Article

Reliability and Factorial Validity of Squat and Countermovement Jump Tests

August 2004
The Journal of Strength and Conditioning Research 18(3):551-555

DOI:10.1519/00124278-200408000-00028

Authors:

Goran Markovic

University of Zagreb

Igor Jukic

University of Zagreb

Marco Cardinale

Aspetar - Qatar Orthopaedic and Sports Medicine Hospital

The primary aim of this study was to determine reliability and factorial validity of squat (SJ) and countermovement jump (CMJ) tests. The secondary aim was to compare 3 popular methods for the estimation of vertical jumping height. Physical education students (n = 93) performed 7 explosive power tests: 5 different vertical jumps (Sargent jump, Abalakow's jump with arm swing and without arm swing, SJ, and CMJ) and 2 horizontal jumps (standing long jump and standing triple jump). The greatest reliability among all jumping tests (Cronbach's alpha = 0.97 and 0.98) had SJ and CMJ. The reliability alpha coefficients for other jumps were also high and varied between 0.93 and 0.96. Within-subject variation (CV) in jumping tests ranged between 2.4 and 4.6%, the values being lowest in both horizontal jumps and CMJ. Factor analysis resulted in the extraction of only 1 significant principal component, which explained 66.43% of the variance of all 7 jumping tests. Since all jumping tests had high correlation coefficients with the principal component (r = 0.76-0.87), it was interpreted as the explosive power factor. The CMJ test showed the highest relationship with the explosive power factor (r = 0.87), that is, the greatest factorial validity. Other jumping tests had lower but relatively homogeneous correlation with the explosive power factor extracted. Based on the results of this study, it can be concluded that CMJ and SJ, measured by means of contact mat and digital timer, are the most reliable and valid field tests for the estimation of explosive power of the lower limbs in physically active men.

Establishing the minimal important difference of the visual analog scale for assessing exercise-induced fatigue

Article

Full-text available

Apr 2025

Background Exercise-induced fatigue is a physiological state characterized by performance decline. The Visual Analog Scale (VAS) is one of the most commonly used subjective methods for evaluating exercise-induced fatigue. However, there is a limited interpretation of how much a change in this method indicates a fatigue status that matters to the exercise performance due to the lack of a well-established minimal important difference (MID). Methods This study is a secondary analysis of data from three trials. We analyzed individual participant data before and after exercise-induced fatigue. Anchor-based methods were used to determine the MID of the VAS for fatigue, using Countermovement Jump (CMJ) height as an anchor. Specifically, the MID was calculated using mean change, receiver operating characteristic (ROC) curve analysis, and linear regression methods. Results Data from 71 participants (80.28% male, 22.85 ± 2.51 years), corresponding to 230 person-time measurements, were included in this analysis. The CMJ height fulfilled the requirements to be used as an anchor. MIDs for mean change, ROC curve, and linear regression analysis were 48.51, 44.13, and 43.08, respectively. The Youden’s Index indicated that the MID calculated by the mean change method was the most relevant and reliable in distinguishing between fatigued and non-fatigued states. Conclusions This study establishes a MID (48.51) for interpreting changes in VAS scores. Future research utilizing VAS to assess exercise-induced fatigue should not only consider statistical differences but also examine whether the changes meet the MID threshold to interpret the actual impact of interventions. Trial registration Chinese Clinical Trial Registry (ChiCTR), Registration Number: ChiCTR2500095599 (Retrospectively registered; registration date: 09/01/2025).

Are the five consecutive vertical jumps a reliable evaluation tool in Olympic and Paralympic sprinters? A cross-sectional study

Article

Full-text available

Mar 2025

This study aimed to verify the validity and reproducibility of five vertical jump test (5VJT) as a more specific vertical jump height evaluation tool in elite Olympic and Paralympic sprinters. The present research was a cross-sectional study. For this, 49 sprinters participated, being eighteen with visual impairment, ten with cerebral palsy, seven leg amputees, six arm amputees, and eight non-disabled athletes. The athletes performed squat jump (SJ), countermovement jump (CMJ) and 5VJT. To compare jump height, analysis of variance (ANOVA) was used, intraclass correlation test (ICC) to evaluate the reliability, Bland and Altman to verify agreement of each pair of methods used (CMJ vs 5VJT, SJ vs 5VJT) and Pearson correlation to ascertain the level of association (CMJ vs 5VJT, SJ vs 5VJT) and between the subgroups. The level of significance set for the study was P<0.05. Excellent reliability for each method (CMJ-ICC=0.96, 95% confidence interval [CI]:0.96-0.97; SJ-ICC=0.89, 95%CI:0.87-0.90; and 5VJT=ICC=0.98, 95%CI:0.97-0.98) was found and strong to very strong association between them were found in visual impairment athletes-5VJT with CMJ (r=0.85), SJ (r=0.93), leg amputees-5VJT with CMJ (r=0.84), SJ (r=0.92), arm amputees-5VJT with CMJ (r=0.90), SJ (r=0.93), cerebral palsy-5VJT with CMJ (r=0.90), SJ (r=0.95) and AB-5VJT with CMJ (r=0.80), SJ (r =0.92). The reproducibility of ground contact time (GCT) showed good reliability for visual impairment (ICC=0.68, CV=9.5%), leg amputee (ICC=0.72; CV=13.8%) and cerebral palsy (CCI=0.77; CV=14.8%). These data suggest that 5VJT can be reliably applied to measure jump height and GCT, providing practical information about two important variables to monitor muscle fatigue (i.e., jump height and contact time).

Comparing-Speed-Agility-Quickness and Small-Sided-Games Training Effects on Speed and Power Performance in Young Soccer Players

Article

Full-text available

Nov 2024

Introduction. Soccer is a demanding sport that requires rapid and explosive movements. Enhancing speed and power is crucial for optimal performance in soccer players. Two training methods, Speed, Agility, and Quickness (SAQ) training and Small-Sided Games (SSG) training, are commonly used to improve these physical attributes. This study aimed to compare the effects of SAQ training versus SSG training on performance measures in young soccer players. Material and Methods. Twenty-four soccer players were randomly assigned to either an SAQ training group (n = 12) or an SSG training group (n = 12). An 8-week training program was implemented, and pre- and post-training assessments included 10-m and 20-m sprint tests, Zigzag Change of Direction Speed (CODS), Repeated Sprint Ability, Squat Jump (SJ), Counter-movement Jump tests. Statistical analysis involved paired t-tests to compare pre- and post-test results within groups and ANOVA to examine interactions between time and group effects. Results. SAQ and SSG training groups showed significant improvements across all measures (all p < 0.05). Time effects were significant (all p < 0.05), indicating overall effectiveness, with small time x group interactions (all p < 0.05; η2 ranging from 0.001 to 0.055). However, the percentages indicated a slight advantage for SAQ training in 10- and 20-meter speed and SJ, as well as for SSG training in RSAmean. Conclusions. Both SAQ and SSG training programs effectively enhance speed and power performance in young soccer players. Selection between programs can align with specific training goals, highlighting potential for further optimization in athletic development.

Relationship between the Reliability of Tennis-Specific Change of Direction (77COD) Test and Squat Jump–Countermovement Jump in Adolescent Tennis Players

Article

Full-text available

Oct 2024

The aim of this study was to investigate the reliability of the tennis-specific change of direction (77COD) test with vertical jump tests (Squat Jump and Countermovement Jump) in adolescent tennis players. A total of 58 athletes (31 girls, 27 boys) actively playing tennis, with an average age of 10.57 ± 2.54 years, participated in the study. Tests and retests were completed within 2 weeks. Bland–Altman (B&A) plots were established and Pearson’s correlation analysis was conducted on the 77COD, CMJ, and SJ tests. Simple linear regression analysis (enter method) was used to determine the significant predictors of the 77COD variable from the SJ-CMJ variables. The SJ and CMJ were found to be highly negatively correlated with the 77COD test (−0.72 ≤ r ≤ −0.74). The test–retest reliability of the 77COD test was found to be very high, with an intraclass correlation coefficient (ICC) of 0.95. Our findings showed that the 77COD test is suitable for determining COD ability in adolescent tennis players. In addition, vertical jump heights are an informative and practical performance indicator for 77COD. In conclusion, the 77COD test is a COD test that can be used in coaching practices without the need for complex testing materials.

Individual responses to encapsulated caffeine and caffeine chewing gum on strength and power in strength-trained males

Article

Full-text available

Apr 2025
Sports Nutr Rev J

Background: Liquid-dissolved and encapsulated powder are two popular ways to consume caffeine for performance-enhancing effects. Caffeine in other delivery methods, such as chewing gums, orally dissolvable strips, gels, mouthwashes, energy drinks, and nasal sprays, is believed to be absorbed more quickly into the bloodstream. Inter-individual responses to caffeine's enhancing effects are recognized. The present study examined the inter-individual responses to the acute effects of encapsulated caffeine and caffeinated chewing gum on the lower-body isokinetic and iso-metric strength and power in strength-trained males. Method: A randomized, cross-over, placebo-controlled study was conducted with 15 strength-trained males (age: 25 ± 4 years, height: 176 ± 7 cm, weight: 75 ± 11 kg, habitual caffeine intake: 66 ± 15 mg·day −1). Participants were randomly assigned to three conditions: i) caffeinated chewing gum (CG), ii) caffeine capsule (CC), and iii) starch capsule as a placebo (PLA). Participants consumed approximately 3 to 4.5 mg·kg −1 of caffeine 60 minutes before testing. The washout period between conditions was one week. Participants performed the Sargent jump test, followed by a 5-minute active recovery (walking). Subsequently, isokinetic strength and power (60°/s and 180°/s) and isometric strength (45° and 60°) parameters were measured for knee extensor and flexor muscles. Data were analyzed using one-way repeated measures ANOVA and Bonferroni post hoc tests, with significance set at p ≤ 0.05. Responders to the caffeine conditions were identified using the smallest worthwhile change (SWC) analysis. Results: In knee extensors, 1) average peak torque and power at 60°/s were higher in CC (p = 0.045; + 11.2% and p = 0.038; + 14.1%) and CG (p = 0.044; + 7.3% and p = 0.015; + 11.4%) compared to PLA with a co-response rate of 60% and 66%, 2) maximum voluntary isometric contraction at 45° (MVIC-45°) was higher in CC compared to PLA (p = 0.031; + 10.1%), and 3) MVIC-60° was higher in CG ARTICLE HISTORY (http:// creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. The terms on which this article has been published allow the posting of the Accepted Manuscript in a repository by the author(s) or with their consent. compared to PLA (p = 0.037; + 10.1%) with a co-response rate of 60%. In knee flexors, 1) time to peak torque at 60°/s was higher in CG compared to PLA (p = 0.011; + 18.2%) with a co-response rate of 46%, 2) average rate of force development at 60°/s was higher in CC (p = 0.007; + 24.1%) and CG (p = 0.050; + 20.6%) compared to PLA with a co-response rate of 53%, and 3) average power at 180°/s was higher in CC compared to PLA (p = 0.033; + 18%) with a co-response rate of 46%. However, there were no differences between other strength indicators in the knee extensors and flexors between the different conditions. Vertical jump height (VJH) was higher in CC (p = 0.001; + 5.5%) and CG (p = 0.001; + 6.) compared to PLA, with a co-response rate of 53%. Conclusion: Caffeine supplementation in CC and CG forms significantly enhanced lower-body strength, power, and vertical jump height in strength-trained males, with over ~50% of participants exceeding the SWC thresholds across key performance metrics. CC showed slightly higher responder rates for strength parameters, while CG excelled in time-dependent measures, supporting their use as effective and flexible ergogenic aids.

