effect of activity" was perceived at 3 hours after LL and ISO (p = 0.013-0.044, Cliff's delta = 0.578-0.6) and at 27 hours after ISO (p = 0.99, Cliff's delta = 0.173) compared with CON. An increase in "muscular heaviness" was also reported at 3 hours after ISO compared with CON (p = 0.199, Cliff's delta = 0.320). The collective findings suggest limited benefits over the day after LL and ISO priming stimuli. However, as there was substantial variation in individual responses, the relative nature of priming responses should be considered when prescribing similar strategies in practical environments.

Clinical implications of Squat Jump and Countermovement Jump among young females of United Arab Emirates : Comparative Biomechanical Analysis

Clinical implications of Squat Jump and Countermovement Jump among young females of United Arab Emirates : Comparative Biomechanical Analysis

Effects of Repeated Jump Testing and Diurnal Changes on Subsequent Countermovement Jump and Squat Jump Output and Force-Time Characteristics

Abstract Harrison, PW, James, LP, Jenkins, DG, Holmberg, PM, and Kelly, VG. Effects of repeated jump testing and diurnal changes on subsequent countermovement jump and squat jump output and force-time characteristics. J Strength Cond Res 38(1): 174–179, 2024—The aim of this brief study was to investigate the effects of repeated jump testing on performance over 2 consecutive days while considering the possibility of diurnal changes. Fourteen male subjects and 14 recreationally active female subjects completed countermovement jump (CMJ) and squat jump (SJ) testing on 5 occasions (baseline [0,800], 5 minutes [0,820], 8 hours [1,600], 24 hours [0,800], and 32 hours [1,600]) over 32 hours. An additional rested baseline test was conducted on a separate day in the afternoon (1,600) to compare jump performance between morning and afternoon baseline values. Excluding small decreases in CMJ height at 24 hours (p = 0.292, Cliff’s delta = −0.225) in male subjects and similar decreases in CMJ height at 5 minutes (p = 0.034, Cliff’s delta = −0.245) in addition to SJ height:contraction time at 32 hours (p = 0.126, Cliff’s delta = 0.153) in female subjects, findings generally showed no changes in jump performance over multiple assessments. Squat jump metrics may have showed small improvements between morning and afternoon baseline values in male subjects (SJ height:contraction time [p = 0.030, Cliff’s delta = 0.225]) and female subjects (SJ height [p = 0.013, Cliff’s delta = 0.173] and SJ height:contraction time [p = 0.091, Cliff’s delta = 0.163)]. As jump performance was largely unaffected by repeated jump testing, the present findings support the use of monitoring practices and research designs that require multiple jump assessments within acute periods (∼32 hours).

Integrating Resistance Training Into Secondary School Physical Education Lessons: Effects of a 6-Week Intervention on Athletic Motor Skill Competencies.

The purpose of this study was to examine the effects of resistance training (RT) in physical education lessons on athletic motor skill competencies in secondary school children. Seventy-eight males were randomized into experimental year groups or a control group. Experimental groups participated in RT during physical education lessons for a 6-week half-term. The control group continued with their games-based curriculum. Countermovement jump (CMJ) height, seated medicine ball throw (SMBT) distance, and RT skills battery scores were measured preintervention and postintervention. All experimental groups significantly improved SMBT distance and RT skills quotient (P < .05). All intervention year groups also significantly improved CMJ height (P < .05), except for year 9. Although the control group did not show improvements in CMJ height and RT skills quotient, there was a significant improvement in SMBT distance (P < .05). The year 7 and 8 males exhibited greater improvements in CMJ height and SMBT distance (d = 0.21-0.79) than in year 9 (d = 0.00-0.40). Results of the study indicated that a 6-week half-term RT intervention in physical education lessons can improve athletic motor skill competencies (P < .05, d = 0.21-2.51) in male youths.

Effects of light- vs. heavy-load squat training on velocity, strength, power, and total mechanical work in recreationally trained men and women.

