Countermovement Jump Height Research Articles

Effect of a High-Intensity Handball-Specific Fatigue Protocol Focused on the Leg Contralateral to the Throwing Arm on Interlimb Asymmetries.

Janicijevic, D, Pérez-Castilla, A, Miras-Moreno, S, Ortega-Becerra, M, Morenas-Aguilar, MD, Smajla, D, Sarabon, N, and García-Ramos, A. Effect of a high-intensity handball-specific fatigue protocol focused on the leg contralateral to the throwing arm on interlimb asymmetries. J Strength Cond Res 37(7): 1382-1389, 2023-This study aimed to elucidate which countermovement jump (CMJ) variant (unilateral or bilateral) is more sensitive to detect the decrement in kinetic CMJ-derived variables of the leg more actively involved in a handball-specific fatigue protocol. Seventeen female handball players (age: 20.6 ± 2.5 years) performed a fatigue protocol consisting of 8 repetitions of the following circuit separated by 10 seconds: 10 m sprint, 180° change of direction with the leg contralateral to the throwing arm, 10 m sprint with ball reception at 7 m, and handball throw preceded by a jump over a 40 cm hurdle with the leg contralateral to the throwing arm. Before and after the fatigue protocol, 6 unilateral CMJs (3 with each leg) and 3 bilateral CMJs were performed on a dual Kistler force platform (model 9260AA6). Bilateral CMJ height was reduced by 5.4% after the fatigue protocol (p < 0.001). However, the fatigue protocol did not promote any significant change in peak force, mean force, and propulsive impulse or in their asymmetry values (17 of 18 comparisons). The decrement of 6.1% during the unilateral CMJ in the propulsive impulse developed by the leg ipsilateral to the throwing arm (less involved in the fatigue protocol) was the only variable that reached statistical significance (p = 0.038). The pre-post fatigue changes in asymmetry values presented negligible correlations between both CMJ variants (rs = 0.01 to -0.19). These results suggest that neither unilateral nor bilateral CMJs are able to detect changes in interlimb asymmetries after a high-intensity handball-specific fatigue protocol.

Relationships Between Pre-Match Training Load Variables and Matchday Countermovement Jump Height in NCAA DI Women’s Soccer

Introduction: The purpose of this study was to assess the repeated measures correlations between the sums of training load (TL) variables preceding matchday and matchday countermovement jump (CMJ) height in NCAA Division I (DI) women’s soccer athletes. Methods: A total of 23 female soccer players (20 ± 1.2 years; 1.69 ± 0.06 m) participated in this study. Repeated measures correlations were used to determine the relationships between matchday CMJ height and TL variables. Results: Matchday CMJ height showed very weak to weak negative relationships with the sums of the TL variables for the microcycle preceding the match: sRPE-TL (r = -0.184, p = 0.036), TD (r = -0.229, p = 0.008), TLS (r = -0.192, p = 0.028), HSD (r = -0.229, p = 0.008), ML (r = -0.204, p = 0.020), and number of sprints (r = -0.237, p = 0.006). Conclusions: Although significant negative weak relationships were observed, the results suggest that the sums of TL variables preceding matchday may not be the most reliable indicators of matchday preparedness in collegiate DI women’s soccer. Future research should aim to investigate other strategies to predict matchday readiness in collegiate women’s soccer.

Acute Mechanical and Skin Temperature Responses to Different Interrepetition Rest Intervals During Full-Squat Exercise.

This study aimed to (1)evaluate the acute effects of different interrepetition rest full-squat protocols on countermovement jump (CMJ) height, velocity loss (VL), and skin temperature (Tsk) and (2)determine whether the VL, the changes in Tsk, or the individual strength level is associated with the change in CMJ height. Sixteen resistance-trained men randomly performed 3 squat protocols at maximal intended velocity with 60% of the 1-repetition maximum (sets × repetitions [interrepetition rest]): traditional (2 × 6 [0s]), cluster 2 (2 × 6 [30s every 2 repetitions]), and cluster 1 (1 × 12; [36s every repetition]), plus a control session. CMJ height was assessed before and 2, 4, and 8minutes after the protocols. There was a significant main effect of protocol for the VL (F = 20.54, P < .001) and loss in mean power (F = 12.85, P < .001; traditional > cluster 2 > cluster 1). However, we found a comparable reduction of CMJ height after 8minutes: traditional (-3.4% [4.2%]), cluster 2 (-5.3% [4.9%]), cluster 1 (-5.4% [2.9%]), and control (-4.2% [3.6%]). Overall, mean Tsk acutely decreased after all the protocols. Higher individual strength level (but not VL or the changes in Tsk) was associated with lower CMJ-height loss (P < .05). Although different interrepetition rest full-squat protocols may alter the loss in velocity and power, they result in a similar decrease in Tsk and CMJ height, which could be more influenced by individual strength level than VL or changes in Tsk.