Relationships Between Sport-Specific Anaerobic Tests, Interlimb Asymmetry, and Bilateral Deficit as Measured from Vertical Jump Performances in Highly Trained Taekwondo Athletes

Article

Full-text available

Mar 2025

The present study investigated the effect of inter-limb asymmetry and bilateral indexes (BLIs) in power performance, assessed by squat jump (SJ) and countermovement jump (CMJ), on sport-specific anaerobic performance. Forty-eight taekwondo athletes (24 males and 24 females; mean ± SD, age: 19.8 ± 2.1 years) performed randomly, in separate sessions, SJ and CMJ tests using the right, left, and both legs to determine the asymmetry and BLI, the 10 s Frequency Speed of Kick Test (FSKT 10s), and its multiple version (FSKT mult). FSKT 10s was positively correlated with CMJ asymmetry (ρ = 0.299, p = 0.039, low) and SJ BLI (r = 0.596, p < 0.001, large), and negatively correlated with CMJ BLI (r = −0.472, p = 0.001, moderate). Similarly, FSKT mult was positively correlated with SJ BLI (ρ = 0.632, p < 0.001, large), and negatively correlated with CMJ BLI (ρ = −0.532, p < 0.001, large). CMJ and SJ BLI explained 45.9% of the variance of the FSKT 10s performance, whilst they explained 55.7% of the variance of FSKT mult performance. These results highlight the importance of managing both interlimb asymmetry and bilateral deficit indexes to achieve better performance by improving the strength of the non-dominant leg and using exercises that are performed bilaterally despite unilateral movements being predominant in taekwondo, which can potentially enhance the effectiveness in sport-specific actions

Novel Use of Generalizability Theory to Optimize Countermovement Jump Data Collection

Article

Full-text available

Mar 2025

This study aimed to evaluate the reliability of countermovement jump (CMJ) performance metrics across five NCAA Division I varsity sports using Generalizability Theory (G-Theory). Three hundred male athletes from football, hockey, baseball, soccer, and lacrosse performed three or more CMJs on dual-force platforms. G-Theory was applied to identify variance components and determine reliability coefficients (Φ) for 14 key metrics. Metrics requiring more than three jumps to achieve Φ 0.80 were deemed unreliable. Metric reliability varied by sport and phase of movement. Metrics associated with the eccentric phase (e.g., Eccentric Duration, Deceleration Rate of Force Development Asymmetry) demonstrated lower reliability, often requiring >3 jumps. Reliable metrics across sports included Phase 1 Concentric Impulse and Scaled Power, requiring three trials or fewer. CMJ reliability is sport- and metric-specific. Practitioners should prioritize reliable metrics and adjust protocols to balance data quality and practicality, particularly when monitoring eccentric characteristics.

Inter and intra-session reliability and validity of the Performanz JumpR device for measuring different jump performances in young male soccer players

Article

Full-text available

Feb 2025

This study aimed to determine the inter- and intra-session reliability and validity of the Performanz JumpR device for measuring different jump performances in young male soccer players. Fifty-four young male soccer players (mean age: 15.90 ± 0.70) completed three maximal squat jumps (SJ), countermovement jumps (CJ), and 40 cm drop jumps (DJ) over two separate days. These jumps were assessed using both a contact mat and the Performanz JumpR device. The different jump performances were compared using several statistical methods, including the intraclass correlation coefficient (ICC = 2.1), Bland-Altman plots, Pearson product-moment correlation coefficient ( r), Cronbach’s alpha (α), and the coefficient of variation (CV). Results showed almost perfect agreement between the Performanz JumpR device and the contact mat for SJ, CJ, and 40 cm DJ values, with jump heights and peak powers yielding ICC values between 0.98 and 0.99 during both assessment sessions. Additionally, the Pearson product-moment correlation coefficient showed an almost perfect correlation between the measurements from the Performanz JumpR device and the contact mat for SJ, CJ, and 40 cm DJ values, with r values ranging from 0.96 to 0.99 during the first and second assessment sessions. The Performanz JumpR device demonstrated very good intra-session reliability for the three jumps in each set, with the following results: SJ (jump height, α = 0.98, CV = 2.02; peak power, α = 0.99, CV = 1.35), CJ (jump height, α = 0.98, CV = 2.20; peak power, α = 0.99, CV = 1.46), and 40 cm DJ (jump height, α = 0.97, CV = 2.61; peak power, α = 0.99, CV = 1.79). When analyzing the inter-session reliability of the Performanz JumpR device and contact mat across all players, almost identical correlations were observed between the two instruments for SJ, CJ, and 40 cm DJ regarding jump heights and peak powers ( r = 0.96–0.99) between the first and second assessment sessions. Additionally, the Bland-Altman plots demonstrated an almost agreement, with a systematic bias identified between the Performanz JumpR device and the contact mat for SJ, DJ, and 40 cm DJ values ( p < 0.01). Overall, the Performanz JumpR device provided reliable inter-session and intra-session data, as well as valid measurements for maximal jump height and peak power during SJ, CJ, and 40 cm DJ in young male soccer players.

Sex differences in upper and lower strength and their association with body composition among university students

Article

Full-text available

Sep 2024

[Purpose] Sex strongly influences physical performance throughout adolescence, and excess fat mass is associated with several health and performance impairments. This study aimed to evaluate whether variations in strength between men and women dependent on lean mass and body fat content.[Methods] This cross-sectional, quasi-experimental, non-probabilistic study involved 44 university students (22 men and 22 women, aged 19–29). Handgrip strength (HGS) was measured using an adjustable handgrip dynamometer, body composition was assessed using bioimpedance, and countermovement jumps (CMJ) were measured using a force platform. Data were analyzed using ANOVA to compare HGS and CMJ based on body mass, and the Pearson correlation coefficient was applied to examine the relationships between grip strength, body composition, and jump test performance.[Results] Strength is significantly higher in men compared to women, as is countermovement jump. The strength of women corresponded to over 50% of that of men, whereas the quantity of lean mass in women corresponded to 55% of that of men. We found a significant relationship between strength and lean mass.[Conclusion] This study supports the idea that both upper- and lower-body strengths are strongly influenced by lean mass, thereby contributing to sex differences. The primary factor in body composition that explains the disparities in HGS and CMJ between sexes is the proportion of fat mass to lean mass. Finally, the sex disparities observed between body composition and strength depend on lean mass content.

Age and Sex Differences in Physical Performance Among Adolescent Team Sport Athletes

Article

Full-text available

Apr 2025
EUR J SPORT SCI

The study aimed to explore the differences in physical performance characteristics across various age groups (U14, U16, and U18) and sexes in adolescent team sport athletes. 473 adolescent Norwegian football and handball players were recruited for anthropometrical and physical performance testing. Performance improved with age in both boys and girls, showing significant differences between age categories. Across all tests, boys outperformed girls, and the sex difference doubled from U14 to U16, such as −5.1% to −10.3% for 30 m sprint, −5.6% to −9.8% for change of direction (CoD), 11% to 21% for countermovement jump (CMJ), and from 5% to 16% for relative strength. No further increase in differences between sexes was observed in the U18 age group. All age groups showed substantial intragroup variability in physical performance tests and anthropometric measures. The main findings from the study were increased sex differences from U14 to U16, but no further increase in sex difference from U16 to U18s as well as considerable individual variation in performance. Girls, maturing earlier than boys and showing less physical performance development, may benefit from earlier introduction to strength training to boost their physical development. Moreover, the considerable individual variation underscores the need for tailored individualized programs.

The effect of time of day and menstrual cycle on physical performance and psychological responses in elite female Tunisian volleyball players

Article

Full-text available

Apr 2025

Background The influence of circadian rhythms and menstrual cycle phases on athletic performance and psychological responses is critical for optimizing training and competition strategies for female athletes. This study aimed to investigate the effects of time of day and menstrual cycle phases on the physical performance and psychological responses of elite female Tunisian volleyball players. Methods Thirteen elite female volleyball players were assessed during three different phases of their menstrual cycle (menstrual, follicular, and luteal) and at two different times of day (morning and evening). Physical performance was evaluated using the Modified Agility Test (MAT), Reactive Agility Test (RAT), and Repeated Sprint Ability (RSA) Test. Psychological responses were measured using the Profile of Mood States (POMS), Hooper’s Questionnaire, Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, Vis-Morgen Questionnaire, and Spiegel Questionnaire. Results Significant effects of menstrual cycle, time of day, and competition on physical performance, cognitive function, mood, and sleep parameters were found. Physical performance, including the Countermovement Jump (CMJ), the Modified Agility T-test (MAT) and the Reactive Agility test (RAT), was higher in the afternoon than in the morning across all menstrual phases (CMJ: p < 0.001, η² = 0.836; MAT: p < 0.001, η² = 0.777; RAT: p < 0.001, η² = 0.859). After the competition, performance decreased significantly, especially in the follicular and luteal phases. As measured by the Stroop test, cognitive function showed significant diurnal effects (p < 0.001, η² = 0.910), with pre-competition performance being better in the afternoon. Mood disturbances (POMS) increased after the competition, especially in the morning and during the luteal phase (p < 0.001, η² = 0.961). Sleep parameters were significantly influenced by time and menstrual cycle, with higher fatigue (Hooper score: p < 0.001, η² = 0.754) and poorer sleep quality (PSQI: p < 0.001, η² = 0.627) in the morning, especially after the competition. Conclusion Our results suggest that aligning high-intensity training and competitions with afternoon circadian peaks may enhance physical and cognitive performance in elite female athletes. Recovery strategies and workload adjustments should account for menstrual phases, particularly reducing morning demands during the luteal phase to mitigate fatigue and mood disruptions. Integrating circadian timing with menstrual cycle monitoring offers a practical, evidence-based approach to optimize athlete readiness and resilience.

Characterization and Comparison of Athletic Performance and Change of Direction Deficit Across Youth Futsal Age Groups

Article

Full-text available

Mar 2025

Background/Objectives: Futsal players need peak strength, functional capacity, speed, and explosive lower-limb power for optimal performance. The aim of this study was to (i) characterize and compare anthropometric characteristics, lower limb strength/power, dynamic balance, linear sprint speed, COD performance, and COD deficit across young futsal age groups and (ii) identify key predictors of COD deficit. Methods: Thirty-three male futsal players from three age groups (U13, U15, and U17) were tested. Results: All anthropometric variables showed significant group effects with moderate to strong effect sizes, where U17 presented the largest values, followed by U15 and U13. Strength and power variables presented the same trend. The dynamic balance differed significantly across groups. Significant differences between groups with moderate effect sizes were noted in linear sprints (F = 19.54, p < 0.001, η2 = 0.57), zigzag (F = 19.54, p = 0.002, η2 = 0.35), and COD deficit (F = 19.54, p < 0.001, η2 = 0.46). Post hoc tests revealed that U13 and U15 outperformed U17 in the COD deficit (p < 0.002). The COD deficit showed a quadratic relationship with age, initially improving but later declining in older players (p < 0.001). The body mass and the posteromedial relative difference predicted the COD deficit, with the coefficient of determination (R2) explaining 39% of the COD variance. Conclusions: Coaches and practitioners should utilize COD drills to target various movement patterns and account for pubertal timing, as growth can impact performance.

Comparison of Physical Characteristics, Strength and Power Performance Between Elite 3 × 3 and 5 × 5 Male Basketball Players

Article

Full-text available

Mar 2025

Background/Objectives: The aim of this study was to explore the differences in physical characteristics, leg strength, and jumping performance between 3 × 3 and 5 × 5 male basketball players. Methods: Twelve elite-level 5 × 5 basketball players (26.0 ± 13.0 years; 201.4 ± 6.6 cm; 95.50 ± 11.50 kg) and twelve elite-level 3 × 3 basketball players (26.7 ± 7.3 years; 193.0 ± 5.1 cm; 98.03 ± 9.77 kg), all male, were enrolled in the study. After anthropometric measurements and standardized warm ups, countermovement jump (CMJ), drop jump (DJ) and isokinetic strength testing were conducted, respectively. Results: An independent two-sample t-test revealed that 5 × 5 athletes were notably (p < 0.005) taller, with a lower body fat percentage (11.9 ± 3.6% vs. 18.6 ± 10.9%) and higher quadricep strength (317.21 ± 36.54 N·m vs. 284.76 ± 29.77 N·m and 313.32 ± 24.08 N·m vs. 285.87 ± 31.2 N·m for left and right leg, respectively). Conversely, 3 × 3 players displayed superior CMJ performance in concentric and eccentric peak forces, peak power, and reactive strength index. In the DJ, 3 × 3 players also excelled in eccentric peak force, reactive strength index, and jump height. Conclusions: The findings indicate that while 5 × 5 basketball players excel in body physique and in the strength of their lower body, 3 × 3 basketball players outperform them in power-related metrics.

Does Olympic Weightlifting Enhance Strength, Power, and Speed in Adolescent Rugby Union Players?

Article

Full-text available

Mar 2025

This interventional controlled study investigated the effects of Olympic weightlifting (OWL) on strength, power, and speed in adolescent rugby union players. Under-17 rugby union players were divided into two groups (WLG and CON) [n: 46, age: 15.4 (0.5) years, stature: 175 (6.1) cm, body mass: 73.7 (15.6) kg]. The WLG participated in an 8-week OWL program. Pre- and post-intervention assessments measured countermovement jump height, 10m and 30m sprint times, and a 5RM back squat. Results showed no substantial differences between groups at pre- and post-intervention for strength, power, and speed. Strength significantly improved for both groups from pre-to-post. In addition, the WLG demonstrated a greater rate of strength development in comparison to the CON group (MLE = 7.30, SE = 1.83, 95%CI = [3.65, 10.94], t = 3.99, p < 0.001). Power did not present substantial changes between pre and post for both groups. Speed performance decreased from pre to post for both WLG and CON (p < 0.001). Nonetheless, smaller decreases were observed in the WLG for 10m (+0.05 vs +0.09 sec) and 30m (+0.12 vs +0.20 sec) sprints. Furthermore, anthropometrics (i.e., stature and body mass) proved to be important factors contributing to strength, power, and speed development. The study found no clear evidence to support the benefit of OWL in developing strength, power, and speed in adolescent athletes without prior experience with these exercises. However, OWL may enhance absolute strength gains and mitigate speed performance declines in youth rugby players. Stature and body mass significantly affected these performance metrics, highlighting the need to consider individual differences and developmental changes. Continuous assessment and careful adjustment of training programs are crucial during adolescence to account for variations in stature and body mass.