The purpose of this study was to investigate the effects of light and heavy loads in the squat exercise on kinematics and mechanical variables in recreationally trained men and women. Twenty-two men and sixteen women were assigned to 4 groups: 40% and 80% one-repetition maximum (1RM) male (M40 and M80) and female (F40 and F80). Over 6 weeks, participants performed twice a week the full back-squat (SQ) exercise with initially equated relative volume load (Sets*Repetitions/Set*%1RM). All groups performed different amounts of work (p < 0.05), while relative work (work/1RM) only differed between load groups (p < 0.001). There was no significant Time*Sex*Load interaction. Based on the magnitude of effect sizes: M80 achieved small improvements in the SQ maximum isometric force (MIF; ES = 0.43, 95% CI [0.16, 0.81]); small gains in squat estimated 1RM strength were observed in the 80%-1RM groups (M80: 0.42 [0.18, 0.77]; F80: 0.44 [0.26, 0.76]) and the F40 group (0.42 [0.17, 0.81]); all groups made moderate to large gains in the average velocity attained against heavy loads (> 60%1RM; F40: 1.20 [0.52, 2.27]; F80: 2.20 [1.23, 3.93]; M40: 0.85 [0.29, 1.59]; M80: 1.03 [0.55, 1.77]), as well as small to moderate improvements in the average velocity against light loads (< 60%1RM; F40: 0.49[-0.24, 1.68]; F80: 1.10 [0.06, 3.16]; M40: 0.80 [0.41, 1.35]; M80: 0.93 [0.25, 1.84]). Lastly, only the F40 group showed small improvements in countermovement jump (CMJ) height (ES = 0.65 [0.14, 1.37]). In conclusion, light and heavy loads produced similar strength gains in men and women when initially equated by relative volume load, although the standardized mean differences suggest nuances depending on the sample and task.

Limb-belt resisted sprint training improves physical fitness and ball-throw velocity in pubertal handball players.

The study assessed the effect of six weeks of biweekly upper and lower limbs' weighted-belt resisted sprint training (BRST) and weighted-vest resisted sprint training (VRST), or normal sprint training (NST) on muscle strength, speed, change of direction and handball-throwing velocity in young handball players. Twenty-seven pubertal male handball players aged 14.4 years were randomly assigned into BRST (n = 9), VRST (n = 8), and NST (n = 8) groups. Sprint ability (10-m and 30-m), squat jump (SJ), countermovement jump (CMJ), free-arm countermovement jump (CMJFA), standing long jump (SLJ), Five-jump test (FJT), change of direction and handball-throw velocity were assessed before and after a 6-week training in-season program. Within-group interactions showed that BRST improved all tests' performances (moderate-to-large). VRST improved sprint, SLJ, FJT and handball-throw velocity performances (small-to-large). NST improved only the change of direction performances (moderate). Between-groups comparison revealed that BRST improved all testing performances, except change of direction, compared with NST (large) and improved 30-m sprint, CMJFA, FJT and handball-throw velocity performance compared with VRST (moderate-to-large). In addition, VRST improved 30-m sprint, SJ and handball-throw velocity performances compared with NST (moderate-to-large). Throwing performance changes correlated with changes in sprint time and horizontal and vertical jump abilities (r = 0.40 to r = 0.69; p < 0.01). We conclude that while both resisted sprint training improved players' sprint, jumping and handball-throw performances, substantial improvements were recorded with the BRST compared to VRST and NST. Thus, BRST could be recommended to male U15 handball players as a valuable training method for developing physical fitness and skill performances.

Effects of plyometric-based structured game active breaks on fundamental movement skills, muscular fitness, self-perception, and actual behaviour in primary school students.

This study examined the effects of plyometric-based structured game active breaks on fundamental movement skills (FMS), muscular fitness, student self-perception, and teacher's rating of actual behaviour in Grade 3 and 4 students. Primary school children aged 8-10 years old, from four classes, were cluster-randomly assigned to an intervention group (IG) (n = 54) or a control group (CG) (n = 48). The IG participated in structured plyometric-based game active breaks for 7-10 minutes daily, for six consecutive weeks. The CG resumed their regular daily school routine. FMS were assessed with the Canadian Agility Movement Skills Assessment test, and muscular fitness with the standing long jump (SLJ), countermovement jump (CMJ), and seated medicine ball chest throw tests. The Self-Perception Profile for Children and the Teacher's Rating Scale of Child's Actual Behaviour assessed student self-perception and teacher's perception of student actual behaviour, respectively. A significant (p < 0.01) interaction group by time was observed, with greater improvements in the IG compared to the CG in FMS (%diff = 13.11, ƞp2 = 0.12), SLJ (%diff = 6.67, ƞp2 = 0.02), seated medicine ball chest throw (%diff = 4.69, ƞp2 = 0.08), student social self-perception (%diff = 9.31, ƞp2 = 0.10), student scholastic self-perception (%diff = 7.27, ƞp2 = 0.10), and teacher perception of student social competence (%diff = 8.31, ƞp2 = 0.05). No difference (p > 0.05) was found in other variables. Integrating plyometric-based structured game active breaks into primary school settings evidenced improvement in FMS, muscular fitness, student self-perception, and teacher's rating of student actual behaviour.