The comparison between foam rolling either combined with static or dynamic stretching on knee extensors' function and structure.

Static stretching (SS) and dynamic stretching (DS) in combination with foam rolling (FR) have been attracting attention as warm-up routines in sports. However, the combined and intervention order effects of SS or DS and FR on flexibility, muscle strength, and jump performance are still unclear. Therefore, this study aimed to compare the combined effects of FR and SS or DS with the various intervention orders (i.e., SS + FR, DS + FR, FR + SS, DS + FR) on the function and properties of the knee extensors. Using a crossover, random allocation design, 17 male university students (21.0 ± 1.1 y) performed four conditions combining FR and SS or DS. The measurement included knee flexion range of motion (ROM), pain pressure threshold (PPT), tissue hardness, maximum voluntary isometric contraction (MVC-ISO), maximum voluntary concentric contraction (MVC-CON) torque, and single-leg countermovement jump (CMJ) height of the knee extensors. All interventions significantly (p < 0.01) increased knee flexion ROM (SS + FR: d = 1.29, DS + FR: d = 0.45, FR + SS: d = 0.95, FR + DS: d = 0.49), and significantly (p < 0.01) decreased tissue hardness (SS + FR: d = -1.11, DS + FR: d = -0.86, FR + SS: d = -1.29, DS + FR: d = -0.65). There were no significant changes in MVC-ISO, MVC-CON, and CMJ height in all conditions, but a near significant, small magnitude (p = 0.056, d = -0.31) decrease of MVC-ISO was observed in the FR + SS condition. Our results showed that all the combinations of SS or DS and FR effectively decreased tissue hardness and increased ROM without decreasing muscle strength. Also, effect sizes indicated the largest increase in ROM and decrease in tissue stiffness after SS + FR without decreasing muscle strength and jump performance.

Small-sided game-related physical performance is not influenced by the sprint and power performance of youth male soccer players

The aim of this study was to analyse the effects of sprint and power performance on physical fitness and small-sided game-related physical performance in youth male soccer players, using a median split analysis to separate faster and slower players, and powerful and weaker ones. Thirty youth male soccer players (age = 16.9 ± 1.4 years; height = 174.1 ± 7.1 cm; body mass = 63.1 ± 7.9 kg; % body fat = 15.5 ± 3.2) completed the following physical tests: 40 m linear sprint test, repeated sprint ability (RSA) test, countermovement jump (CMJ), horizontal jump (HJ) and a half-squat (HS) power test. In addition, players completed a 4 vs. 4 with goalkeepers small-sided game while external loads were recorded. According to their sprint and HS power performance, players were divided into fast and slow, and powerful and weak. Faster players performed better in 5 m sprint (p = 0.004, Effect Size (ES) = −1.158), 10 m sprint (p &lt; 0.001, ES =−1.722), 40 m sprint (p &lt; 0.001, ES = −3.268), RSAbest (p &lt; 0.001, ES = −2.415), RSAtotal (p &lt; 0.001, ES = −2.785), CMJ height (p = 0.032, ES = 0.823) and HJ distance (p &lt; 0.001, ES = 1.589), but no significant differences (p &gt; 0.05) were found in external loads during small-side games (SSG). In addition, no significant differences (p &gt; 0.05) were observed between powerful and weaker players in the fitness tests and SSG-related physical performance. These results highlight the importance of grouping youth soccer players by their sprinting capacity to design specific and individualized training strategies and suggest that SSG-related physical performance is not influenced by their sprint or power performance.

