Jump Height Research Articles

Acute Effect of Caffeine-Based Multi-Ingredient Supplement on Reactive Agility and Jump Height in Recreational Handball Players.

Pre-exercise caffeine and guarana-based multi-ingredient supplement (MS) consumption may be more effective for physical performance improvement than caffeine and guarana alone due to the synergistic effect of biologically active ingredients in multi-ingredient supplements. This study aimed to examine the acute effect of MS on the reactive agility and jump performance in recreational handball male players. A randomized, double-blind, crossover study involved twenty-four male handball players (body mass 74.6 ± 8.8 kg; body height 179 ± 7 cm; age 23.8 ± 1.4 years). Participants were tested under three conditions: placebo, caffeine + guarana (CAF + GUA), or MS ingestion 45 min before exercise tests. Participants performed a reactive agility test (Y-shaped test) and countermovement jump (CMJ). None of the supplements improved countermovement jump height (p = 0.06). The time needed to complete the agility test was significantly (p = 0.02) shorter in the MS condition than in the placebo. The differences in agility between PL vs. CAF + GUA and MS vs. CAF + GUA conditions were not statistically significant (p = 0.88 and p = 0.07, respectively). The results of this study indicate that the caffeine-based multi-ingredient performance was effective in improvement in reactive agility but not in jump height in recreational handball male players. A similar effect was not observed with CAF + GUA ingestion alone.

Droplet jumping physics on biphilic surfaces with different nanostructures and surface orientations under various air pressure conditions

Suffering from the adhesion of condensing water droplets, surface condensation performance is severely degraded. On a biphilic surface, condensing droplets efficiently nucleate while spontaneously being effectively removed from the surface due to the coalescence-induced droplet jumping phenomenon, significantly improving the surface condensation performance. However, it remains a challenge to appropriately tune the biphilic surface structure to maximize the droplet jumping performance and improve the condensation. Here, we report an experimentally verified droplet jumping theory that can optimize the biphilic surface structure, maximizing the droplet jumping height on the biphilic surface. Effects of surface orientation and air pressure are also investigated. The heat flux on the optimized biphilic surface can be enhanced by ∼43% and ∼139% compared with that on the superhydrophobic surface and a normal copper plate under atmospheric conditions, respectively, while that of the water collection flux can be improved by ∼61% and ∼273%, respectively. • A droplet jumping theory on biphilic surfaces is developed and verified • Surface structure, orientation, and air pressure are studied theoretically • The biphilic surface is optimized to maximize the droplet jumping height • Condensation heat transfer of the optimized biphilic surface is enhanced notably To maximize the droplet jumping height on a biphilic surface, Zhu et al. develop a droplet jumping theory, considering the surface structure, orientation, and air pressure. The optimized biphilic surface significantly enhances the condensation heat transfer, which benefits various thermal applications.

Backward Double Integration is a Valid Method to Calculate Maximal and Sub-Maximal Jump Height

ABSTRACT The backward double integration method uses one force plate and could calculate jump height for countermovement jumping, squat jumping and drop jumping by analysing the landing phase instead of the push-off phase. This study compared the accuracy and variability of the forward double integration (FDI), backwards double integration (BDI) and Flight Time + Constant (FT+C) methods, against the marker-based rigid-body modelling method. It was hypothesised that the jump height calculated using the BDI method would be equivalent to the FDI method, while the FT+C method would have reduced accuracy and increased variability during sub-maximal jumping compared to maximal jumping. Twenty-four volunteers performed five maximal and five sub-maximal countermovement jumps, while force plate and motion capture data were collected. The BDI method calculated equivalent mean jump heights compared to the FDI method, with only slightly higher variability (2–3 mm), and therefore can be used in situations where FDI cannot be employed. The FT+C method was able to account for reduced heel-lift distance, despite employing an anthropometrically scaled heel-lift constant. However, across both sub-maximal and maximal jumping, it had increased variability (1.1 cm) compared to FDI and BDI and should not be used when alternate methods are available.

Attenuated Lower Limb Stretch-Shorten-Cycle Capacity in ACL Injured vs. Non-Injured Female Alpine Ski Racers: Not Just a Matter of Between-Limb Asymmetry.