Monitoring fitness and fatigue for coaches

Conference Paper

Mar 2024

Effects of repeated use of post-exercise infrared sauna on neuromuscular performance and muscle hypertrophy

Article

Full-text available

Mar 2025

Purpose The aim of this study was to investigate whether regular use of infrared sauna (IRS) after training can promote neuromuscular performance and positive changes in body composition during a 6-week training period. Methods Forty female team sport athletes were pair-matched into two groups: IRS ( n = 20) and control (CON; n = 20). Physical performance tests, body composition and hypertrophy measurements (dual-energy x-ray absorptiometry and ultrasound of m. vastus lateralis) were performed PRE and POST a 6-week strength and power training period, involving 2–3 sessions per week. Performance tests included a 20 m sprint, squat jump (SJ), countermovement jumps with body weight (CMJ) as well as with 15, 25, and 50% additional load (CMJ15%, CMJ25%, and CMJ50%), and a maximal isometric leg press (MVC). Participants in the IRS-group used IRS (10 min, 50℃) after training three times per week. Results Training improved neuromuscular performance and muscle hypertrophy in both groups ( p < 0.05). Following the discovery of an interaction effect for CMJ15% height ( p = 0.002) and peak power ( p = 0.010), post hoc tests revealed higher jump height POST-IRS ( p = 0.006) and PRE-CON ( p = 0.023) compared to PRE-IRS, and higher peak power POST-IRS ( p = 0.002) compared to PRE-IRS. Furthermore, an interaction effect was observed for 5 m split time of the 20 m sprint ( p = 0.020), but no differences were found between groups and timepoints. There were no interactions for the hypertrophy measures. Conclusion Incorporating post-exercise IRS bathing does not significantly impact hypertrophy gains, but might boost long-term power production capabilities.

Dynamic Assessment Methods for ACL Injury Risk: A Narrative Review With Implications for Prevention and Rehabilitation

Article

Mar 2025
Strength Condit

Anterior cruciate ligament (ACL) injuries present significant challenges in athletic populations, particularly among young female athletes who experience elevated risks during critical developmental stages. Effective prevention and rehabilitation require accurate assessment of neuromuscular function. This review explores dynamic jumping assessments across the stretch-shortening cycle (SSC) continuum to assess ACL injury risk factors and guide rehabilitation. Specifically, the tuck jump assessment (TJA) is highlighted for its utility to reveal neuromuscular control deficits across repetitive jumping cycles, which are often missed in single-repetition tests. Recent advancements in kinetic analyses of the TJA offer valuable insights into ground reaction forces, interlimb asymmetries, and SSC function, enhancing clinicians' ability to detect potential injury risks and monitor recovery in athletes with ACL reconstruction. Practical applications for incorporating the TJA into ACL injury screening and rehabilitation are discussed, emphasizing its role in progressive return-to-sport protocols. By integrating dynamic assessments like the TJA, clinicians can better identify at-risk athletes and tailor interventions to reduce reinjury rates and improve long-term athletic development outcomes.

Reactive Strength Index Modified Differentiates Starters and Non-Starters in Female Volleyball National Team Players

Article

Full-text available

Mar 2025

Jumping ability is crucial in volleyball, where both jump height and execution speed significantly influence performance. Previous research has yielded mixed findings on the role of jump force-time characteristics in determining starting status among female volleyball players. This study examined the relationship between countermovement jump (CMJ) force-time metrics and starting status in elite female volleyball players to identify key performance indicators. Nine national team athletes (five starters, four non-starters) performed CMJs on a force platform. Force-time variables from distinct jump phases were analyzed. Reactive strength index modified (RSImod)-the ratio of jump height to time to takeoff was used to assess lower-body explosiveness and reactive strength. Starters demonstrated significantly higher RSImod scores and relative propulsive mean force, indicating superior ability to generate force rapidly. Moderate-to-large effect sizes favoring greater relative strength (force and power normalized to body mass) were observed but were not statistically significant. Reactive strength, as reflected by RSImod, is a key differentiator of starting status in elite female volleyball players. Relative strength also appears to contribute to performance but requires further exploration. Training programs should prioritize lower-body power and reactive strength through targeted plyometric and resistance exercises to enhance volleyball performance.

Effects of a 30 K Military Loaded Carriage on the Neuromuscular System in Spanish Army Marines

Article

Full-text available

Mar 2025

Infantry soldiers must cover long distances carrying heavy and bulky combat equipment. Since the beginning of their training, Spanish Marines have undergone this characteristic and demanding test. However, little is known about its effects on neuromuscular function and recovery in the days following the test. Twenty-six Spanish Marines completed the test, three of whom suffered injuries and had to withdraw from the study, resulting in a final sample of twenty-three Marines. These participants underwent evaluations before (pre), immediately after (post), and 24 and 48 h post-exercise, following a 30 km endurance march carrying their 34 kg combat equipment. A repeated-measures ANOVA, paired-samples t-test, and effect size (ES) analysis were conducted; the results are presented as mean ± SD. The significance level was set at p ≤ 0.05. The variables and p-values of changes over time are presented. Isometric mid-thigh pull (IMTP) (p = 0.004), countermovement jump (CMJ) (p ≤ 0.001), rating of fatigue scale (ROF) (p ≤ 0.001), maximum pull-ups in two minutes (PUmax) (p ≤ 0.001), body mass (BM) (p ≤ 0.001), hand grip strength (HGS): dominant (p = 0.180) and non-dominant (p = 0.616), and incident reports (IRPE) showed a significant increase over time and between the first 10 km and last 5 km in fatigue, muscle pain, joint pain, shortness of breath, excessive sweating (p ≤ 0.001), and muscle tremors (p = 0.028), except for palpitations (p = 0.189). In conclusion, the results indicate that the test had a significant impact on neuromuscular function, with no recovery observed in overall strength and lower limb power after 48 h, even though their perceived fatigue decreased substantially. The resilient spirit of operational military units and their philosophy of always being ready for combat could increase the injury rate.

Effects of Inertial Measurement Unit Location on the Validity of Vertical Acceleration Time-Series Data and Jump Height in Countermovement Jumping

Article

Full-text available

Mar 2025

Inertial measurement units (IMUs) are an example of practical technology for measuring countermovement jump (CMJ) performance, but there is a need to enhance their validity. One potential strategy to achieve this is advancing the literature on IMU placement. Many studies opt to position a single IMU on anatomical landmarks rather than determining placement based on anthropometric principles, despite the knowledge that linear mechanics act through the segmental centers of mass of the human body. The purpose of this study was to evaluate the impact of positioning IMU sensors to approximate the trunk and lower-extremity segmental centers of mass on the validity of vertical acceleration measurements and jump height (JH) estimation during CMJs. Thirty young adults (female n = 10, 21.3 (3.8) years, 166.1 (4.1) cm, 67.6 (11.3) kg; male n = 20, 22.0 (2.6) years, 179.2 (6.4) cm, 83.5 (17.1) kg) from a university setting participated in the study. Seven IMUs were positioned at the approximate centers of mass of the trunk, thighs, shanks, and feet. Using data from these sensors, 15 whole-body center of mass models were developed, including 1-, 2-, 3-, and 4-segment configurations derived from the trunk and three lower-body segments. The root mean square error (RMSE) of vertical acceleration was calculated for each IMU model by comparing its data against vertical acceleration measurements obtained from a force platform. JH estimates were calculated using the take-off velocity method and compared across IMU models and the force platform to evaluate for systematic bias. RMSE and JH values from the best-performing 1-, 2-, 3-, and 4-segment IMU models were analyzed for main effects using one-way analyses of variance. The best performing 2-segment (trunk and shanks; RMSE = 2.1 ± 1.3 m × s−2) and 3-segment (trunk, thighs, and feet; RMSE = 2.0 ± 1.2 m × s−2) IMU models returned significantly lower RMSE values compared to the 1- segment (trunk; RMSE = 3.0 ± 1.4 m × s−2) model (p = 0.021–0.041). No systematic bias was detected between the JH estimates derived from the best-performing IMU models and those obtained from the force platform (p = 0.91–0.99). Positioning multiple IMU sensors to approximate segmental centers of mass significantly improved the validity of vertical acceleration time-series data from CMJs. The findings highlight the importance of anthropometric-based IMU placement for enhancing measurement accuracy without introducing systematic bias.

A Comparison of Bilateral vs. Unilateral Flywheel Strength Training on Physical Performance in Youth Male Basketball Players

Article

Full-text available

Feb 2025

Background/objectives: This study aimed to compare the effects of bilateral and unilateral flywheel training programs on leg strength, sprint performance, jumping, and change of direction ability in young basketball players. Methods: Twenty-two youth male basketball players were randomly assigned to two groups: the unilateral group (UG; n = 11; age = 15.5 ± 0.5 years) and the bilateral group (BG; n = 11; age = 15.2 ± 0.4 years). Both groups participated in a six-week flywheel training intervention (UG: split squat; BG: half squat) alongside their regular basketball activities. Performance measures included change of direction ability (5-0-5 test), knee extension 60 degrees/s leg strength (EX60), bilateral and unilateral countermovement jump heights (CMJ, CMJL, and CMJD), reactive strength index (RSI), and 5 m and 20 m sprint times (SPR5m and SPR20m). A 2 × 2 ANOVA was used to evaluate pre- to post-intervention changes. Results: Significant interaction effects were observed for the 5-0-5 test (F = 13.27; p = 0.02), with pre–post improvements of 8.4% and 13.3% for the BG and UG, respectively. Both groups showed significant CMJ improvements (11.4%, ES = 0.69 for the BG; 14.6%, ES = 1.4 for the UG). The UG demonstrated greater unilateral jump improvements compared to the BG. Significant RSI improvements were found for both groups (BG: 19.6%, ES = 0.95; UG: 19.6%, ES = 0.77). Both groups improved on sprint performance, with the UG showing slightly larger effect sizes. Conclusions: Unilateral flywheel strength training appeared to be a more effective strategy than bilateral training for enhancing strength, sprinting, jumping, and change of direction ability in youth basketball players.

Unveiling the predictive role of motor competence and physical fitness on inhibitory control in preschool children: a cross-sectional study

Article

Full-text available

Feb 2025
BMC Pediatr

Background During the preschool years, children experience rapid development of inhibitory control (IC). This period is also crucial to foster the establishment of the foundations of physical fitness (PF) and motor competence (MC), which are essential for long-term health outcomes. This study aimed to investigate the predictive roles of PF and MC in IC in preschool children. Method A total of 139 children (78 boys and 61 girls) participated in the study, with a mean age of 5.76 ± 0.30 years and a body mass index (BMI) of 16.15 ± 1.94 kg/m². Children performed the Go/No-Go test, Körperkoordinationstest für Kinder (KTK3+) test, static and dynamic balance tests, a pro-agility and countermovement jumping (CMJ) test. Results The findings showed that there was a positive association between MCT and accuracy number (AC) (go) (β = 0.079, 95%CI: 0.051–0.107), AC (no go) (β = 0.022, 95%CI: 0.003–0.041). However, between MCT and reaction time (RT), there was a negative relationship (β =

\:-

0.497, 95%CI:

\:-

0.988 -

\:-

0.006). MCT scores showed a significant positive relationship with AC (go), with a beta coefficient of 0.309 (95% CI: 0.181, 0.436). This finding further underscores the robustness of this relationship. The PF indicator agility showed a negative relationship with AC (go) (β = -3.638 [-5.590, -1.687]) and static balance was negatively related to RT (β = -34.767, 95% CI [0.018, 0.165]). Conclusions Overall, this study indicates that MC, rather than general PF, is strongly associated with the concurrent level of IC during the preschool period. These findings highlight the potential importance of promoting MC through targeted interventions that may support cognitive function in young children. Further longitudinal research is recommended to explore the causal relationships and long-term effects of these interventions. Study registration Research protocol number: 2022.214.11.15.