Effects of Training With Different Hang-Power-Clean Intensities on the Maximum Dynamic Strength, Vertical Jump, and Sprint Performance of Female Handball Players.

To compare the effects of 7weeks of training with different hang-power-clean (HPC) intensities on the maximum dynamic strength, vertical jump, and sprint performance of female handball players. Professional handball athletes with at least 1year of HPC experience volunteered to participate. The athletes were balanced by position and randomly assigned to a group with HPC at 90% (HPC90%) or 50% (HPC50%) of HPC 1-repetition maximum (1RM). The training volume was equalized between groups. Pretraining and posttraining assessments included 1RM HPC, jump height in the squat jump (SJ) and countermovement jump(CMJ), and sprint speeds at 5, 20, and 30m. From pretraining to posttraining, both groups significantly increased (P ≤ .05) 1RM HPC, although a small effect size was observed in favor of HPC90%. HPC90% and HPC50% did not induce significant changes (P > .05) in the SJ and CMJ height, although for the SJ, a small effect size was observed in favor of HPC90%. Both groups induced a significant improvement (P ≤ .05) in 5-, 20-, and 30-m sprint speeds, although for all speeds, small to moderate effect sizes were observed in favor of HPC90%. Both training groups induced significant improvements in 1RM HPC and sprint speeds, whereas no significant changes were observed in vertical jumps. In addition, based mainly on the effect sizes, the HPC90% group was more effective for increasing 1RM HPC, SJ, and sprint speeds than the HPC50% group.

Effect of Combined Feedback and Verbal Encouragement on Anaerobic Performance, Technical and Physiological Aspects During Small-Sided Basketball Games for Students’ Girls

Objective: The aim of this research is to determine the effect of combined feedback and verbal encouragement on anaerobic performance, technical and physiological aspects during small-sided Basketball games for adolescent schoolgirls. Material and Methods: Sixty schoolgirls were divided into 3 groups of 20 girls: control group (G1) (mean ± standard deviation (M±SD); age:15.45 ± 0.41years), verbal encouragement group (G2) (M±SD; age:15.65 ± 0.61years) and combined feedback and verbal encouragement group (G3) (M±SD; age:15.55 ± 0.51 years). Muscle power (countermovement jump (CMJ); 5-Jump-Test (5JT)), agility (Illinois-test), sprint speed (10 and 30 m)]; technical skill and heart rate (HR) responses during 3 vs. 3 small sided basketball game (SSBG) were measured. Additionally, HR was continuously recorded and video analysis was used to quantify technical actions during SSBG. Results: The results showed greater improvements in muscle power of CMJ and 5JT for G3 compared to G2 (P&lt;0.001, ES=1.21, moderate, p&lt;0.001, ES= 4.74, large, respectively) and for G3 compared to G1 (P&lt;0.001, ES= 1.72 large; p=0.001, ES =6.86 large respectively). The time in the 10 m, 30 m sprints and agility decreased more profoundly for G3 compared to G2 (p&lt;0.001, ES=4.93, large; p&lt;0.001, ES=3.27, large, p&lt;0.001, ES=1.14, large, respectively).For technical skill, the ball contacts, successful balls, number of shots and successful shots were higher in G2compared with G1 (p&lt;0.001, ES=1.48 moderate; p&lt;0.001, ES=3.83, large; p&lt;0.001, ES=1.99, large; p=0.001, ES=2.41, large respectively), higher in G3 compared with G2 (p&lt;0.001,ES=-0.89, large, p=0.001, ES=-1.48 moderate; p=0.001, ES= 3.97, large; p&lt;0.001, ES=4.93, large, respectively). Furthermore, average heart rate was higher in G3 compared with G2 and G1 (p&lt;0.001, ES = 1.06, large; p&lt;0.001, ES=4.64, large, respectively). Conclusion: These findings indicate that the combination of feedback and verbal encouragement are more effective for achieving better results in physical fitness and technical skill than verbal encouragement group and control group.