A retrospective analysis of routine countermovement jump (CMJ) testing, a coupled eccentric-concentric (stretch-shorten-cycle: SSC) movement, was performed in female elite alpine skiers with anterior cruciate ligament (ACL) reconstruction (ACLR) and without ACLR. A total of 567 tests obtained from the daily training environment were analyzed in 41 elite female athletes (non-injured control: n = 30, ACLR: n = 17), including n = 6 athletes with pre-injury data, between 16 and 32 years of age from alpine ski racing (n = 32) and skier cross (n = 9). Bilateral CMJ testing was conducted on a dual force plate system, and the limb-specific vertical ground reaction force (Fz) was analyzed to obtain the net eccentric deceleration impulse (Ecc), lower limb stiffness (Stiff), maximal vertical jump height (JH), peak external mechanical power (PP) exerted on the body center of mass (BCM), modified-reactive-strength-index (RSImod), and the loss in BCM velocity during the final phase of the takeoff Δ(Vmax–Vtakeoff). Eccentric and concentric phase-specific between-limb asymmetry indexes (AIs) were also calculated. Additive mixed effects models (AMMs) were used to compare the age-dependent and post-injury time course change between groups. The mean values for non-injured controls >25 years of age were used as a comparative benchmark for recovery given the absence of pre-injury data. Net eccentric deceleration impulse increased and Δ(Vmax–Vtakeoff) decreased with age for the non-injured control group (p < 0.001) while between-limb AI (mean ± SD) fell between 1 ± 5% for the concentric phase and 3 ± 7% for the eccentric deceleration phase. Between-limb asymmetry became smaller in ACLR skiers with time-from-surgery to reach non-injured control values by 2 years, but SSC function, such as JH and PP, remained depressed up to 5 years post-surgery (p < 0.01), indicating impairments in SSC function. This highlights the importance of evaluating SSC performance capacity alongside vertical jump force-time asymmetries in female ACLR alpine skiers.

Effects of a Postural Exercise Program on Vertical Jump Height in Young Female Volleyball Players with Knee Valgus.

Background: Although a knee valgus position is related to the increase in injury risk in volleyball players, there is a lack of studies on the relationship between knee valgus and vertical jump (VJ) performance. Hence, the aim of this study was to investigate the effects of a postural exercise program on VJ height in young female volleyball players with knee valgus. Methods: This pilot study included 19 young female volleyball players divided into the following groups: the Valgus Experimental Group (VEG); the Valgus Control Group (VCG); and the Neutral Control Group (NCG). All three groups carried out the same volleyball training program. In addition, only the VEG underwent a 3-month postural exercise program of 30–45 min/session, twice/week. VJ performance was measured through the Sargent test before (T0), at 6 weeks (T1), and at 12 weeks (T2). Results: A significant effect from T0 to T1 (p = 0.0017) and from T0 to T2 (p = 0.0001) was found in the VEG. No significant differences were found over time in the VCG and in the NCG. Conclusion: An integrated postural exercise program might lead to a more balanced muscle efficiency inducing athletes to obtain a higher VJ performance.

Identifying and reporting position-specific countermovement jump outcome and phase characteristics within rugby league.

The countermovement jump (CMJ) has been suggested to be an important test of neuromuscular performance for rugby league (RL) players. Identifying force platform-derived CMJ variables that may be more applicable to RL positions (e.g., forwards and backs) has yet to be fully explored in the scientific literature. The aim of this study was to identify RL position-specific CMJ force-time variables. Specifically, we aimed to compare select force-time variables from the countermovement (i.e., the combination of unweighting and braking) and propulsion phases of the CMJ between the global forwards and backs positional groups. We also aimed to compare typical (i.e., jump height) and alternative (i.e., take-off momentum) outcome CMJ variables between positional groups. Finally, we sought to visually present each individual player's CMJ performance alongside the average data to facilitate the interpretation and reporting of the CMJ performances of RL athletes. Twenty-seven forwards and twenty-seven backs who competed in the senior men's English RL Championship, performed three CMJs on a force platform at the beginning of the pre-season training period. There were no significant differences in any countermovement or propulsion phase variable between positions with just small effect sizes noted (P ≥0.09, d ≤0.46). Jump height (and so take-off velocity) was significantly greater for backs with moderate effects displayed (P = 0.03, d = 0.60). Take-off momentum (take-off velocity × body mass) was largely and significantly greater for forwards (P<0.01, d = 1.01). There was considerable overlap of individual player's body mass and CMJ outcome variables across positions, despite significant differences in the mean values attained by each positional group. The results suggest that it may be beneficial for RL practitioners to identify player-specific, or at least position-specific, variables. As a minimum, it may be worthwhile selecting CMJ force-time variables based on what is considered important to individual player's or small clusters of similar players' projected successes during RL competition.