Effects of Root Extract of Ashwagandha (Withania somnifera) on Perception of Recovery and Muscle Strength in Female Athletes

Article

Full-text available

Feb 2025
EUR J SPORT SCI

Ashwagandha is a supplement with the potential to improve exercise performance. However, research on its impact on female athletes remains limited. This study investigates the effects of ashwagandha on exercise recovery and muscle strength in professional female athletes, addressing a gap in understanding its role in this underrepresented population. Female footballers were randomly assigned to a 600 mg/day ashwagandha root extract group (ASH, n = 15; age: 26.0 ± 4.9 years, height: 1.66 ± 0.1 m, body mass: 61.5 ± 7.5 kg, and career: 15.2 ± 7.4 years) or a placebo group (PLA, n = 15; age: 23.5 ± 5.5 years, height: 1.66 ± 0.1 m, body mass: 61.5 ± 6.0 kg, and career: 13.1 ± 4.9 years). Recovery was assessed with total quality recovery (TQR), Hooper Index (HI) and rate of perceived exertion (RPE). Strength was assessed by hand grip, medicine ball throw (MBT), countermovement jump (CMJ) and peak power. Dietary intake was recorded prior to baseline measurements. Repeated measures ANOVA, Bonferroni test, independent t‐tests and ANCOVA were used in the analysis. A significant group × time interaction effect was found for TQR (p = 0.026), with the post‐hoc analysis revealing a significant difference between ASH and PLA at 28 days (p = 0.039). Perceived sleep quality from HI improved significantly in ASH compared to PLA (p = 0.038), with a significant change at 14 days. The ANCOVA analysis highlighted the significant influence of carbohydrate intake on hand grip strength (p = 0.005), MBT (p < 0.001) and body mass (p < 0.001). A dosage of 600 mg of ashwagandha root extract for 28 days may improve TQR and enhance perceived sleep quality in female footballers. Future research should investigate the optimal dosage and test across a broader range of athletic populations. Trials Registration: The trial is registered on ClinicalTrials.gov with the ID NCT06264986

Vitamin D and its relationship to performance and health during a competitive period in elite women's basketball and volleyball players

Article

Full-text available

Feb 2025

Vitamin D [25(OH)D] is a key nutrient, although its level is often low in the general population. To investigate the relationship between vitamin D levels and muscle performance, and to analyze how vitamin D changes during a 16‐week competitive season and its relationship to the performance tests performed. Participant characteristics: age 25.1 ± 4.7 years; height 1.8 ± 0.1 m, and body mass 73.9 ± 15.4 kg. Vitamin D levels (ng/mL) were at T1 (September): 33.7 ± 14.7 (n = 23), and at T2 (January): 26.1 ± 7.3 (n = 23). Over 16 weeks of competition, participants' blood was analyzed to determine their vitamin D levels. Their athletic abilities were evaluated through various tests: vertical jumps (standing jump and countermovement jump); 20‐m sprint without direction changes; and intermittent endurance test; the vitamin D level decreased from T1 to T2 by −22. 40% [p < 0.05] but performance improved in all tests performed (SJ: 4.57%; CMJ: 6.94%; VO2max: 4.99% [p < 0.05]; 20 m: −1.83%). There is a relationship between vitamin D levels and physical performance in female indoor athletes. The results suggest that increased training load may also negatively affect vitamin D levels in elite female indoor athletes.

Seasonal Variations in the Physical Fitness of South African Premier Soccer League Players over an Annual Training Macrocycle (Nine Months)

Article

Full-text available

Jan 2025

Background: Anecdotal data indicate that the physical fitness of soccer players fluctuates across the season. This is often a concern for coaches, since players are expected to be at optimal fitness during matches on weekly basis across the season. Objectives: To analyze the physical fitness variation in South African Premier Soccer League players over an annual training macrocycle. Methods: Twenty-four Premier Soccer League players belonging to the same team participated in the study. Players went through fitness assessments at three stages of the season: at the beginning of pre-season (T1); mid-first round in-season (T2); and mid-second round in-season (T3). The assessments included body fat percentage; sit and reach; vertical jump; 10 and 30 m sprints; and YoYo Intermittent Recovery Level 2 (YoYo IR2). Results: There was a significant increase in body fat percentage from T1 to T2 (p < 0.001), and a slight decline was evident at T3 (p = 0.04). Flexibility was significantly greater at T2 (p < 0.001) compared to T1 and T3. Vertical jump significantly improved at T3 (p = 0.004) compared to T1 and T2. A similar trend was evident in the YoYo IR2, where players reached the highest levels at T3 (p < 0.001). However, there were no significant changes in the 10 and 30 m sprints across the season. Conclusions: These results indicate that, indeed, some parameters, such as body fat percentage and flexibility, are likely to fluctuate as the season progresses. However, it is also evident that a gradual improvement can be achieved, as seen in vertical jump and YoYo IR2.

Relative Age Effect (RAE) According to Norm Values on Anthropometric Performance and Physical Fitness in 9–11-Year-Old Children

Article

Full-text available

Jan 2025

Objectives: The main purpose of this study is to identify the relative effect of age (RAE) according to norm values on the anthropometric performance and physical fitness of children between the ages of 9 and 11 years. The data, namely the percentiles of anthropometric parameters and physical fitness, are relevant for identifying the RAE in relation to gender and the month of birth in children. Methods: For the sample in this study, 1185 young people from Kosovo were enrolled, including 626 males and 559 females aged 9–11 years. The gathered data were assessed via the EUROFIT methodology, which takes into account comparisons based on the quartile of birth and the relative age effect (RAE). Results: The results of the data show us that there are significant differences in the RAE among children born in Q2 at the age of 9 years, especially in boys, as well as significant differences in the height variable at the <0.005 significance level. Others factors did not show significant differences, for example, variables that are indicators of physical fitness. For both boys and girls born in Q1, significant differences were mainly found in the indicators of explosive strength, flexibility, static strength, speed, and agility, with a level of significance of p < 0.001, while other indicators did not show significant differences. In addition, there was a significant difference the ratio between genders at the p < 0.001 and p < 0.005 levels, mainly among those born in Q1 and Q2. Similarly, at 10 years of age, children who were born earlier in the year had better scores, although the large disparities were more noticeable between quartiles than between genders, where the significant differences were mainly in the indicators of explosive strength, speed, and strength at the p < 0.001 level, as well as static strength, agility, and speed at the p < 0.005 level. Significant differences were also found for the indicators in terms of gender. At the age of 11, significant percentiles were mainly found in the quartiles at the beginning of the year for both boys and girls, and significant differences were also found at the p < 0.001 level for RAE between quartiles and gender. Conclusions: By using these data, it will be possible to highlight how males, who have demonstrated notable advantages in anthropometric and physical fitness measures, as well as those born in the first few months of the year, exhibit a relative age effect (RAE) in accordance with gender norm values.

14-16 Yaş Kız Voleybolcularda Alt Ekstremiteye Uygulanan 8 Haftalık Elastik Bantlarla Yapılan Direnç Egzersizlerinin Dikey Sıçrama ve Sürat Performansına Etkisi

Article

Full-text available

Dec 2024

Özgür AKTÜRK

Bu çalışma, elastik bantlarla yapılan direnç antrenmanların, 14-16 yaş kız voleybolcuların sürat ve dikey sıçrama performanslarına etkisini belirlemek amacıyla yapılmıştır. Voleybolculara alt eksemite kuvvetini arttıracak 10 istasyondan oluşan 8 haftalık elastik bant antrenman programı uygulandı. Katılımcılar; elastik bant grubu (EG) (n=10) ve kontrol grubu (KG) (n=12) olmak üzere randomize şekilde iki gruba ayrıldı. Katılımcıların ön testleri için antropometrik ölçümleri, dikey sıçrama ve 20 mt. sürat performansları alındı. Sekiz hafta sonra katılımcıların son testleri alınarak ölçümler tamamlandı. Elastik bant grubunun ön test ve son test verileri karşılaştırıldığında dikey sıçrama (p=0,001; p<0,05) ve vücut ağırlığı (p=0,031; p<0,05) istatiksel olarak anlamlı farklılık bulunurken 20 mt. Sürat (0.308) parametresinde istatiksel olarak anlamlı fark bulunmadı (p>0.05). EG vücut ağırlığı ön test (58,75±11,29) son test arasında (58,36±8,35) istatiksel olarak anlamlı fark bulunmuştur (p<0,05). 20 mt. sürat ön test (3,60±0,20) son test (3,54±0,24) arasında istatiksel olarak anlamlı fark bulunamamıştır (p>0,05). Antrenman grubu Dikey sıçrama ön test (29,29cm.±4,55) son test (31,67±5,24) istatiksel olarak anlamlı fark bulunmamıştır (p>0,05). KG ön test (53,37±8,35) son test (57,48±7,62) değerleri karşılaştırıldığında vücut ağırlığı (p=0,003; p<0,05) ve 20 mt. Sürat (p=0,002; p<0,05) parametresinde istatiksel olarak anlamlı farklılık bulunurken dikey sıçrama (p=0,655; p>0,05) parametresinde istatiksel olarak anlamlı farklılık bulunmadı. Vücut ağırlığı ön test (58,37±8,35) son test (57,48±7,62) değerleri ile 20 mt. Sürat ön test (3,58sn.±030) ve son test (3,64±0,29) değerleri arasında anlamlı fark bulunmuştur (p<0,05). Dikey sıçrama ön test (31,37.±3,46) son test (31,35±3,48) değerleri arasında anlamlı fark bulunmamıştır (p>0,05). EG grubu vücut ağırlığı fiziksel ve fizyolojik parametrelerine bakıldığında sporcuların vücut ağırlığının azaldığı ve grupta fiziksel farklılık düzeyinde azalma görüldüğü söylenebilir (p=0.031; p<0,05). Sürat performansında anlamlı değişiklik görülmemiştir (p=0.308; p>0,05). Dikey sıçrama parametresinde anlamlı derecede artış ve farklılaşma gözlemlenmiştir (p=0.000; p<0,05). KG vücut ağırlığı fiziksel ve fizyolojik parametrelerine bakıldığında sporcuların vücut ağırlığının ön test (58,37±8,35) son test (57,48±7,62) azaldığı ve grupta fiziksel farklılık düzeyinde azalma görüldüğü söylenebilir (p<0,05). 20mt. Sürat performansında ön test (3,58) son test (3,64) düşüş gözlemlenmiştir. Dikey sıçrama performansında anlamlı farklılık bulunmamıştır (p=0,655; p>0,05).

Enhancing Adolescent Physical Fitness and Well-Being: A School-Based High-Intensity Interval Training Program

Article

Full-text available

Dec 2024

Background: The aim of this study is to investigate the effects of a school-based high-intensity interval training (HIIT) program on quality of life and physical fitness in adolescents. Methods: The study included 60 male adolescents (16.2 ± 0.6 years), randomly assigned to one of two groups: the HIIT group (n = 30) and the control group (CG, n = 30). Participants completed the KIDSCREEN-27 questionnaire to evaluate quality of life and physical fitness tests, including vertical jump, repetitive strength, agility, and flexibility. The experimental program consisted of a 12-week intervention integrated into the warm-up phase of regular physical education (PE) classes. Each PE class lasted 45 min, with the HIIT regimen occupying 10 min of the warm-up phase. The HIIT sessions followed a Tabata-style structure, performed twice weekly. A two-way ANOVA with repeated measures assessed group and time interaction effects. Results: The results revealed changes in physical well-being following the HIIT intervention (p = 0.01) compared to the control group (p = 0.42). The results of the two-way ANOVA with repeated measures revealed interaction effects between group and time for the various fitness tests, countermovement jump (p = 0.04), 4 × 10 m agility test (p = 0.02), medicine ball throw test (p = 0.04), and sit-ups (30 s) (p = 0.01). Conclusions: This study highlights the effectiveness of school-based HIIT in significantly enhancing physical well-being and physical fitness among adolescents.

Stable or Unstable? Evaluating the Strength Outcomes of 12-Week Resistance Training in Youth Judo Athletes

Article

Full-text available

Dec 2024

Background: The purpose of this study was to compare the effects of resistance training on stable versus unstable surfaces on strength performance in young judokas. Methods: The study included 18 young judokas (age: 13.2 ± 1.2 years) with 4.7 years of training experience assigned to either the URT (unstable resistance training) group or the STG (stable resistance training) group. Both groups performed the bench press and squat exercise for 12 weeks (3 sessions/week, 30–40 min each), with one group performing on the stable surface and the other on the unstable surface. The tests included the 1RM bench press and squat, maximal power output during bench press and squat (Pmax), abdominal strength test (AB60), and the standing long jump (SLJ). Results: Statistical analyses revealed a group × time interaction for AB60 (p < 0.02) in favor of the URT group. Significant main effects of time (p < 0.01) for the 1RM bench press, 1RM squat, bench press power, AB60, and SLJ were found. There were no significant effects for squat maximal power in both groups (p ˃ 0.05). Conclusions: Both unstable and stable resistance training effectively improved maximal strength and performance in adolescent judokas, with unstable training offering additional benefits in abdominal strength.