Relationship between unilateral and bilateral countermovement jump performance and force-velocity-power outcome variables

The main objective of the present study was to check the relationship between commonly used unilateral and bilateral countermovement jump (CMJ) performance variables (jump heights, unilateral CMJ jump/bilateral CMJ jump height index, reactive strength index modified and bilateral deficit) and Force-velocity-Power (F-v-P) outcomes from loaded CMJs. Seventeen physical education students performed unilateral CMJ jumps, bilateral CMJ jumps and two-load (20 and 70% of the participant’s body mass) F-v-P tests. The results show that bilateral CMJ jump, unilateral CMJ jump height and the reactive strength index modified calculated from the bilateral CMJ jump are moderately correlated (r = 0.567-0.633, p&amp;lt;.05) to F0. No statistically significant correlations were found between F-v-P outcomes and unilateral CMJ jump height to bilateral CMJ jump index, reactive strength index modified calculated from the unilateral CMJ jump and bilateral deficit. Multiple linear stepwise regressions between F-v-P outcomes and performance variables revealed that only F0 can be statistically significantly predicted by CMJ height (R2 = 40 %). Although the unilateral and bilateral CMJ tests are less time-consuming and less fatiguing than the progressive loaded CMJ jump test, the results of our study show that the mechanical properties of the lower extremities obtained by unilateral CMJ jump and bilateral CMJ jump cannot be generalized to those measured by F-v-P profiling.

Predictors of linear sprint performance in professional football players.

The purpose of this study was to analyze the relationship between sprint performance (time), and strength and power capabilities in football players. A total of 33 professional Portuguese football players performed isokinetic strength assessments, countermovement jumps (CMJ), squat jumps (SJ), and 10, 20 and 30 m sprints. Pearson's correlation (r) was used to determine the relationships between variables. Concentric knee extensor torque at 180° · s-1 was largely-to-very largely correlated with 10 m (r = -0.726), 20 m (-0.657) and 30 m sprints (r = -0.823). Moderate inverse correlation were observed between CMJ (r = -0.425 and r = -0.405) and SJ height (r = -0.417 and r = -0.430), and 20 m and 30 m sprint performance, respectively. Multiple linear regression combining KEcon 180° · s-1 and KFcon 180° · s-1 demonstrated that the model was significant for predicting 10 m sprint time (F (2, 8) = 5.886; R 2 = 0.595). The model combining SJ, CMJ and KEcon 180° · s-1 was also significant for predicting 20 and 30 m sprint times (F (3, 7) = 2.475; R 2 = 0.515 and F (3, 7) = 5.282; R 2 = 0.562; respectively). In conclusion, peak torque at higher velocities and vertical jump performance correlates significantly with linear sprint performance (time). For practitioners seeking to improve linear sprint performance in football players, evaluation of high speed strength and vertical jump indices should be undertaken.

Effects of Eurycoma longifolia Jack supplementation on eccentric leg press exercise-induced muscle damage in rugby players.

Eurycoma longifolia Jack (ELJ) is a herbal plant that has androgenic and antioxidant effects. We investigated the short-term effect of ELJ supplementation on muscle damage induced by eccentric exercise. Eighteen young (19-25 years), well-trained rugby 7s players were assigned to an ELJ or a placebo (PLA) group (n = 9/group). Each participant took four 100-mg capsules a day for seven days prior to performing a leg press eccentric exercise to failure in a double-blind fashion. Peak force, peak power and jump height in countermovement jump (CMJ), drop jump reactive strength index (RSI), muscle soreness assessed by a 100-mm visual analogue scale, plasma creatine kinase (CK) activity, and salivary hormones were measured at 24 h before and 0.5, 24, 48, 72, and 96 h after the exercise. Changes in the variables over time were compared between the groups by two-factor mixed-design ANOVA. The number of eccentric contractions performed was similar (P = 0.984) between the ELJ (21 ± 5) and PLA groups (21 ± 5). Salivary testosterone and cortisol concentrations did not change (P > 0.05) after the supplementation for both groups. CMJ peak power (-9.4 ± 5.6%) and height (-10.6 ± 4.9%), and RSI (-15.2 ± 16.2%) decreased at 24 h after exercise (P < 0.05), and muscle soreness (peak: 89 ±10 mm) and plasma CK activity (peak: 739 ± 420 IU/L) increased after exercise (P < 0.05) without significant differences between groups. These results showed that 7-day ELJ supplementation prior to the leg press eccentric exercise had no significant effects on hormones, performance and muscle damage markers for the athletes.

Accuracy of flight time and countermovement-jump height estimated from videos at different frame rates with MyJump.