Acute and Transient Match-Related Fatigue in University Female Footballers

This study aimed to examine the acute fatigue response experienced by female footballers during and after match-play. Twenty university footballers completed three trials of a countermovement jump on a force platform pre- and post-match-play (35 observations). External and internal loads were recorded during match-play via global positioning systems (GPS) and heart rate (HR), respectively. Match-play loads were split into thirds and analyzed via linear mixed model. Pre- and postjump metrics (n = 16) were analyzed using a paired samples t test. Significant decrements were observed between the first and final third for all external load metrics apart from sprint distance and accelerations (p &gt; .05). Relative concentric peak force (p = .035) was significantly increased postmatch, while a reduction was observed for relative concentric mean power (p = .034). The remaining 14 metrics did not display any significant changes (p &gt; .05). The stability of countermovement jump (CMJ) performance pre- to postmatch alongside the reductions within match support the notion of transient fatigue. Moreover, coaches can use this data (i.e., transient fatigue) to inform tactics in female football (i.e., substitutions) and conditioning regimes.

Acute effects of exercise-induced muscle damage on sprint and change of direction performance: A systematic review and meta-analysis.

The aim of this study is to determine the acute effects of resistance and plyometric training on sprint and change of direction (COD) performance in healthy adults and adolescents. A systematic literature search was conducted via Medline, Cinahl, Scopus and SportDiscus databases for studies that investigated: 1) healthy male, female adults, or adolescents; and 2) measured sprint or change of direction performance following resistance and plyometric exercises. Studies were excluded if: 1) resistance or plyometric exercises was not used to induce muscle damage; 2) conducted in animals, infants, elderly; 3) sprint performance and/or agility performance was not measured 24 h post muscle damaging protocol. Study appraisal was completed using the Kmet Quality Scoring for Quantitative Study tool. Forest plots were generated to quantitatively analyse data and report study statistics for statistical significance and heterogeneity. The included studies (n = 20) revealed sprint and COD performance was significantly impaired up to 72 hr following resistance and plyometric exercises; both protocols significantly increased creatine kinase (CK), delayed-onset muscle soreness (DOMS) and decreased countermovement jump (CMJ) up to 72 hr. The systematic review of 20 studies indicated that resistance and plyometric training significantly impaired sprint and COD performance up to 72 hours post-exercise. Both training protocols elevated exercise-induced muscle damage (EIMD) markers (CK, DOMS) and decreased CMJ performance within the same timeframe.

Comparison between Different Foot Types of Lower Limb Joint Kinematics and Kinetics during Counter Movement Jump Landing

Comparison between Different Foot Types of Lower Limb Joint Kinematics and Kinetics during Counter Movement Jump Landing

Changes in the force-time curve during a repeat power ability assessment using loaded countermovement jumps.

Repeat power ability (RPA) assessments traditionally use discrete variables, such as peak power output, to quantify the change in performance across a series of jumps. Rather than using a discrete variable, the analysis of the entire force-time curve may provide additional insight into RPA performance. The aims of this study were to (1) analyse changes in the force-time curve recorded during an RPA assessment using statistical parametric mapping (SPM) and (2) compare the differences in the force-time curve between participants with low and high RPA scores, as quantified by traditional analysis. Eleven well-trained field hockey players performed an RPA assessment consisting of 20 loaded countermovement jumps with a 30% one repetition maximum half squat load (LCMJ20). Mean force-time series data was normalized to 100% of the movement duration and analysed using SPM. Peak power output for each jump was also derived from the force-time data and a percent decrement score calculated for jumps 2 to 19 (RPA%dec). An SPM one-way ANOVA with significance accepted at α=0.05, was used to identify the change in the force-time curve over three distinct series of jumps across the LCMJ20 (series 1 = jumps 2-5, series 2 = jumps 9-12 and series 3 = jumps 16-19). A secondary analysis, using an independent T-test with significance accepted at p<0.001, was also used to identify differences in the force-time curve between participants with low and high RPA%dec. Propulsive forces were significantly lower (p<0.001) between 74-98% of the movement compared to 0-73% for changes recorded during the LCMJ20. Post hoc analysis identified the greatest differences to occur between jump series 1 and jump series 2 (p<0.001) at 70-98% of the movement and between jump series 1 and jump series 3 (p<0.001) at 86-99% of the movement. No significant differences were found between jump series 2 and jump series 3. Significant differences (p<0.001) in both the braking phase at 44-48% of the jump and the propulsive phase at 74-94% of the jump were identified when participants were classified based on low or high RPA%dec scores (with low scores representing an enhanced ability to maintain peak power output than high scores). A reduction in force during the late propulsive phase is evident as the LCMJ20 progresses. SPM analysis provides refined insight into where changes in the force-time curve occur during performance of the LCMJ20. Participants with the lower RPA%dec scores displayed both larger braking and propulsive forces across the LCMJ20 assessment.