Accuracy, precision, and sensitivity of a new contact plate for assessing vertical jump height performance

Article

Dec 2024

This study aimed to assess the accuracy, precision, and sensitivity of the Ergonauta contact plate in evaluating jump height performance in countermovement (CMJ) and squat jumps (SJ), compared to two previously validated devices (OptoJump and My Jump). Twenty-six young basketball players participated in the study. The participants positioned themselves on the Ergonauta contact plate along with the My Jump app and OptoJump optical measurement system. Three CMJs and SJs were performed, and jump height was analyzed. Intraclass correlation coefficient (ICC) and typical error (TE) were used as relative and absolute reliability indicators, respectively. The Bland-Altman plot was used to examine agreement between metrics (Ergonauta contact plate, My Jump app, and OptoJump) in CMJ and SJ, with significance set at p \ 0.05. Results demonstrated excellent relative reliability for both protocols in the Ergonauta contact plate (ICC= 0.94–0.99, TE = 1.07–1.23). Bland-Altman plots showed good agreement for the Ergonauta contact plate (CMJ and SJ) and devices (close to 0). In conclusion, the Ergonauta contact plate proved reliable and valid for assessing jump height performance, particularly in measuring jump height and mean propulsive velocity metrics

The arch myth: investigating the impact of flat foot on vertical jump height: a systematic review and meta-analysis

Article

Full-text available

Nov 2024

Objective The necessity to exclude flat foot when selecting athletes is a controversial issue. This study aimed to investigate whether flat foot affects vertical jump. Methods The quality of the literature was assessed using the observational study quality assessment tool provided by the Joanna Briggs Institute (JBI) Centre for Evidence-Based Health Care in Australia. Meta-analysis, heterogeneity testing, sensitivity analysis, subgroup analysis, and forest plot were conducted using Review Manager 5.4. Results In the end, 9 articles met the meta-analysis criteria. Due to the heterogeneity of the studies, only vertical jump height was used as an indicator for meta-analysis. Meta-analysis results showed low heterogeneity among studies (I² = 6%, P = 0.39), and the combined effect size showed no significant difference in jumping height between flat foot and normal foot (P = 0.73, ES = 0.13, 95%CI [-0.58, 0.83]). Subgroup analyses showed no significant differences in jump heights between flat and normal foot in either the adolescent subgroup (ES = 0.07, 95% CI [-1.04, 1.18]) or the adult subgroup (ES = 0.16, 95% CI [-0.76, 1.08]). Subgroups were divided according to training background, and jump height was unaffected by flat foot in both athletes (ES = -0.08, 95%CI [-1.07, 0.90]) and amateur (ES = 0.34, 95%CI [-0.67, 1.35]). Conclusion Overall, flat foot do not affect vertical jump height, although flat foot have different vertical jump biomechanics. This study breaks the bias that flat foot have poorer athletic performance. The meta-analysis has been registered with PROSPERO under registration number CRD42023481326.

Analysis and correlation of fitness and strength parameters in volleyball, basketball, and handball players of university

Article

Jan 2023

Elastic Bands During Half-Squats as A Re-Warm-Up Strategy for Youth Soccer Players' Performance

Article

Oct 2024
J SPORT SCI MED

The study aimed to assess the immediate effects of re-warm-up strategies using half-squats with elastic looped bands on the performance of youth soccer players. A cross-over study design with repeated measures was implemented in field youth male soccer players (n = 20, age 15.7 ± 0.8 years). Following the first 45-min of match play, players were subjected to one of four re-warm-up (Re-w) interventions of equal duration: no Re-w (PAS), half-squat without elastic looped bands (SQ), half-squat with bands placed on the thighs (SQT), and half-squat with bands placed on the lower legs (SQL). These interventions were compared against a control condition (CON). The Re-w protocols were initiated 10-min after half-time, and players' performance was evaluated through vertical and horizontal jump tests, 20-m linear sprint, and T-agility test. Statistical analysis using ANOVA revealed that the SQT and SQL interventions significantly improved (p < 0.001) several performance metrics compared to the PAS and SQ conditions. These improvements were observed in squat jumps, unilateral squat jumps (both dominant and non-dominant legs), countermovement jumps, horizontal jumps, triple horizontal jumps, the 20-m linear sprint, and T-agility performance. In conclusion, SQT and SQL are equally effective to enhance performance as Re-w strategies after the 1st-half of a soccer match. However, the lack of physiological data and 2nd-half assessments suggests the need for further research to confirm the persistence of these effects.

Effects of Different Stretching Modalities on the Antagonist and Agonist Muscles on Isokinetic Strength and Vertical Jump Performance in Young Men

Article

Full-text available

Oct 2024
J STRENGTH COND RES

Montalvo, S, Gonzalez, MP, Dietze-Hermosa, MS, Martinez, A, Rodriguez, S, Gomez, M, Ibarra-Mejia, G, Tan, E, and Dorgo, S. Effects of different stretching modalities on the antagonist and agonist muscles on isokinetic strength and vertical jump performance in young men. J Strength Cond Res XX(X): 000-000, 2024-Exercise warm-up may include static or dynamic stretching, impacting performance differently. This study investigated the effects of various stretching protocols on isokinetic strength, muscular activity, and vertical jump performance. Sixteen subjects, divided evenly between trained and untrained groups, underwent 8 distinct stretching conditions in random order. Outcomes measured included isokinetic knee extension and flexion torque and power, muscular activity (vastus lateralis, vastus medialis, and biceps femoris), and jump performance (jump height and modified reactive strength index [RSImod]). Responses to the stretching conditions were analyzed using a mixed-methods approach. For isokinetic knee extension, dynamic stretching of both agonist and antagonist (DY-AG-ANT) and combined dynamic agonist with static antagonist stretching (DY-AG ST-ANT) produced significant improvements. Dynamic stretching of both agonist and antagonist increased peak torque by 12.72% and average torque by 30.80%, while DY-AG ST-ANT increased peak torque by 15.61% and average torque by 41.06%. Muscular activity also improved significantly; DY-AG ST-ANT increased EMG activity of the vastus lateralis by 29.43% and vastus medialis by 70.75%. Biceps femoris saw a 33.18% increase with DY-AG and a 22.15% increase with STAG. Countermovement jump height improved with DY-AG-ANT (12.6%) and static antagonist (ST-ANT) conditions (11.3%) (p , 0.05). Dynamic stretching of both agonist and antagonist also enhanced average power knee extension by 32.41%, while STAG DY-ANT improved it by 31.09% (p , 0.05). Dynamic stretching, especially when combined with static stretching, optimizes isokinetic strength, muscular activity, and jump height. Coaches should incorporate dynamic stretching, alone or with static antagonist stretching, to maximize performance.

Effects of Different Stretching Modalities on the Antagonist and Agonist Muscles on Isokinetic Strength and Vertical Jump Performance in Young Men

Article

Full-text available

Oct 2024
J STRENGTH COND RES

Montalvo, S, Gonzalez, MP, Dietze-Hermosa, MS, Martinez, A, Rodriguez, S, Gomez, M, Ibarra-Mejia, G, Tan, E, and Dorgo, S. Effects of different stretching modalities on the antagonist and agonist muscles on isokinetic strength and vertical jump performance in young men. J Strength Cond Res XX(X): 000-000, 2024-Exercise warm-up may include static or dynamic stretching, impacting performance differently. This study investigated the effects of various stretching protocols on isokinetic strength, muscular activity, and vertical jump performance. Sixteen subjects, divided evenly between trained and untrained groups, underwent 8 distinct stretching conditions in random order. Outcomes measured included isokinetic knee extension and flexion torque and power, muscular activity (vastus lateralis, vastus medialis, and biceps femoris), and jump performance (jump height and modified reactive strength index [RSImod]). Responses to the stretching conditions were analyzed using a mixed-methods approach. For isokinetic knee extension, dynamic stretching of both agonist and antagonist (DY-AG-ANT) and combined dynamic agonist with static antagonist stretching (DY-AG ST-ANT) produced significant improvements. Dynamic stretching of both agonist and antagonist increased peak torque by 12.72% and average torque by 30.80%, while DY-AG ST-ANT increased peak torque by 15.61% and average torque by 41.06%. Muscular activity also improved significantly; DY-AG ST-ANT increased EMG activity of the vastus lateralis by 29.43% and vastus medialis by 70.75%. Biceps femoris saw a 33.18% increase with DY-AG and a 22.15% increase with ST-AG. Countermovement jump height improved with DY-AG-ANT (12.6%) and static antagonist (ST-ANT) conditions (11.3%) ( p < 0.05). Dynamic stretching of both agonist and antagonist also enhanced average power knee extension by 32.41%, while ST-AG DY-ANT improved it by 31.09% ( p < 0.05). Dynamic stretching, especially when combined with static stretching, optimizes isokinetic strength, muscular activity, and jump height. Coaches should incorporate dynamic stretching, alone or with static antagonist stretching, to maximize performance.

"Effectiveness Of Dynamic Neuromuscular Stabilization (DNS) On Physical Performance In College-Level Athletes"

Article

Full-text available

Aug 2024

Background: College-level athletes often face unique challenges in maintaining optimal physical performance while balancing academic and athletic responsibilities. Neuro musculoskeletal dysfunctions are common in this population and can impair performance and increase injury risk. Dynamic Neuromuscular Stabilization (DNS) is an innovative therapeutic approach based on developmental kinesiology principles. It aims to restore ideal postural and movement patterns, enhance core stability, and optimize neuromuscular control. This study investigates the effectiveness of an 8-week DNS training program on key physical performance metrics among college-level athletes. Methods: This quasi-experimental study included 30 college-level athletes aged 18-25, who were divided into two groups: the DNS group (n=15) and a control group (n=15). Participants in the DNS group underwent an 8-week training program focusing on exercises designed to activate deep stabilizing muscles, improve proprioception, and optimize movement patterns. The control group continued their usual training regimen without specific DNS interventions. The primary outcome measures were vertical jump height (VJT) and dynamic balance, assessed using the Y Balance Test (YBT). Pre- and post-intervention assessments were conducted, and data were analyzed using paired t-tests and ANOVA to determine the intervention's effectiveness. Results: The DNS group demonstrated significant improvements in both VJT and YBT scores compared to the control group (p < 0.05). Specifically, the DNS group showed a mean increase in VJT of 4.2 cm and a significant enhancement in dynamic balance, with improvements in all directions measured by the YBT. The control group exhibited minimal changes in these performance metrics. These findings suggest that DNS training effectively enhances explosive power and dynamic stability, critical components of athletic performance. Conclusion: The study provides empirical evidence supporting the use of DNS as an effective training modality for enhancing physical performance in college-level athletes. The improvements observed in vertical jump height and dynamic balance suggest that DNS can play a pivotal role in optimizing athletic performance and potentially reducing the risk of injury. The study's findings have practical implications for sports physiotherapy and athletic training programs, recommending the integration of DNS techniques into standard training protocols. Keywords: Dynamic Neuromuscular Stabilization, DNS, athletic performance, college athletes, vertical jump, dynamic balance, sports physiotherapy, core stability.

The effect of percussion and manual activation massage on explosive strength and balance in young adult males: A crossover pilot study

Article

Full-text available

Oct 2024

Background Recently, the usage of percussive vibration machines in physiotherapy and sports has increased rapidly. Numerous manufacturers claim they can enhance physical performance. However, there is minimal peer-reviewed research on their efficacy. Therefore, this study aimed to investigate the effect of percussion massage (PM) on muscular performance, particularly explosive strength and balance. Moreover, this is the first study to evaluate the potential PM impact on balance. Materials and methods 18 young male participants aged 20.89 ± 3.43 years with a BMI of 25.08 ± 3.95 completed three measurements with two interventions - PM by Theragun device (TG), activation massage (AM), and assessment without activation (WA). The targeted area was m. triceps surae, hamstrings, and m. quadriceps femoris of the dominant leg. Single-leg squat jump (SJ), countermovement jump (CMJ), and Y-balance tests (YBT) were performed. One-Way Repeated Measures ANOVA was utilized to analyze the data. The level significance threshold was set to p ≤ 0.05. Results No statistically significant difference was reported between TG, AM, and WA in the height of the squat jump and countermovement jump (p > 0.05). Furthermore, no significant changes were recorded in the YBT performance score (p > 0.05). Conclusions No improvement was reported in the monitored physical parameters when the PM by Theragun or manual AM was applied for 90 s right before the muscular performance. Therefore, we do not recommend the short-term stimulative application of PM and AM before athletic performance when lower limb explosive strength or balance improvements are the objective.