Recent improvements in smartphone video technology may provide sufficient accuracy for estimation of jump height via flight time determined from video recordings of vertical-jump tests. The aim of this study is to evaluate the accuracy of jump height estimated from videos at different frame rates. High-definition videos of 10 young adults (6 males, 4 females) performing 5 countermovement jumps were recorded at a frame rate of 1000 Hz and transcoded to frame rates of 120, 240, and 480 Hz. Flight time in the videos was assessed independently by three observers at each of the four frame rates with MyJump. Flight time and jump height were analyzed with mixed models for estimation of means and of standard deviations representing technical error of measurement (free of within-subject jump-to-jump variability) at each frame rate. The four frame rates and three observers produced practically identical estimates of mean jump height. The technical errors at 120, 240, 480 and 1000 Hz were respectively 3.4, 1.8, 1.2 and 0.8 ms for flight time, and 1.4%, 0.7%, 0.5% and 0.3% for jump height. Assessed relative to either differences in jump height between elite football players (standard deviation of ~12%) or the smallest expected test-retest variability (typical error of ~3%), the technical error was substantial at 120 Hz but negligible at 240 Hz or higher. In conclusion, use of frame rates above 240 Hz to estimate jump height with MyJump will not improve accuracy substantially.

Profiling The Physiological Parameters of Boxers in The Parachute Regiment. ‘Every Man an Emperor’

This study aimed to collect and identify the physiological parameters that are required to produce winning performances in an army boxing competition. Army boxing competitions are sanctioned and governed by ‘England Boxing’ and consist of three rounds of two minutes with one-minute restorative periods. The Parachute Regiment are an elite infantry fighting force within the British military, with a continued success in the inter-army boxing championships. 22 male participants were recruited (mean ± SD age 28 ± 2 years, stature 178 ± 8.1cm, body mass 79 ± 7.1 kg, BMI 24.9 ±2.5).Body fat %. V̇O2max, lower limb power, and 1RM max strength test protocols for back squat and bench press were performed. Additionally, impact punch power measured from rear hand cross strikes, and punching velocities were measured using a linear positional transducer. Countermovement (CMJ) and repetitive (n=10) jump data were collected using a jump mat. The physiological parameters in mean scores; body composition showed body fat 11.8±8.1%: CMJ height 35.5±5cm: Repetitive jump 28.5±5.6cm: Wingate peak power (body mass to power ratio) 11.5±1.6W/kg: Wingate average power, 8.1±1.4W/kg: V̇O2max 53±4.8 ml.kg-1.min-1: Back squat (body mass to weight lifted ratio) 1.95±0.2kg: Bench press 1.1±0.1kg/BW: Rear cross strike velocity 8.47±0.8m/s: Impact power 15227±2250W. Significant relationships were observed between anthropometric data and power, strike velocity and V̇O2max in addition to relationships being evident between some strength and power variables. by the participants in this study. Although punch impact power is an essential performance indicator in boxing, other physiological factors, such as lower limb power and strength have been demonstrated to attribute to the continued winning performances by 3PARA boxing team.

Evidence-Based High-Loading Tendon Exercise for 12 Weeks Leads to Increased Tendon Stiffness and Cross-Sectional Area in Achilles Tendinopathy: A Controlled Clinical Trial

BackgroundAssuming that the mechanisms inducing adaptation in healthy tendons yield similar responses in tendinopathic tendons, we hypothesized that a high-loading exercise protocol that increases tendon stiffness and cross-sectional area in male healthy Achilles tendons may also induce comparable beneficial adaptations in male tendinopathic Achilles tendons in addition to improving pain and function.ObjectivesWe investigated the effectiveness of high-loading exercise in Achilles tendinopathy in terms of inducing mechanical (tendon stiffness, maximum strain), material (Young’s modulus), morphological (tendon cross-sectional area (CSA)), maximum voluntary isometric plantar flexor strength (MVC) as well as clinical adaptations (Victorian Institute of Sports Assessment—Achilles (VISA-A) score and pain (numerical rating scale (NRS))) as the primary outcomes. As secondary outcomes, drop (DJ) and counter-movement jump (CMJ) height and intratendinous vascularity were assessed.MethodsWe conducted a controlled clinical trial with a 3-month intervention phase. Eligibility criteria were assessed by researchers and medical doctors. Inclusion criteria were male sex, aged between 20 and 55 years, chronic Achilles tendinopathy confirmed by a medical doctor via ultrasound-assisted assessment, and a severity level of less than 80 points on the VISA-A score. Thirty-nine patients were assigned by sequential allocation to one of three parallel arms: a high-loading intervention (training at ~ 90% of the MVC) (n = 15), eccentric exercise (according to the Alfredson protocol) as the standard therapy (n = 15) and passive therapy (n = 14). Parameters were assessed pre- and-post-intervention. Data analysis was blinded.ResultsPrimary outcomes: Plantar flexor MVC, tendon stiffness, mean CSA and maximum tendon strain improved only in the high-loading intervention group by 7.2 ± 9.9% (p = 0.045), 20.1 ± 20.5% (p = 0.049), 8.98 ± 5.8% (p < 0.001) and −12.4 ± 10.3% (p = 0.001), respectively. Stiffness decreased in the passive therapy group (−7.7 ± 21.2%; p = 0.042). There was no change in Young’s modulus in either group (p > 0.05). The VISA-A score increased in all groups on average by 19.8 ± 15.3 points (p < 0.001), while pain (NRS) dropped by −0.55 ± 0.9 points (p < 0.001). Secondary outcomes: CMJ height decreased for all groups (−0.63 ± 4.07 cm; p = 0.005). There was no change in DJ height and vascularity (p > 0.05) in either group.ConclusionDespite an overall clinical improvement, it was exclusively the high-loading intervention that induced significant mechanical and morphological adaptations of the plantar flexor muscle–tendon unit. This might contribute to protecting the tendon from strain-induced injury. Thus, we recommend the high-loading intervention as an effective (alternative) therapeutic protocol in Achilles tendinopathy rehabilitation management in males.Clinical Trials Registration Number: NCT02732782.