Acute effects of repeated isoinertial lunges on jump and sprint parameters

Background and Study Aim. Understanding the relationship between repeated isoinertial lunges and jump and sprint parameters is an important factor in achieving success in sports requiring explosive strength and speed. The aim of this study was to examine the acute effects of repeated isoinertial lunges on jump and sprint parameters. Material and Methods. Volunteered 42 students from Sports Sciences Faculty were participated to the study. They were randomly divided into experimental group (EG) (n=22, age=22.8±1.1year, height=180.6±7.1cm, body weight=77.5±8.8kg) and control group (CG) (n=20, age=23.0±2.1year, height=173.1±5.6 cm, body weight=71.3±8.4 kg). As pre- and post-tests, each participant performed squat jump (SJ), countermovement jump (CMJ), and 30m sprint on a non-motorized treadmill. Isoinertial lunges were included in 8 reps with dominant leg (DL), 1 min rest, and 8 reps with non-dominant leg (NDL). As a statistical analysis, pre- and post-test differences were analyzed with independent t test between groups and paired t test within groups. The level of significance was taken as p≤0.05. Results. There were pre-test and also post-test differences between groups in SJ (p&lt;0.05) but there were no differences within groups. Both groups had significant pre- and post-test time, velocity, and power differences [for EG: p&lt;0.01, p&lt;0.001, p&lt;0.01; for CG: p&lt;0.001, p&lt;0.001, p&lt;0.01, respectively]. EG had significant pre- and post-test differences in stride frequency (SF) (p&lt;0.01). There was a post-test SF difference between two groups (p&lt;0.05). There were no statistically significant pre-test differences between the groups in 30m sprint parameters of NDL and DL. There were only significant post-test differences between the groups in SFDL (p&lt;0.005) and NDL horizontal force (HFNDL) (p&lt;0.01). EG had only significant pre- and post-test differences in SFDL and PNDL (p&lt;0.005 and p&lt;0.05). Conclusions. Detailed studies in SF and SFDL increases result by repeated isoinertial lunges should be beneficial focus on DL neuromuscular activation. Furthermore, incorporating repeated isoinertial lunges into training regimens could be a valuable strategy for enhancing specific aspects of athletic performance in sports that demand high levels of speed and explosive power.

Somatotype and Body Composition of Indian Male and Female Swimmers, and their Relationship to Countermovement Jump Performance

Introduction: The aim of this study was:1) to ascertain the anthropometric characteristics of Indian swimmers and 2) to investigate the potential association between these characteristics and countermovement jump metrics. Method: Forty-two national level Indian swimmers (18 females and 24 males) who regularly compete in national and/or international competitions, took part in the study. Anthropometric measurements were performed for body mass, stature, 8 skinfold sites, 3 girths, and 2 breadths. Somatotypes, body fat %, fat mass and lean body mass for all athletes were also calculated. A CMJ test was performed to measure vertical jump height, peak power output, and relative peak power output. Results: The Pearson correlation analysis of body composition variables and CMJ measures revealed a very large negative association between body fat percent and vertical jump height (R = - 0.726; p = 0.000) and between body fat percent and relative peak power (R = -0.757; p = 0.000); a large negative association between body fat percent and peak power (R = - 0.577; p = 0.000) and between fat mass and relative peak power (R = -0.560, p = 0.000); a moderately negative association between fat mass and vertical jump height (R = -0.490, p = 0.001); a very large positive association between lean body mass and peak power (R = 0.862, p = 0.000); and a large positive association between lean body mass and vertical jump height (R = 0.599, p = 0.000) and a large positive association between lean body mass and relative peak power (R = 0.530, p = 0.000); and a moderately positive association between BMI and peak power (R = 0.413, p = 0.007). Conclusion: There are significant differences in anthropometric characteristics when analyzing the anthropometric characteristics of Indian swimmers which could be attributed to the specific demands of each event. Anthropometric characteristics and body composition differences influence swim performance and vary according to gender, age and maturation status. A robust and significant positive correlation exists between lean body mass and vertical jump height suggesting that an enhancement of an individual's lean mass seems to have a positive impact on lower body power production in swimmers. Individualised training plans that focus on lower limb strength will have a potential positive effect on swim performance.