Effects of plyometric and whole-body vibration on physical performance in collegiate basketball players: a crossover randomized trial

While many studies suggested the isolated effects of plyometric and whole-body vibration exercises on physical performance variables, only few studies have compared the acute effects of plyometric and whole-body vibration on the occurrence of post-activation potentiation and the resultant improvements in performance. Therefore, we aimed to compare the acute effects of plyometric exercises and whole-body vibration training on physical performance in collegiate basketball players. Twenty-four collegiate male basketball players (age 20.8 ± 2.02 years, height 1.79 ± 0.7 m, and weight 71.2 ± 7.6 kg) participated in this randomized crossover study. Subjects were received both plyometric and whole-body vibration exercises after a 48-h washed-out period. Countermovement Jump height, sprint, and agility time were measured at baseline, 4- and 12-min post-plyometric, and whole-body vibration exercises. The result suggests a positive effect of both the plyometric and whole-body vibration exercises on countermovement jump and agility time (p = 0.001). While the countermovement jump height and agility were higher in the plyometric group (mean difference 1.60 cm and 0.16 s, respectively), the sprint performance was higher in the whole-body vibration group. However, these differences were statistically non-significant between the two groups (p > 0.05). This study suggests that both plyometric and whole-body vibration exercises may improve post-activation potentiation, which leads to better physical performance.Trial registration CTRI/2019/05/019059. Registered with the Clinical trials registry, India on 10/05/2019. http://ctri.nic.in/Clinicaltrials/advsearch.php.

Countermovement Jump Force-Time Curve Analysis between Strength-Matched Male and Female Soccer Players.

The purpose of this study was to compare countermovement jump force–time measures between strength-matched male and female soccer players. Males (n = 11) and females (n = 11) were strength-matched via isometric mid-thigh pull testing, whereby peak force values were normalised to body mass. Subjects performed three maximal-effort countermovement jumps (CMJs) on a force platform from which a range of kinetic and kinematic variables were calculated via forward dynamics. Thereafter, differences in gross measures were examined via independent t-tests, while differences in force–, power–, velocity–, and displacement–time curves throughout the entire CMJ were analysed using statistical parametric mapping (SPM). Jump height, reactive strength index modified, propulsion mean force, propulsion impulse, and propulsion mean velocity were all greater for males (d = 1.50 to 3.07). Relative force– and velocity–time curves were greater for males at 86–93% (latter half of the concentric phase) and 85–100% (latter half of the concentric phase) of normalized movement time, respectively. Time to take-off, braking phase time, braking mean velocity and impulse, propulsion phase time and centre of mass displacement were similar between males and females (d = −0.23 to 0.97). This research demonstrates the strength of SPM to identify changes between entire force-time curves. Continued development and the use of SPM analysis could present the opportunity for a refined comparison of strength-matched male and female CMJ performance with the analysis of entire force–time curves.

Effects of Different Levels of Fatigue on Vertical Jump Performance, Vertical Stiffness, and Intralimb Coordination

This study aimed to investigate the acute effects of different levels of muscular fatigue on vertical jump perfor- mance, vertical stiffness, and intralimb coordination. Seventeen physically active men performed two fatigue protocols (low volume and high volume) composed of continuous vertical jumps on separate weeks. Jump height, vertical stiffness, and intralimb coordination were measured during countermovement vertical jumps prior to and immediately following the fatigue protocols. The jumps were performed on a force plate and filmed with high-speed cameras. The continuous relative phase was calculated as a measure of intralimb coordination. Mixed-model ANOVA was used to compare the variables between conditions and times. The fatigue index was greater in the high-volume protocol (27±12%) than in the low-volume protocol (16±7%). Jump height decreased (p≤0.01) after the high-volume protocol. Vertical stiffness decreased (p=0.05), and the continuous relative phase of thigh-shank coupling in the ascent phase of countermovement jumps increased (p=0.04) after both proto- cols. In conclusion, jump performance was only affected by higher fatigue indexes, while vertical stiffness and intralimb coordination were affected similarly irrespective of the fatigue levels.

Applying augmented feedback in basketball training facilitates improvements in jumping performance