Physical characteristics of handball elite male players

Abstract Introduction: The current handball performance, both nationally and internationally, has obvious progress in terms of the dynamics of the game in all phases of its development in attack and defense, characterized by the speed and complexity of development throughout the game. Anthropometric parameters and physical tests have been identified as fundamental to determining the success of handball performance. Examining fitness profiles could be of great importance for the optimal preparation of training plans and the orthopedic care of high-performance handball players. Materials and methods: Seven athletes from the handball club SCM Politehnica Timișoara, aged between 21 and 35, participated in this study. The tests conducted were aimed at evaluating the following parameters: body composition, strength of the lower and upper limbs and speed endurance. Results: The results obtained in body composition show an average value for weight of 90.14 ± 8.35kg, for BF 15.55 ± 2.79% and for BMI 25.32 ± 0.98 kg/m2. In dynamometric tests, the mean values were obtained for VJ height of 27.85 ± 6.02 cm, for CMJ height the value of 28.07 ± 2.74 cm and for SJ height the value of 27.42 ± 2.67 cm. The mean value for the maximum oxygen consumption VO2max was 49.32 ± 2.32 ml / kg / min, and for the total distance traveled was obtained, 1714.28 ± 208.7 m. Conclusions: Analyzing the data obtained and by comparison with international average reference values, it can be concluded that a specific physical training regime based on the level and position of the player on the field is needed to improve the technical procedures during the match and prevent injuries.

Preseason Integrative Neuromuscular Training Improves Selected Measures of Physical Fitness in Highly Trained, Youth, Male Soccer Players.

Hammami, R, Negra, Y, Nebigh, A, Ramirez-Campillo, R, Moran, J, and Chaabene, H. Preseason integrative neuromuscular training improves selected measures of physical fitness in highly trained, youth, male soccer players. J Strength Cond Res 37(6): e384-e390, 2023-This study examined the effects of an 8-week integrative neuromuscular training (INT) program, including balance, strength, plyometric, and change of direction exercises, on measures of physical fitness in youth male soccer players. Twenty-four male soccer players participated in this study. They were randomly allocated into an INT (n = 12; age = 15.7 ± 0.6 years, body height = 179.75 ± 6.54 cm, body mass = 78.20 ± 7.44 kg, maturity-offset = +2.2 ± 0.6 years) or an active control (CG, n = 12; age = 15.4 ± 0.8 years, body height = 178.4 ± 6.4 cm, body mass = 72 ± 8.3 kg, maturity-offset = +1.9 ± 0.7 years) group. Before and after training, tests to measure dynamic balance (Y-Balance test [YBT]), muscle strength (one repetition maximum [1RM]), muscle power (five jump test [FJT], single-leg hop test [SLHT], and countermovement jump [CMJ] height), linear sprint time (10 and 30-m), and change of direction with ball (CoDball) were performed. The analysis of covariance was used to test between-group differences (INT vs. CG) at posttest using baseline values as covariates. Significant, large, between-group differences at posttest were noted for the YBT (p = 0.016; d = 1.1), 1RM (p = 0.011; d = 1.2), FJT (p = 0.027; d = 1.0), SLHT (p = 0.04; d = 1.4), CMJ height (p < 0.001; d = 1.9), 10-m sprint (p < 0.01; d = 1.6), and CoDball (p < 0.05; d = 0.9) in favor of the INT group. Significant moderate-to-large pre-to-post changes were detected in the INT group for YBT, 1RM, CMJ height, SLHT, FJT, 10-m and 30-m sprint time, and CoDball test (d = 0.7 to 3.07, p < 0.05). No significant pre-to-post changes were observed in the CG (p > 0.05), except for 10-m sprint time (d = 1.3; p < 0.05). Exposure to INT twice weekly is effective and time efficient to improve various measures of physical fitness in highly trained youth male soccer players.