Relationship between Repeated Sprint Ability and Force–Velocity Profile in Elite and Subelite Female Field Hockey Players

Article

Full-text available

Oct 2024

Featured Application This study suggests that the force–velocity profile conceived by Bosco could be a useful, easy-to-apply assessment method of athletes’ level of performance. Furthermore, the control of the step length and step frequency enables coaches and athletes to develop RSA training with a more specific focus based on the specific improvement needs (e.g., wicket run). Abstract This study aimed to compare two female field hockey teams of different competitive levels by analyzing kinematic variables in repeated sprint ability (RSA) tests and the force-velocity profile (FVP). Twenty-five female hockey players representing the elite and subelite levels from the same club volunteered to participate. The RSA protocol included six 30 m maximal sprints with a 30 s recovery. Kinematic variables, such as sprint time, step frequency, and step length, were analyzed for each sprint. Additionally, players performed counter-movement jumps (CMJs) and CMJs with 50% body weight (CMJ50s) to calculate the FV50 using the Bosco Index. The elite players showed better (≈2%; p < 0.05) fatigue indexes in sprint time (0–30 m and 0–10 m sections), step length (0–10 m, 10–20 m, and 20–30 m sections), and step frequency (20–30 m section) during the RSA test, as well as greater values (>10%; p < 0.05) in the CMJ50 and FV50 tests. In addition, these RSA (sprint time, step frequency, and step length) and jumping (CMJ, CMJ50, and FV50) variables showed a moderate, significant, or very significant relationship with each other. Therefore, it seems that both strength and speed capacities can be used either in conjunction or as a complementary approach to enhance the overall RSA performance.

Longitudinal comparison of the relationship of energy intake with body composition and physical performance in elite female basketball and volleyball players

Article

Full-text available

Oct 2024
Sport Sci Health

Purpose To maximise sporting success, disciplines such as basketball and volleyball need to improve their methods of analysing the sporting performance and fitness of their athletes. Although energy intake quantities have been established at a theoretical level for women to perform at a sporting level, it has been found that these energy intake levels are not met or followed and that, despite this, the performance of female players is not diminished. Thus, the purpose of this research study was to describe and compare the anthropometric characteristics of these two disciplines and to identify the differences in actual and theoretical energy intake, as well as to observe physical performance in both disciplines. Methods Anthropometric data, continuous quantitative data, training time and characteristics, and energy intake data were collected. Performance tests included upper and lower body strength, speed, agility, and endurance tests. Dietary monitoring showed lower intakes of total energy, carbohydrate and protein than theoretically recommended. However, the athletes experienced overall improvements in performance and body composition. Results The mean total energy intake was 20.2 ± 4.3 kcal·kg⁻¹·day⁻¹. The minimum individual mean intake was 9.8 kcal·kg⁻¹·day⁻¹ and the maximum was 25.95 kcal·kg⁻¹·day⁻¹. Carbohydrates accounted for 54.3% ± 8.8% of the energy intake; 20.3% ± 6.5% from fats; 25.4% ± 5.7% from proteins. Conclusions Current data suggest that, although a cause-effect relationship between dietary intake and BC performance cannot be determined, elite athletes in these sports disciplines may experience beneficial outcomes despite having lower total energy, CHO, protein, and fat intakes than previously recommended in the literature.

Are physiological, physical, wellness and load decisive markers of starting players? A case study from a professional male soccer team

Article

Full-text available

Sep 2024
AM J MENS HEALTH

The study aim was to compare physiological, physical, accumulated wellness and load markers within a European professional soccer team between starters and non-starters. Ten starters (age: 25.1 ± 2.2 years; experience: 7.3 ± 2.3 years) and eight non-starters (age: 26.1 ± 4.6; years' experience: 8.3 ± 4.1 years) participated in the study. The study was conducted across 20 weeks where 75 training sessions and 15 matches occurred. Wellness (fatigue, quality of sleep, muscle soreness, stress and mood) and load (rating of perceived exertion (RPE), accelerations, decelerations, high-speed running and sprinting) measures were observed. Physiological evaluation consisted of a 1200 m maximum effort shuttle test while physical capacity assessment included isokinetic strength, jump ability and balance tests. Isokinetic tests were used to assess peak torque of both legs (extension and flexion at 60 • /s and 180 • /s), single squat jump and single hop jump were utilized to assess jump ability and Y-balance tests were employed to examine balance. Starters presented significantly higher values for peak torque extension of the non-dominant leg compared to non-starters (p = 0.038, effect size (ES) = 0.996), while non-starters showed higher values for both Y-balance postero-medial and postero-lateral (p = 0.009, ES = −1.309 and p = 0.021, ES = −1.133, respectively). Accumulated duration and RPE were lower for non-starters than starters (p ≤ 0.001, ES = 1.268, and p = 0.022, ES = 1.123, respectively). The physiological and physical tests conducted in this study do not seem to determine the starting status of players, considering that only one test revealed significantly higher values for starters. Despite the lower training and match duration for non-starters, this showed that it is possible to accumulate identical load while managing wellness regardless of starting status.

Predictive Models of Hamstring Performance in Adolescent Athletes

Article

Mar 2025

This study investigated the relationships between hamstring strength, flexibility, core endurance, jumping performance, single-leg bridge endurance, and knee joint range of motion (ROM) across six sports disciplines, including football, swimming, volleyball, karate, wrestling, and athletics. A total of 249 athletes (144 men, 105 women) aged 10–18 years participated, with a mean BMI of 22,6 kg/m² and an average of 4.9 years of sports experience. Regression analyses revealed sport-specific predictors of performance and injury risk. Dominant hamstring strength and torque were strong predictors of explosive move-ments like squat jumps in football (R²=0.74, p

Analysis of Musculoskeletal Injuries in Elite Female Soccer Players: cohort study in one Brazilian Team

Article

Feb 2025
PHYS THER SPORT

A Study of Lower Limb Explosiveness in 17 College Students: A Comparison of CMJ and CMJS Movements

Article

Jan 2025

梦强余

The effects of a 6-week sand- vs. Land-based jump training programme on frontal plane knee angle and jump performance in adolescent female football players*

Article

Feb 2025
J SPORT SCI

The relationship of body composition and motor abilities of female basketball players

Conference Paper

Jan 2025

Success in the basketball game does not only require technical, tactical and psychological abilities, but also depends on body composition and motor abilities. The motor abilities that contribute most to success in basketball are explosive power, agility with and without the ball, and speed of cyclic or acyclic movements. Given that body composition and motor abilities are the basis for every sport, the aim of this study is to determine whether there is a connection between body composition and motor abilities of female basketball players. The sample of respondents consisted of female basketball players who play in the cadet league, with an average chronological age of 15.08 ± 0.94 years, who trained volleyball for an average of 5.93 ± 2.46 years. First, the subjects' body composition parameters were measured (body height, body mass, body mass index (BMI), fat percentage (BF), muscle percentage (Muscle%), followed by agility tests (T-test, Slalom, Slalom with ball), speed (5m, 10m and 20m sprint), and explosive power (Counter Movement Jump (CMJ), Counter Movement Jump With Arm Swing (CMJwas), Squat Jump (SJ)). The results showed that there is a relationship between the parameter BH with CMJ, CMJwas and SJ, then BW with CMJ, 20m and Slalom. Furthermore, BMI was correlated with CMJ and Slalom, and the parameters BF% and Muscle % with the motor abilities of explosive power, speed and agility. Based on the obtained results, it can be conclude that there is a statistically significant correlation between body composition parameters and motor abilities of female basketball players.

USABILITY OF ISOTONIC DYNAMOMETRY TESTING IN CHILDREN AND YOUTH

Article

Full-text available

Dec 2024

This study aims to investigate the usability of isotonic dynamometry in children and youth by determining the correlation between isometric dynamometry, which is considered the most valid direct-laboratory method for the assessment of muscle contractile properties in children, and isotonic dynamometry. The sample of the participants was composed of children and youth aged 7 to 19 years divided into 3 groups: younger school age (7-10 y), middle school age (11-14 y) and high school age (15-19 y). Implemented tests were the hand grip strength test (isometric dynamometry) and countermovement jump on the force plates (isotonic dynamometry). The results of Pearson’s correlation coefficient revealed that there is no significant correlation between Fmax, RFD and jump height in younger (r = 0.176, p = 0.291; r = 0.152, p = 0.363, respectively) and middle school-age children (r = 0.059, p = 0.733; r = 0.201, p = 0.241, respectively) while there is a high correlation in the group of high school participants (r = 0.531, p = 0.001; r = 0.544, p = 0.001, respectively). This study's results indicate that the isotonic dynamometry method is not valid for implementation in the group of children under the age of 15.

Test–retest reliability of strength, power, agility, and sprint performance in female team handball players

Article

Full-text available

Nov 2024
J SCI MED SPORT

Horizontal Sıçramanın Değerlendirilmesinde Myjump 2 Uygulamasının Geçerliği ve Güvenirliği: Test Tekrar Test Çalışması

Article

Full-text available

Nov 2024

Yatay sıçrama, özellikle atletizm, basketbol ve futbol gibi sporlarda sporcuların patlayıcı gücünü ve performansını belirlemede kritik bir rol oynamaktadır. Bu çalışmanın amacı, MyJump 2 uygulamasının üniversite sporcularının yatay sıçrama performansını değerlendirmedeki geçerlilik ve güvenilirliğini incelemektir. Çalışma, nicel araştırma yöntemlerinden korelasyonel araştırma deseni kullanılarak tasarlanmıştır. Araştırmaya Burdur Mehmet Akif Ersoy Üniversitesi Spor Bilimleri Fakültesi’nde en az bir yıl lisanslı spor yapmış 40 öğrenci katılmıştır. Yatay sıçramalar, MyJump 2 uygulaması ile geleneksel şerit metre kullanılarak eş zamanlı olarak ölçülmüştür. Veriler, Jamovi paket programı ile analiz edilmiştir. Normallik versayımı Shapiro Wilk testi ile control edilmiştir. Pearson korelasyon katsayısı analizi ile geçerlik değerlendirilirken, sınıf içi korelasyon katsayııs analizi (ICC) ile güvenirlik değerlendirilmiştir. Pearson korelasyon analizi sonuçlarına göre, MyJump 2 ile şerit metre arasında mükemmel bir geçerlik bulunmuştur (r = 0.99). Bland Altman analizi sonuçları ise MyJump 2’nin sadece 0.42 cm'lik bir ortalama yanlılık gösterdiğini ortaya koymuştur. Test-tekrar test güvenilirliği ise sınıf içi korelasyon katsayısı (ICC) ile değerlendirilmiş ve oldukça yüksek bir güvenilirlik tespit edilmiştir (ICC = 0.99). Bu bulgular, MyJump 2 uygulamasının, spor bilimlerinde ve antrenman programlarında kullanılabilecek güvenilir ve geçerli bir araç olduğunu göstermektedir. Ayrıca, MyJump 2’nin taşınabilir ve düşük maliyetli olması, pahalı laboratuvar ekipmanlarına erişimi olmayan antrenörler ve sporcular için pratik bir alternatif sunmaktadır. Bu sayede alan uzmanları, MyJump 2'yi saha koşullarında yatay sıçrama performansını değerlendirmek için etkili bir ölçüm aracı olarak kullanabilirler.

The effects of structured coordinative exercise protocol on physical fitness, motor competence and inhibitory control in preschool children

Article

Full-text available

Nov 2024

The aim of the study was to evaluate the effects of a structured coordinative exercise intervention based on motor skill elements on physical fitness (PF), motor competence (MC) and inhibitory control (IC) in preschool children. A total of 41 kindergarten children (27 boys and 17 girls) aged between 5 and 6 years participated and were divided into exercise (EG; n = 18) and control (CG; n = 23) groups. The exercise group participated in a structured coordinative exercise programme focusing on locomotor and balance skills such as side-stepping, galloping, jumping and running for 30 min, 2 days a week for 8 weeks. The control group followed the normal curriculum. Children participated in measurements before and after 8 weeks, respectively; motor competence was assessed using the Körperkoordinationstest für Kinder (KTK3+) test battery, which includes eye-hand coordination and other coordinative skills. Physical fitness was measured by balance, agility and vertical jump tests. Inhibitory control was assessed using the Go/NoGo test in the Early Years Toolbox. As a result of the two-factor analysis of variance for mixed measures to determine whether being in the exercising group had a significant effect on the test scores, group by time interaction effect showed that the increase in the scores of the exercise group was significantly higher than that of the control group in the parameters of static balance, KTK sideways jump and KTK eye-hand coordination [respectively: F(1−39) = 6.993, p = 0.012; 6.443, p = 0.015; 8.180, p = 0.007). The results show that structured coordinative exercises improve PF and MC but have no significant effect on IC. This study targets the development of motor and cognitive skills considered to be important in preschool children and is one of the few studies to evaluate these parameters simultaneously. It also provides a comprehensive perspective on interventions aimed to positively affect health and development in early childhood. Trial Registration: NCT06631248. Registered on October 07, 2024.