ABSTRACT Augmented feedback, which is feedback about movement characteristics provided by an external source, can facilitate performance improvements. Results from recent studies, in which information about the jumping height were presented, indicated increased jumping performance due to augmented feedback. In the present study we aimed to utilize augmented feedback about the jumping height in regular basketball training. Therefore, augmented feedback was implemented and part of the training regime, and information about the jumping height was displayed while subjects performed catch and shoot exercises with the basketball. 18 subjects (9 with augmented feedback, 9 without augmented feedback) practiced for 3 weeks (9 training sessions). The subjects receiving augmented feedback, but not subjects in the control group, displayed increased jumping heights of countermovement-jumps and drop-jumps after the training. The ground contact times of countermovement-jumps and drop-jumps were not significantly changed after training. The number of successful hits, indicating ball performance, did also not change after training. Thus augmented feedback had no detrimental effect on sport-specific performance. The unchanged ground contact times of drop-jumps in combination with increased jumping heights indicate increased efficiency of stretch shortening cycle contractions. According to the positive effect of augmented feedback on jumping performance and the simplicity with which it was integrated into the training regime we recommend this method for regular basketball training. Highlights Augmented feedback about the jumping height in basketball training facilitated jumping height of countermovement-jumps and drop-jumps. The ground contact times were not altered, suggesting increased efficiency of the stretch-shortening cycle during jumping. According to the positive effect and its simple implementation augmented feedback is recommended for regular basketball training.

Active Video Games Improve Muscular Fitness and Motor Skills in Children with Overweight or Obesity.

(1) Background: Childhood obesity is an important public health problem. Children with overweight or obesity often tend to show the pediatric inactivity triad components; these involve exercise deficit disorder, pediatric dynapenia, and physical illiteracy. The aim of the study was to examine the influence of an active video games (AVG) intervention combined with multicomponent exercise on muscular fitness, physical activity (PA), and motor skills in children with overweight or obesity. (2) Methods: A total of 29 (13 girls) children (10.07 ± 0.84 years) with overweight or obesity were randomly allocated in the intervention group (AVG group; n = 21) or in the control group (CG; n = 8). The intervention group performed a 5-month AVG training using the Xbox 360® with the Kinect, the Nintendo Wii®, dance mats, and the BKOOL® interactive cycling simulator, combined with multicomponent exercise, performing three sessions per week. The control group continued their daily activities without modification. Weight, PA using accelerometers, and motor competence using the Test of Gross Motor Development 3rd edition were measured. Muscular fitness was evaluated through the Counter Movement Jump height, maximal isometric strength of knee extension and handgrip strength, and lean mass using Dual-energy X-ray Absorptiometry. Mann–Whitney U and Wilcoxon signed rank tests were performed. The biserial correlation coefficients (r) were calculated. Spearman’s correlation coefficients among PA, muscular fitness, and motor competence variables were also calculated. (3) Results: The AVG group significantly increased their knee extension maximal isometric strength (4.22 kg; p < 0.01), handgrip strength (1.93 kg; p < 0.01), and jump height (1.60 cm; p < 0.01), while the control group only increased the knee extension maximal isometric strength (3.15 kg; p < 0.01). The AVG group improved motor competence and light physical activity (p < 0.05) and decreased sedentary time (p < 0.05). Lean mass improved in both AVG group and CG (p < 0.05). Lastly, the percentage of improvement of motor skills positively correlated with the percentage of improvement in vigorous PA (r = 0.673; p = 0.003) and the percentage of improvement in CMJ (r = 0.466; p = 0.039). (4) Conclusions: A 5-month intervention combining AVG with multicomponent training seems to have positive effects on muscle fitness, motor competence, and PA in children with overweight or obesity.

Jumping Motion Based on Momentum Optimization Control and Differential Dynamic Programming for a Multilocomotion Robot

AbstractJumping motion is an indispensable motion mode for a multilocomotion robot, which will improve the crossing ability of the robot. This paper proposes a novel jumping control scheme for an MLR to perform jumping motion. The control strategy divides the whole jumping motion into three phases: the launch phase, the flight phase, and the landing phase. In the launch and landing phases, the controller is designed based on the centroid dynamics. By controlling the centroid momentum, the robot can achieve the desired centroid trajectory to obtain the initial take‐off speed in the launch phase and to maintain stability and reduce impact in the landing phase. In the flight phase, Differential Dynamic Programming algorithm is used to adjust the posture of the robot to further improve the jumping height and prepare for a smooth landing. Finally, the effectiveness of the proposed method is evaluated through simulations.

The Influence of Repeated Drop Jump Training on Countermovement Jump Performance.

Countermovement jump (CMJ) is used to assess athletic performance of the lower limbs. Drop jump (DJ) is an effect training method that can improve athlete's jumping performance. The main purpose of this study is to explore the effects of different drop jump heights (DJH)30, DJH40, and DJH50 cm for 250 drop jumps (DJs250) on CMJ. Eighteen male athletes were selected as subjects. After the 50th, 100th, 150th, 200th, and 250th DJs, perform 5 groups of CMJ (the average of 3 times for each group) and record them as the 50th, 100th, 150th, 200th, and 250th CMJ jumps (CMJs50, CMJs100, CMJs150, CMJs200, and CMJs250). The BTS motion capture system and two force plates are used to record data. The MATLAB software was used to analyze data through one-way ANOVA repeated measures. If there is a significant difference, the LSD method is used for post hoc comparison. Jump height (JH), contact time (CT), reaction intensity index (RSI), average rate of force development (ARFD), left average rate of force development (LARFD), and right average rate of force development (RARFD) of CMJs50, CMJs100, CMJs150, and CMJs200 at DJH50 were greater than those at DJH40 and DJH30 (all p < 0.05). DJH50 height and DJs200 training times can improve SSC mechanism and improve athlete CMJ performance.