Acute Effects of Heavy Strength Training on Mechanical, Hemodynamic, Metabolic, and Psychophysiological Parameters in Young Adult Males.

This study analyzed the acute effects of heavy strength training on mechanical, hemodynamic, metabolic, and psychophysiological responses in adult males. Thirteen recreational level males (23.3 ± 1.5 years) randomly performed two heavy strength training sessions (3 sets of 8 repetitions at 80% of one repetition maximum [1RM]) using the bench press (HST-BP) or full squat (HST-FS)). The repetition velocity was recorded in both sessions. Moreover, before and after the sessions, the velocity attained against the ~1.00 m·s−1 load (V1Load) in the HST-BP, countermovement jump (CMJ) height in the HST-FS, blood pressure, heart rate, blood lactate, and psychophysiological responses (OMNI Perceived Exertion Scale for Resistance Exercise) were measured. There were differences between exercises in the number of repetitions performed in the first and third sets (both <8 repetitions). The velocity loss was higher in the HST-BP than in the HST-FS (50.8 ± 10.0% vs. 30.7 ± 9.5%; p < 0.001). However, the mechanical fatigue (V1Load vs. CMJ height) and the psychophysiological response did not differ between sessions (p > 0.05). The HST-FS caused higher blood pressure and heart rate responses than the HST-BP (p < 0.001 and p = 0.02, respectively) and greater blood lactate changes from pre-training to post-set 1 (p < 0.05). These results showed that the number of maximal repetitions performed in both sessions was lower than the target number and decreased across sets. Moreover, the HST-BP caused a higher velocity loss than the HST-FS. Finally, the HST-FS elicited higher hemodynamic and metabolic demand than the HST-BP.

Acute Effects of High-Load vs. Plyometric Conditioning Activity on Jumping Performance and the Muscle-Tendon Mechanical Properties.

Krzysztofik, M, Wilk, M, Pisz, A, Kolinger, D, Bichowska, M, Zajac, A, and Stastny, P. Acute effects of high-load versus plyometric conditioning activity on jumping performance and the muscle-tendon mechanical properties. J Strength Cond Res 37(7): 1397-1403, 2023-The effectiveness of high-load and plyometric exercises as conditioning activity (CA) is not well described in the level of performance enhancement and muscle-tendon properties. Therefore, this study aimed to compare the effectiveness of high-loaded back squats and body mass tuck jumps among amateur soccer players on the height of countermovement jump performed without (CMJ) and with arm swing (CMJa) and to verify the usefulness of the myotonometry in assessing the level of CA-induced fatigue. Therefore, 16 male amateur soccer players (resistance training experience: 2 ± 1 year, relative 1 repetition maximum back squat strength: 1.41 ± 0.12 kg·body mass-1) performed 3 experimental sessions to compare the acute effects of 3 sets of 3 repetitions at 85% one repetition maximum of half back squats (HL), 3 sets of 5 repetitions of tuck jump exercises (PLY), and no CA (CTRL) on CMJ and CMJa height. Moreover, the gastrocnemius medialis and Achilles tendon tone and stiffness were examined. Measurements were performed 5 minutes before CA and in the third, sixth, and ninth minutes after CA. The CMJ height significantly increased from pre-CA to post-CA in the CTRL (p = 0.005; effect size [ES] = 0.36; Δ = +3.4%) and PLY (p = 0.001; ES = 0.83; Δ = +8.8%) conditions. Moreover, post-CA jump height was significantly higher in PLY than in the HL condition (p = 0.024; ES = 0.6; Δ = +5.9%). No significant differences were found for CMJa height, tone, and stiffness of gastrocnemius medialis and Achilles tendon. The low-volume plyometric CA (i.e., 3 sets of 5 repetitions) is recommended instead of high-loaded CA (≥85% one repetition maximum) for amateur athletes. In addition, it has been established that the performance improvement was independent of changes in the mechanical properties of the gastrocnemius medialis and Achilles tendon. Furthermore, it seems that the complexity of the post-CA task may affect the magnitude of the postactivation performance enhancement.