Proteomic analysis reveals biomarkers associated with performance-based joint function and patient-reported outcomes in knee osteoarthritis

Article

Nov 2024

Objective This study aimed to identify proteins associated with clinical manifestations of knee osteoarthritis (KOA), including performance-based joint function and patient-reported outcome measures (PROM). Methods This cross-sectional exploratory study included thirteen individuals with KOA and eleven age-matched controls. All participants performed the 30s Single Leg Mini Squat test and 30s Sit-to-Stand test with simultaneous recording of joint kinematics. Individuals with KOA completed the Knee Injury and Osteoarthritis Outcome Score and Forgotten Joint Score-12. Proteins were determined by quantitative mass spectrometry (MS) in plasma. Principal component analysis (PCA), hierarchical cluster analysis (HCA), and Reactome enrichment analysis of the proteome were conducted to identify activated pathways and groups. Results Performance-based function was worse in individuals with KOA compared to controls, and they reported higher levels of pain. MS analysis identified 82 differentially expressed proteins (DEPs) in KOA (28 upregulated, 54 downregulated of 321 detected proteins). PCA displayed distinct features between KOA and controls, similar to HCA, which distinguished two major clusters. Enrichment analysis displayed platelet activation and degranulation, neutrophil, and extracellular matrix (ECM)-related pathways. From the proteome, 23 DEPs were associated with different aspects of joint function, and 25 DEPs with PROM. Conclusions Individuals with KOA differed from controls across all three assessment modalities; they presented worse joint function, higher levels of pain, and an altered plasma protein profile. Multiple associations were observed between up- and downregulated DEPs and clinical manifestations. The described study protocol shows promise for performing multivariate analyses for future subgrouping of individuals with KOA.

Vertical-jump Tests: A Critical Review

Article

Full-text available

Oct 2000

Peter Klavora

Research Methods in Physical Activity

Chapter

Full-text available

Jan 1996

An evaluation of the specificity, validity and reliability of jumping tests

Article

Full-text available

Dec 1997

There were three objectives of this study: 1. To describe the influence of using a single and double leg take-off as a function of run-up length in jumping for height. 2. To determine if various types of jumps are specific in nature. 3. To evaluate two methods of assessing jumping height (a modified Vertec or Yardstick and a Board) for validity and inter-day reliability. Seventeen male subjects were tested on jumps for height from a standing position and using a 1, 3, 5 and 7 stride run-up. These jumps were performed using a single and double leg take-off measured by the Yardstick. Selected jumps were also tested using a Board method and repeated for assessment of reliability. The single leg take-off produced significantly higher jumps when the run-up was three or more strides. The inter-relationships among jump conditions were generally high, however jump types could be considered as specific when the run-up length and number of legs used in the take-off were different. The Yardstick produced significantly greater jump heights than the Board method, which questions the validity of using a board for assessment of maximum jump performance. The reliability of both methods was generally high however the jumps performed from a run-up produced less reliable results than the standing jumps for the Yardstick. It was suggested that the design of tests to assess jumping ability should consider the specific jump type used in the sport of interest and that the Yardstick is the preferred mode of testing, provided that attempts are made to maximise reliability.

Comparison of the Vertec and Just Jump Systems for Measuring Height of Vertical Jump by Young Children

Article

Full-text available

May 1998
PERCEPT MOTOR SKILL

Larry D. Isaacs

To assess differences between the Vertec and the Just Jump Systems in measuring height of vertical jump, 248 boys and 232 girls between 7 and 11 years were required to perform four maximal countermovement vertical jumps. A maximum of the four trials recorded was the dependent variable. Each vertical jump was simultaneously evaluated by each measuring device and a paired t test indicated the systems were significantly different; however, the experimentwise difference of .93 in. has no practical value. The Just Jump System seems a viable alternative. Advantages and potential pitfalls regarding the use of each system are discussed.

Literature review: Explosive exercises and training

Article

Jun 1993

Michael Henry Stone

The physical test of a man

Article

Jan 1921

D.A. Sargent

Evaluation of Explosive Strength for Young and Adult Athletes

Article

Mar 1988

Jukka T. Viitasalo

The explosive strengths of young (n = 361) and adult (n = 10) male athletes were evaluated by a vertical jumping and a ball-throwing test. The young athletes ranged in age from 10 to 16 years representing seven different sports events: track and field, apparatus gymnastics, basketball, ice hockey, orienteering, skiing, and wrestling. The adults subjects were volleyball players. Weighted vertical counter-movement jumps were performed on a platform connected to an electronic unit which calculated the height of the rise of the body's center of gravity. For the stationary ball throwing test, horizontal throwing velocity was measured for balls of different masses by an electrical apparatus. In addition to the new jumping and throwing tests a subgroup of 48 track and field athletes were measured doing jump and reach, standing broad jump, and throwing distance tests. The new jumping test was found to give reliable results from 11-12 years of age and older while the throwing test results were reliable at 10 years of age. Interevent differences in reliability were minor in the throwing test while, in the jumping test, apparatus gymnasts achieved the most reliable results and the wrestlers the least reliable results. The reliabilities for throwing lighter objects and jumping with lighter loads were better than for the heavier objects and loads, as measured by the coefficient of variation. The results of the new jumping and throwing tests showed rather high correlations (r = .66 - .82), as compared with the respective traditional field tests.

Does Elastic Energy Enhance Work and Efficiency in the Stretch-Shortening Cycle?

Article

Nov 1997

This target article addresses the role of storage and reutilization of elastic energy in stretch-shortening cycles. It is argued that for discrete movements such as the vertical jump, elastic energy does not explain the work enhancement due to the prestretch. This enhancement seems to occur because the prestretch allows muscles to develop a high level of active state and force before starting to shorten. For cyclic movements in which stretch- shortening cycles occur repetitively, some authors have claimed that elastic energy enhances mechanical efficiency. In the current article it is demonstrated that this claim is often based on disputable concepts such as the efficiency of positive work or absolute work, and it is argued that elastic energy cannot affect mechanical efficiency simply because this energy is not related to the conversion of metabolic energy into mechanical energy. A comparison of work and efficiency measures obtained at different levels of organization reveals that there is in fact no decisive evidence to either support or reject the claim that the stretch- shortening cycle enhances muscle efficiency. These explorations lead to the conclusion that the body of knowledge about the mechanisms and energetics of the stretch-shortening cycle is in fact quite lean. A major challenge is to bridge the gap between knowledge obtained at different levels of organization, with the ultimate purpose of understanding how the intrinsic properties of muscles manifest themselves under in-vivo-like conditions and how they are exploited in whole-body activities such as running. To achieve this purpose, a close cooperation is required between muscle physiologists and human movement scientists performing inverse and forward dynamic simulation studies of whole-body exercises.

Storage of Elastic Energy in Skeletal Muscles in Man

Article

Jul 1974
Acta Physiol Scand

The question, if muscles can absorb and temporarily store mechanical energy in the form of elastic energy for later re-use, was studied by having subjects perform maximal vertical jumps on a registering force-platform. The jumps were performed 1) from a semi-squatting position, 2) after a natural counter-movement from a standing position, or 3) in continuation of jumps down from heights of 0.23, 0.40, or 0.69 m. The heights of the jumps were calculated from the registered flight times. The maximum energy level, Eneg, of the jumpers prior to the upward movement in the jump, was considered to be zero in condition 1. In condition 2 it was calculated from the force-time record of the force-platform; and in condition 3 it was calculated from the height of the downward jump and the weight of the subject. The maximum energy level after take-off, Ep0s, was calculated from the height of the jump and the jumper's weight. It was found that the height of the jump and Epos increased with increasing amounts of Eneg, up to a certain level (jumping down from 0.40 m). The gains in Epos over that in condition 1, were expressed as a percentage of Eneg and found to be 22.9 % in condition 2, and 13.2, 10.5, and 3.3 % in the three situations of condition 3. It is suggested that the elastic energy is stored in the active muscles, and it is demonstrated that the muscles of the legs are activated in the downward jumps before contact with the platform is established.

Developing Explosive Muscular Power: Implications for a Mixed Methods Training Strategy

Article

Oct 1994

Contribution of Arm Movement to the Force Components of a Maximum Vertical Jump

Article

Feb 1989

Vertical jump is used commonly as a measure of leg power for evaluation prior to participation in sports activities (RK Gray, KB Start, DJ Glencross, Res Q 33:230-235, 1962; DO Klotz, Doctoral dissertation, University of Iowa, 1948). Unless vertical jump meets the definition of mechanical leg power, it should not be used as a measure of leg power. Measurement of leg power in a vertical jump should not be started with a countermovement of the arms prior to jumping. The purpose of this research was to investigate the kinetic and kinematic contributions of arm movement to the vertical jump. Eighteen subjects performed three vertical jumps on a force platform with arm movement and three jumps without arm movement. The contribution of arm movement to maximum force, work done, power, and the release velocity was found as 6, 14, 15, and 6%, respectively, for this population. The contribution of the arm action to reduce the impact force was 12%. The contribution of arm movement to vertical jump maximum force in this study was less than reported in previous studies. J Orthop Sports Phys Ther 1989;11(5):198-201.

Potentiation of the mechanical behavior of the human skeletal muscle through prestretching

Article

Sep 1979

Force-velocity and power-velocity curves in a vertical jump involving movements around several joints were derived from vertical ground reaction forces and knee angular velocities. The jumps were performed with weights from 10 to 160 kg added on the shoulders. The obtained curves from a semi-squatting static starting position resembled those reported for isolated muscles or single muscle groups. Vertical jumps were also performed in the conditions where the shortening of the leg extensors was preceded by prestretching of the active muscles either through a preparatory counter-movement or dropping down on the force-platform from the various heights ranging from 20 to 100 cm. Prestretching modified through a range of velocities the force-velocity and power-velocity curves by increasing both the ground reaction forces and the calculated mechanical power. Thus the results are similar to those reported in isolated muscles. In studies with isolated muscle preparation the nervous connections have not been intact and therefore it is suggested that increase in the performance of the skeletal muscles through prestretching, in the conditions of the present study, was attributed to the combined effects of the utilization of stored elastic energy and the reflex potentiation of muscle activation.

Segmental contribution to forces in vertical jump

Article

May 1978
Eur J Appl Physiol Occup Physiol

Performance of a vertical jump was analyzed with respect to the contribution of the different body segments to the forces acting on the whole body center of gravity. Both cinematograph and force-platform techniques were employed. The data disclosed that the take-off velocity in vertical jumps was caused by the different components as follows: knee extension 56%, plantar flexion 22%, trunk extension 10%, arm swing 10%, and head swing 2%. However, the average take-off velocity of the total performance (3.03 m/s) was only 76% from the theoretical maximum calculated from the segmental analyses. Optimal timing of the segmental performances was calculated to increase this "efficiency" to 84%. Great variance were observed among individuals in the total performance despite the similarities in utilization of the performance of individual segments.

Utilization of stored elastic energy in leg extensor muscles by men and women

Article

Feb 1978
Med Sci Sports

An alternating cycle of eccentric-concentric contractions in locomotion represents a sequence when storage and utilization of elastic energy takes place. It is possible that this storage capacity and its utilization depends on the imposed stretch loads in activated muscles, and that sex differences may be present in these phenomena. To investigate these assumed differences, subjects from both sexes and of good physical condition performed vertical jumps on the force-platform from the following experimental conditions: squatting jump (SJ) from a static starting position; counter-movement jump (CMJ) from a free standing position and with a preparatory counter-movement; drop jumps (DJ) from the various heights (20 to 100 cm) on to the platform followed immediately by a vertical jump. In all subjects the SJ, in which condition no appreciable storage of elastic energy takes place, produced the lowest height of rise of the whole body center of gravity (C.G.). The stretch load (drop height) influenced the performance so that height of rise of C. of G. increased when the drop height increased from 26 up to 62 cm (males) and from 20 to 50 cm (females). In all jumping conditions the men jumped higher than the women. However, examination of the utilization of elastic energy indicated that in CMJ the female subjects were able to utilize most (congruent to 90%) of the energy produced in the prestretching phase. Similarly, in DJ the overall change in positive energy over SJ condition was higher in women as compared to men. Thus the results suggest that although the leg extensor muscles of the men subjects could sustain much higher stretch loads, the females may be able to utilize a greater portion of the stored elastic energy in jumping activities.

Body configuration and joint moment analysis during standing long jump in 6-yr-old children and adult males

Article

Oct 1991

The purpose of the present study was to compare the body configurations and the joint function during standing long jump in 6-yr-old children and adult males. Twelve healthy adult males and eight (one male and seven females) 6-yr-old kindergartners participated in this study. Subjects performed standing long jump on a force platform with full effort. Body segment and joint angles were analyzed by high speed videography (100 frames.s-1). Using kinetic and kinematic data, joint moments, power, and work done were calculated through a free body diagram. Average standing long jump performances were +1.5 SD above Japanese norm in both adults and children. A wide range of motion of the lower limb segments during flight phase was found in the adults. In the crouch prior to take off, joint muscle power peaks appeared in the same order, and joint contribution to the total work done showed almost the same values in both adults and children. It is suggested that gross motor pattern before take off is almost accomplished by the 6-yr-old. Judging by hip joint work, adult performance was much better than that of children, since the adults exerted relatively higher negative work from the onset of preparatory movement to the point of lowest center of gravity during crouch. It was concluded that skilled 6-yr-old children have not fully developed either hip negative work during preparatory movement or body configuration in the flight phase, although gross motor pattern before take off phase was accomplished to skilled adult level.