Comparison of Various Devices Used in the Evaluation of Vertical Jump Height

This study aimed to compare force plate, motion analysis, and mobile application methods for calculating vertical jump height. Twenty-nine male college students (age: 22.4 ± 1.0 years; height: 178.1 ± 6.2cm; body weight: 71.2 ± 8.0 kg) voluntarily participated in the study. Two countermovement jumps (CMJ) with 1-minute intervals on a force platform (BERTEC 4060-10) were performed. The countermovement jump performances were captured using an iPhone 11 (Apple Inc., USA). The experimental setup involved using three high-speed cameras, specifically the My Jump 2 and SIMI Motion 7.5. Obtained results from hip displacement (HD) data with motion analysis system showed that participants had significantly lower vertical jump height calculated from motion capture (p = 0.01; -8.3 ± 3.86, 95%CI; MyJump2-SIMI_HD = 1.24/3.30). It was also found that calculations from left and right foot displacement were higher than My Jump 2 results (95%CI; MyJump2-SIMI_RF = 0.66/2.93) and 95%CI (MyJump2-SIMI_LF) = (-0.63/2.65). In contrast, force plate calculations, known as the gold standard in the literature, were very similar to My Jump (95%CI; MyJumpII-FP) = (2.38/4.01). The findings indicate that the My Jump 2, used for assessing vertical jump height, may be a reliable alternative for determining vertical jump height instead of setting up gold standard methods. Individuals' athletic performance abilities and birth, gender, and sports preferences should be considered. Finally, when coaches or sports scientists intend to measure CMJ, My Jump 2 application can be recommended as a laboratory application as well as a practical and valid measurement method, especially for field applications.

Resistance Trainings for Enhancement in Jumping Performance: A Comparative Analysis

The primary purpose of programming is to organize training factor modifications that will provide the greatest possible improvement in performance. However, the best programming approach that results in enhanced neuromuscular adaptations is still unclear. This research set out to determine how three varying degrees of unpredictability within resistance training programs affected performance gains. Thirty-six people were split into three groups of twelve each: those who would receive training based on a weekly model (WM), those who would receive instruction based on a daily model (DM), and those who would receive training based on a session model (SM); Six weeks of back squat sessions comprised the training intervention. All participants received the same total training load during the course of six-week intervention. We tested the individual's maximum dynamic strength (1RM) in the back-squat, countermovement jump (CMJ), and squat jump (SJ) both before and after the training intervention. Significant gains were observed across the board (p&lt;0.05). The effect size (ES) of the session model in 1RM is just 0.29. Effect sizes for the daily model and session model in SJ are both moderate, at 0.61 and 0.41 respectively. The impact size in the CMJ daily model is quite moderate (0.51), while it is very large (0.99) in the session model. The results of this study show that changing the type of stimulus used in resistance training more often is a significant way to improve both strength and jumping ability at the same time.