Evaluation of Neuromuscular Fatigue in a Repeat Sprint Ability, Countermovement Jump and Hamstring Test in Elite Female Soccer Players.

The straight-line run is the most frequent action in soccer goal scoring situations, and it deserves considerable attention. The objective of this study was to evaluate the neuromuscular fatigue produced by an independent repeat sprint ability (RSA) test, a countermovement jump (CMJ) and a hamstring test (HT) in elite female soccer players. Twenty-four elite female soccer players participated in the study. The evaluation protocol included hamstring and CMJ tests before an RSA test (6 × 40 m 30 s rest), and hamstring and CMJ post-tests. Significant differences were found between pre-post HT measurements in the maximum angulation of the right leg (p = 0.012 Effect Size (ES) = 0.27), and the maximum velocity was higher in the left leg after RSA (p = 0.023 ES = 0.34). CMJ height after RSA was significantly lower than before the RSA test (p < 0.001 ES = 0.40). The sprint total time (SprintTT) and percentage difference (%Dif) increased throughout the RSA (p < 0.001, and ES = 0.648 and ES = 0.515, respectively). In elite female soccer players, it seems that the fatigue induced by an RSA test can be assessed through the loss of CMJ height and the different performance variables extracted from the RSA itself (e.g., SprintTT, Ideal Sprint). These findings could contribute to better performance management and injury prevention for elite female soccer players.

Validity of the Baiobit Inertial Measurements Unit for the Assessment of Vertical Double- and Single-Leg Countermovement Jumps in Athletes.

Jump tests are simple, quick to execute, and considered the most reliable tool to measure lower extremities power and explosiveness in athletes. Wearable inertial sensors allow the assessment of jumping performance on any surface. The validity of inertial sensors measurements is a pivotal prerequisite to reliably implement their utilization in the clinical practice. Twenty-seven athletes (20 M/7 F, age: 27 ± 7 years old) performed five double-leg countermovement jumps (CMJs) and three single-leg CMJs per side with their hands on their hips. Jump height was measured/computed simultaneously with the optoelectronic system, force platforms, and the Baiobit inertial sensor system. The athletes completed the international physical activity questionnaire (IPAQ). When comparing the methods (Baiobit vs. force platforms), a non-statistically significant bias of 1.8 cm was found for two-leg CMJs and -0.6 cm for single-leg CMJs. The intraclass correlation coefficients (ICCs) was "excellent" for double-leg CMJs (ICC = 0.92, 95% CI = 0.89-0.94) and "good" for single-leg CMJs (ICC = 0.89, 95% CI = 0.85-0.91). When comparing the methods (Baiobit vs. force platforms + optoelectronic system), a non-statistically significant bias of -0.9 cm was found for two-leg CMJs and -1.2 cm for single-leg CMJs. The intraclass correlation coefficient (ICC) was "good" for both double-leg CMJs (ICC = 0.80, 95% CI = 0.73-0.85) and for single-leg CMJs (ICC = 0.86, 95% CI = 0.80-0.89). Baiobit tends to overestimate double- and single-leg CMJ height measurements; however, it can be recommended in the world of rehabilitation and sport analysis.

Monitoring Internal Training Intensity Correlated with Neuromuscular and Well-Being Status in Croatian Professional Soccer Players during Five Weeks of the Pre-Season Training Phase.