The effects of arms and countermovement on vertical jumping

Article

Jun 1991

Countermovement and arm-swing characterize most jumping. For determination of their effects and interaction, 18 males jumped for maximal height from a force platform in all four combinations of arm-swing/no-arm-swing and countermovement/no-countermovement. For all jumps, vertical velocity peaked 0.03 s before and dropped 6-7% by takeoff. Peak positive power averaged over 3,000 W, and occurred about 0.07 s before takeoff, shortly after peak vertical ground reaction force (VGRF) and just before peak vertical velocity. Both countermovement and arm-swing significantly (P less than 0.05) improved jump height, but arm-swing's effect was greater, enhancing peak total body center of mass (TBCM) rise both pre and posttakeoff. Countermovement only affected the post-takeoff rise. The arm-swing resulted in higher peak VGRF and peak positive power. During countermovement, the use of arms resulted in less unweighting, slower and less extensive TBCM drop, and less negative power. Countermovement increased pretakeoff jump duration by 71-76%, increased average positive power, and yielded large positive and negative impulses. High test-retest reliability was shown for jump descriptive variables. Body weight together with peak posttakeoff TBCM rise effectively predicted peak power (multiple R2 = 0.89, standard error of estimate = 243 W). The results lend insight into which jumping techniques are most appropriate for given sports situations and indicate that a jump test can effectively be used to estimate peak power output.

Simple Tests for Surveying Muscle Strength and Muscle Stiffness in Sportsmen

Article

Mar 1987

Thirty-nine elite runners were examined by Cybex II for thigh muscle strength. In addition, the maximal abduction, flexion and extension in the hip, dorsal flexion in the ankle, standing five steps, long and vertical jump, and side and front split were measured. For the latter five tests, an ordinary measuring tape was used. To establish reference values, 111 district level runners and 24 keep-fit joggers were examined by the three jump tests and the side and front split. Twenty randomly selected runners were examined twice to determine the reproducibility. The mean CV% was 1.9±1.4. There was a statistically significant correlation between the results in the vertical jump, the standing five steps, and long jump and muscle strength (P < 0.001), in particular as to the values in the higher angle velocity. Furthermore, there was a correlation (P < 0.001) between the results in side and front split and the hip. There was a covariation between the three ranges of motion, suggesting that stiffness in the hip was a general condition involving all directions of movements. The sensitivity for the jump tests and the side/front splits was 75%-91%. The specificity for the same test varied between 70% and 100%.

Potentiation of myoelectrical activity of human muscles in vertical jumps

Article

Jan 1983
Electromyogr Clin Neurophysiol

The electro-mechanical behaviour of five lower limb muscles was studied in six male students during vertical jumping on force platform. The jumps were performed (1) from a static squatting position (SJ), (2) with counter-movement (CMJ) and (3) after dropping (DJ) from five different heights. Electromyographic (EMG) activity recorded from mm. gluteus maximus, rectus femoris, vastus lateralis, vastus medialis and gastrocnemius showed an increase during the eccentric phase of contact in the CMJ and DJ conditions when compared to the activity during the squatting jumps. This was suggested as being due to reflex activity at the supraspinal level. The potentiation of EMG integral (IEMG) showed intermuscular and interindividual variations. The former was attributed to variations in mechanical positions and the preactivity of the muscles during the jumping performance, and the latter to variations in training status and/or in muscle structure. The reproducibility of IEMG, force and jumping height measurements expressed as correlation coefficients between duplicate measurements were .79, .90 and .97, respectively, showing the experimental design as acceptable for further studies of the function of the neuromuscular system in jumping performance.

Influence of aging on the mechanical behavior of leg muscles

Article

Feb 1980
Eur J Appl Physiol Occup Physiol

Age dependence of the mechanical behavior of leg extensor muscle was investigated using vertical jumps with and without a stretch-shortening cycle on the force-platform. A total 226 subjects (113 females and 113 males) ranging in age from 4--73 years were examined. The results indicated in general that performance in males was better than that in females. This difference was reduced when body weight was taken into consideration. The peak performance of the various parameters, such as average force, height of rise of center of gravity, net impulse, and also the average power output, was reached in both sexes between the ages of 20 and 30 years. For example, the average vertical force in squatting had the following mean values in the various age groups of the male subjects: 114N (4--6 years), 402N (13--17), 618N (18--28), 508N (29--40), 435N (41--49), 320N (54--65), 315N (71--73 years). When the jumps were performed using the stretch-shortening cycle, the potential of the mechanical performance after prestretching was also sensitive to aging in a similar manner. The results suggest that it is not only the performance of pure concentric contraction that is influenced by the maturation and aging processes but, the that elastic behavior of muscle and reflex potentiation are also affected by the same processes.

The optimal training load for the development of dynamic athletic performance

Article

Dec 1993

This study was performed to determine which of three theoretically optimal resistance training modalities resulted in the greatest enhancement in the performance of a series of dynamic athletic activities. The three training modalities included 1) traditional weight training, 2) plyometric training, and 3) explosive weight training at the load that maximized mechanical power output. Sixty-four previously trained subjects were randomly allocated to four groups that included the above three training modalities and a control group. The experimental groups trained for 10 wk performing either heavy squat lifts, depth jumps, or weighted squat jumps. All subjects were tested prior to training, after 5 wk of training and at the completion of the training period. The test items included 1) 30-m sprint, 2) vertical jumps performed with and without a countermovement, 3) maximal cycle test, 4) isokinetic leg extension test, and 5) a maximal isometric test. The experimental group which trained with the load that maximized mechanical power achieved the best overall results in enhancing dynamic athletic performance recording statistically significant (P < 0.05) improvements on most test items and producing statistically superior results to the two other training modalities on the jumping and isokinetic tests.

Why is countermovement jump height greater than squat jump height?

Article

Dec 1996

In the literature, it is well established that subjects are able to jump higher in a countermovement jump (CMJ) than in a squat jump (SJ). The purpose of this study was to estimate the relative contribution of the time available for force development and the storage and reutilization of elastic energy to the enhancement of performance in CMJ compared with SJ. Six male volleyball players performed CMJ and SJ. Kinematics, kinetics, and muscle electrical activity (EMG) from six muscles of the lower extremity were monitored. It was found that even when the body position at the start of push-off was the same in SJ as in CMJ, jump height was on average 3.4 cm greater in CMJ. The possibility that nonoptimal coordination in SJ explained the difference in jump height was ruled out: there were no signs of movement disintegration in SJ, and toe-off position was the same in SJ as in CMJ. The greater jump height in CMJ was attributed to the fact that the countermovement allowed the subjects to attain greater joint moments at the start of push-off. As a consequence, joint moments were greater over the first part of the range of joint extension in CMJ, so that more work could be produced than in SJ. To explain this finding, measured and manipulated kinematics and electromyographic activity were used as input for a model of the musculoskeletal system. According to simulation results, storage and reutilization of elastic energy could be ruled out as explanation for the enhancement of performance in CMJ over that in SJ. The crucial contribution of the countermovement seemed to be that it allowed the muscles to build up a high level of active state (fraction of attached cross-bridges) and force before the start of shortening, so that they were able to produce more work over the first part of their shortening distance.

Maximal and explosive force production capacity and balance performance in men of different ages

Article

Feb 1999
Eur J Appl Physiol Occup Physiol

A group of 32 healthy men (M) divided into three different age groups, i.e. M20 years [mean 21 (SD 1); n = 12], M40 [mean 40 (SD 2); n = 10] and M70 [mean 71 (SD 5); n = 10] volunteered as subjects for examination of maximal and explosive force production of leg extensor muscles in both isometric and dynamic actions (squat jump, SJ and counter movement jump, CMJ, and standing long-jump, SLJ). The balance test was performed on a force platform in both isometric and dynamic actions. Maximal bilateral isometric force value in M70 was lower (P < 0.001) than in M40 and as much as 46% lower (P < 0.001) than that recorded in M20 (P < 0.001). The maximal rate of force development (RFD) on the force-time curve was in M70 lower (P < 0.001) than in M40 and as much as 64% lower than in M20. The heights in SJ and CMJ and the distance in SLJ in M70 were lower (P < 0.001) than in M40 and M20 (P < 0.001). In response to modifications of the visual surroundings the older subjects were 24%-47% (P < 0.05 and P < 0.001) slower in their response time in reaching the lit centre (TT) and remained 20%-34% (P < 0.001) less time inside the centre (TC) from the overall time of lighting than M40 and M20, respectively. In both older groups the individual values of isometric RFD correlated significantly (P < 0.05) with the individual balance values of TT and TC. The present results would suggest that the capacity for explosive force production declines drastically with increasing age, even more than maximal muscle strength. Aging may also lead to impaired balance with a decrease in event detection and speed of postural adjustments. The decreased ability to develop force rapidly in older people seems to be associated with a lower capacity for neuromuscular response in controlling postural sway.

Measures of Reliability in Sports Medicine and Science

Article

Aug 2000

Will G Hopkins

Reliability refers to the reproducibility of values of a test, assay or other measurement in repeated trials on the same individuals. Better reliability implies better precision of single measurements and better tracking of changes in measurements in research or practical settings. The main measures of reliability are within-subject random variation, systematic change in the mean, and retest correlation. A simple, adaptable form of within-subject variation is the typical (standard) error of measurement: the standard deviation of an individual's repeated measurements. For many measurements in sports medicine and science, the typical error is best expressed as a coefficient of variation (percentage of the mean). A biased, more limited form of within-subject variation is the limits of agreement: the 95% likely range of change of an individual's measurements between 2 trials. Systematic changes in the mean of a measure between consecutive trials represent such effects as learning, motivation or fatigue; these changes need to be eliminated from estimates of within-subject variation. Retest correlation is difficult to interpret, mainly because its value is sensitive to the heterogeneity of the sample of participants. Uses of reliability include decision-making when monitoring individuals, comparison of tests or equipment, estimation of sample size in experiments and estimation of the magnitude of individual differences in the response to a treatment. Reasonable precision for estimates of reliability requires approximately 50 study participants and at least 3 trials. Studies aimed at assessing variation in reliability between tests or equipment require complex designs and analyses that researchers seldom perform correctly. A wider understanding of reliability and adoption of the typical error as the standard measure of reliability would improve the assessment of tests and equipment in our disciplines.

Validity of Double- and Single-Leg Vertical Jumps as Tests of Leg Extensor Muscle Function

Article

Mar 2001

The purpose of this research was to determine if 5 weeks of resistance training for the shoulder and hip flexor muscles produces improvements in vertical jumping (VJ) performance. Twenty-eight men were assessed on tests of shoulder power, leg extensor muscle function, and VJ performance using jumps performed from a standing position, a 3-stride run-up, and double- and single-leg takeoffs. A shoulder and hip flexor training group (n = 14) improved significantly more than a nontraining control group (n = 12) in shoulder power and 2 VJ performance tests, but not in the tests of leg extensor muscle function. It was concluded that the arm swing and free-leg drive significantly influence VJ performance and, therefore, VJ tests are not valid for assessment of leg extensor muscle function.

Konditions-Tests: Theorie und Praxis Alles Sportarten

Jan 1981

And S Starischka

GROSSER, M., AND S. STARISCHKA. Konditions-Tests: Theorie und Praxis Alles Sportarten. Munich: BLV Sportwissenschaft, 1981.

Sprungkrafttestgerat fur sportpraxis

Jan 1972
1425-1427

M Hoster

HOSTER, M. Sprungkrafttestgerat fur sportpraxis. Lehre der Leichtathletik 23:1425-1427. 1972.

Measurement of force-velocity characteristics for sports men in field conditions

Jan 1985
96-101

J T Viitasalo

VIITASALO, J.T. Measurement of force-velocity characteristics for sports men in field conditions. In: Biomechanics IX-A. D.A. Winter, R.W. Norman, R.P. Well, K.C. Hayes, and A.E. Patla, eds. Champaign, IL: Human Kinetics, 1985. pp. 96-101.

The throwing events: Recent trends in technique and training

Jan 1988
7-17

P Tschiene

TSCHIENE, P. The throwing events: Recent trends in technique and training. New Stud. Athletics 1:7-17. 1988.

Reliability of jumping performance in active men and women under different stretch loading conditions

Jan 2000
36-70

R Artega
C Dorado
J Chavarren
A L Calbert

ARTEGA, R., C. DORADO, J. CHAVARREN, AND A.L. CALBERT. Reliability of jumping performance in active men and women under different stretch loading conditions. J. Sports Med. Phys. Fitness 40:36-34. 2000.

Reliability and Factorial Validity of Squat and Countermovement Jump Tests

Abstract

No full-text available

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Reliability and Factorial Validity of Squat and Countermovement Jump Tests