The trend and evolution of training in volleyball: A bibliometric analysis of the last five years

Background Problems: The main focus on improving the performance of volleyball players and teams is through training that covers various aspects. Research Objectives: This study aims to analyse and explain trends and developments in the scientific literature regarding volleyball training over the past five years while identifying the most frequently featured training concepts, methods, and techniques in bibliometric studies in the field over the same period. Methods: Publication records between 2019 and 2023 were extracted from Scopus and the Web of Science, after which the bibliographic data set was administered using ScientoPy and VOSviewer. A term search was conducted with the keywords “training” OR “exercise” OR “practice” AND “volleyball”. Findings and Results: Results showed a total of 1.105 papers were published over the past five years, with 2022 recording the highest number of articles. The International Journal of Environmental Research and Public Health was the most prolific source, with 45 papers, and Clemente, F. M., was the most published author. The United States was the leading contributor in this research domain with 137 papers. The most frequently highlighted training concepts, methods, and techniques in this topic included vertical jumps, biomechanics, body composition, muscle strength, power, endurance training, injury prevention, agility, balance, and countermovement jumps. Conclusion: The results of this study emphasise the importance of developing training-related knowledge in volleyball. For future research contributions and recommendations, some things that can be taken into consideration are increased interdisciplinary studies, more applied research, use of technology in training, focus on health and injury prevention, comparative studies between countries, and research related to youth training in volleyball. This research provided a strong foundation for further development in understanding and optimising the training of volleyball players in the future.

Effects of Contrast Training with Two Sessions Weekly Frequency on Physical Fitness of University-Level Male Soccer Players

The purpose of this study was to compare the effects of a six-week contrast training intervention conducted twice per week during the preparatory period on the measures of physical fitness in university-level male soccer players. Materials and methods. Sixteen players were selected as participants and randomly assigned to an experimental group or an active control group. Data were collected at baseline and after a six-week training intervention period for 15 m and 30 m linear sprint, medicine ball throw (MBT), standing long jump (SLJ), countermovement jump (CMJ), change of direction speed (CODS), peak torque (both legs) during extension and flexion, and running-based anaerobic sprint test (RAST). Results. The analysis revealed reported significant small to very-large magnitude within-group improvement in all the dependent variables for the experimental group (p&lt;0.001–0.028) but not for the control group (p=0.066–1.000). Further, the analysis of covariance with the pre-test scores as covariates revealed significant differences at post-intervention assessments for all the dependent variables, favoring the contrast training group (p&lt;0.001–0.05). Conclusions. A six-week contrast training intervention with two weekly sessions during the preparatory period may be sufficient to induce small improvement in the 30 m linear sprint and isokinetic strength of both legs, moderate improvement in the 15 m linear sprint, and MBT, large improvements in SLJ, RAST, and a very large improvement in vertical jump (CMJ) and CODS.

Plyometric Training's Effects on Young Male Karatekas' Jump, Change of Direction, and Inter-Limb Asymmetry.

This study analysed the effects of performing a plyometric training programme on different types of jumping and specific changes of direction, and their respective asymmetries in karatekas. Twenty male karatekas (age 19 ± 4 years) were distributed in two groups, the control group (CG) and the experimental group (EG). The EG group (n = 10) performed a 6-week intervention of unilateral plyometric training, performing countermovement jumps (CMJ), drop jumps (DJ), and long jumps (SH). The tests performed at the beginning and at the end of the intervention were a unilateral and bilateral countermovement jump test (CMJ), single-leg hop test (SH), single-leg side-hop test (SSH), triple hop test (TH), and change of direction in a karate position test (MKUKS). The EG group obtained improvements in the CMJ with the stronger (p = 0.01; ES = 0.39) and weaker leg (p = 0.01; ES = 0.59), in the SH with the weaker leg (p = 0.01; ES = 0.45), in the SSH with the weaker leg (p = 0.03; ES = 0.33), in the MKUKS (p = 0.00; ES = 0.98), and improved the asymmetries obtained in the TH (p = 0.02; ES = -0.85). The GC group obtained significant differences in the CMJ with the stronger (p = 0.03; ES = 0.46) and weaker leg (p = 0.00; ES = 0.69), in the bilateral CMJ (p = 0.02; ES = 0.24), in the SH with the weaker leg (p = 0.00; ES = 0.34), in the TH with the stronger (p = 0.00; ES = -0.15) and weaker leg (p = 0.01; ES = 0.09), and in the MKUKS test (p = 0.04; ES = -0.94). A between-group analysis showed improvements of the EG over the GC in the TH with the stronger leg (p = 0.02; ES = 1.05). Performing plyometric training provides improvements in jumping, mainly in horizontal jumps, reducing inter-limb asymmetries in repetitive jumps.