This study aimed to investigate the changes in internal training intensity, well-being, and countermovement jump (CMJ) performance and to determine their relationship across five weeks of the pre-season training phase in professional soccer players. A total of 22 professional male soccer players (age = 21.7 ± 4 years, body height = 185.9 ± 6.3 cm, body weight = 79 ± 6.3 kg, BMI = 22.8 ± 1.4 kg·m-2; VO2max = 52.9 ± 3.2) from the Croatian Second League voluntary participated in this study. The players spent 2230 ± 117 min in 32 technical/tactical and strength/conditioning training sessions, mostly at the low intensity zone (61%), and played 8 friendly matches at a high intensity (&gt;90%). A one-way repeated measure of analysis ANOVA revealed a significant difference between weeks in CMJ performance (F(1,22) = 11.8, p &lt; 0.001), with CMJ height in weeks 4 and 5 being likely to very likely higher than that noted in week 1. Moreover, significant differences between weeks were found in all internal training intensity measures (average [F(1,22) = 74.8, p &lt; 0.001] and accumulated weekly internal training intensity [F(1,22) = 55.4, p &lt; 0.001], training monotony [F(1,22) = 23.9, p &lt; 0.001], and training strain [F(1,22) = 34.5, p &lt; 0.001]). Likewise, differences were observed for wellness status categories (fatigue [F(1,22) = 4.3, p = 0.003], sleep [F(1,22) = 7.1, p &lt; 0.001], DOMS [F(1,22) = 5.7, p &lt; 0.001], stress [F(1,22) = 15.6, p &lt; 0.001]), mood [F(1,22) = 12.7, p &lt; 0.001], and overall well-being status score (F(1,22) = 13.2, p &lt; 0.001). Correlation analysis showed large negative correlations between average weekly internal training intensity and fatigue (r = -0.63, p = 0.002), DOMS (r = -0.61, p = 0.003), and WBI (r = -0.53, p = 0.011). Additionally, fatigue was significantly associated (large negative correlation) with accumulated weekly internal training intensity (r = -0.51, p = 0.014) and training strain (r = -0.61, p = 0.003). Small, but non-significant, correlations were found between CMJ performance and wellness status measures. These findings highlight the utility and simplicity of monitoring tools to improve athletes' performance.

Effects of flywheel resistance training using horizontal vs vertical exercises

Flywheel resistance training is a very useful method to optimize athletic performance. However, research assessing the different loading conditions hypothesis during flywheel resistance training is scarce. The aim of this study was to assess the influence of the loading conditions used during flywheel resistance exercise on improvements in athletic performance. Twenty nine (29) athletes were randomly assigned to three different flywheel resistance training groups: vertical-directed exercises (VR), horizontal-directed exercises (HR) and a mixed group (MIX). Performance assessment included one repetition maximum (1-RM) in the half-squat exercise, countermovement jump (CMJ) performance and change of direction (COD) ability (5-0-5 agility test). For the 1-RM squat, significant improvements were found in the VR ( p = 0.011) and MIX groups ( p = 0.015). All groups showed significant increases in CMJ height ( p &lt; 0.05), and significant decreases in 5-0-5 time with the non-dominant leg ( p &lt; 0.05). As regards 5-0-5 with the dominant leg, the VR ( p = 0.004) and MIX groups ( p = 0.001) showed significant decreases in 5-0-5 time. Non-significant group × time interactions were noted. In conclusion, all groups showed similar improvements in 1-RM squat, jumping and COD performance. However, the inclusion of vertical-directed exercises seems to optimize increases in 1-RM squat.

No effect of repeated post-resistance exercise cold or hot water immersion on in-season body composition and performance responses in academy rugby players: a randomised controlled cross-over design

PurposeFollowing resistance exercise, uncertainty exists as to whether the regular application of cold water immersion attenuates lean muscle mass increases in athletes. The effects of repeated post-resistance exercise cold versus hot water immersion on body composition and neuromuscular jump performance responses in athletes were investigated.MethodsMale, academy Super Rugby players (n = 18, 19.9 ± 1.5 y, 1.85 ± 0.06 m, 98.3 ± 10.7 kg) participated in a 12-week (4-week × 3-intervention, i.e., control [CON], cold [CWI] or hot [HWI] water immersion) resistance exercise programme, utilising a randomised cross-over pre–post-design. Body composition measures were collected using dual-energy X-ray absorptiometry prior to commencement and every fourth week thereafter. Neuromuscular squat (SJ) and counter-movement jump (CMJ) performance were measured weekly. Linear mixed-effects models were used to analyse main (treatment, time) and interaction effects.ResultsThere were no changes in lean (p = 0.960) nor fat mass (p = 0.801) between interventions. CON (p = 0.004) and CWI (p = 0.003) increased (g = 0.08–0.19) SJ height, compared to HWI. There were no changes in CMJ height (p = 0.482) between interventions.ConclusionRepeated post-resistance exercise whole-body CWI or HWI does not attenuate (nor promote) increases in lean muscle mass in athletes. Post-resistance exercise CON or CWI results in trivial increases in SJ height, compared to HWI. During an in-season competition phase, our data support the continued use of post-resistance exercise whole-body CWI by athletes as a recovery strategy which does not attenuate body composition increases in lean muscle mass, while promoting trivial increases in neuromuscular concentric-only squat jump performance.