A Wearable System for Jump Detection in Inline Figure Skating.

This article presents the design and experimental evaluation of a non-invasive wearable sensor system that can be used to acquire crucial information about athletes’ performance during inline figure skating training. By combining distance and time-of-flight sensors and gyroscopes, the system is able to detect when jumps are performed and provides a live view of the data (e.g., the number and height of jumps) through a graphical user interface. The main novelty of our approach lies in the way in which the optical sensors are orientated. Typically, the sensors are orientated horizontally and positioned in pairs on the ground, where they measure the time interval between the moment the athlete leaves the ground and the moment they land. In our system, an optical sensor is placed under each foot and is vertically orientated so as to constantly measure the distance from the ground. In addition, a gyroscope sensor is placed on the athlete’s back, which provides information on the direction and angular momentum of the movement. By combining this data, the system provides the accurate detection of various jumps and technical elements without any constraints on the training ground. In this paper, the system is also compared to similar platforms in the literature, although there are no other specific systems that are available for inline figure skating. The results of the experimental evaluation, which was performed by high profile athletes, confirm its effectiveness in correctly detecting jumps, especially considering its compromise between precision and the overall cost of the equipment.

Drop Jumping on Sand Is Characterized by Lower Power, Higher Rate of Force Development and Larger Knee Joint Range of Motion.

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

Reliability, Validity, and Performance Characteristics of Elite Adolescent Athletes at Different Stages of Maturity in the 10 to 5 Repeated Jump Test.

To examine the reliability, validity, and performance characteristics of the 10 to 5 repeated jump test (10-5 RJT) in adolescent male athletes. The 10-5 RJT has been shown to be a valid and reliable test of reactive strength index (RSI) in older adolescents (age 17-19y), but less is known in younger adolescent athletes at different stages of maturity. Athletes (age 11-17y) completed the 10-5 RJT on 2 days, 1 week apart, to examine the reliability (n = 41), validity (n = 18) of the test. Athletes were classified as pre, circa, or post peak height velocity (PHV) height velocity using maturity offset to examine the effect of maturation status on RSI, flight time (FT), ground contact time (GCT), and jump height (JH) (n = 68) using a cross-sectional design. Paired samples t tests showed no significant differences (P ≥ .05), and Bland-Altman analysis showed no bias and close limits of agreement for RSI, JH, FT, and GCT between the contact mat and force plate. Interday reliability was rated excellent for RSI (intraclass correlation coefficient = .91) and good for GCT, FT, and JH (intraclass correlation coefficient = .81-.85). All variables had a coefficient of variation ≤ 10%. RSI increased across maturation groups, with significant differences between pre-PHV and post-PHV groups (P = .014, d = 1.00). The 10-5 RJT is a valid and reliable test for adolescent male athletes. Greater RSI with advancing maturity was primarily due to increased FT and JH, with GCT remaining similar.

Optimizing Vertical Jumping Height of Single-Legged Robots with Passive TOE Joints Using the Genetic Algorithm

Legged robots have been interesting for researchers because they can move on uneven terrain and operate in dangerous areas for humans. Among these robots, the single-legged robot is an excellent choice to study because they are simpler than another legged robot. In this paper, we have designed a single-legged robot similar to the anatomy of the human leg. It consists of four active joints and one passive joint. The hip, knee, and ankle joint are considered active joints, and the toe joint is a passive joint. To make the simulation more accurate, we should define the physical property of the environment in detail. So, ground contact and friction model should be specified. After defining the robot model, we designed joint motion. Path planning aims to make the robot jump in the vertical direction. Besides, the robot must start jumping on the toe joint. The toe joint stiffness and damping play the leading role in jumping height. So, there should be optimum values for these parameters. The genetic algorithm is then used to optimize jumping height.

Effects of Verbal Encouragements on Selected Measures of Physical Fitness and Subjective Effort Perception in Young High School Students

: This study aimed to examine the effects of verbal encouragements (VE) on linear sprint speed, jump height, change of direction (CoD) speed, and subjective perception of effort among high school students. Twenty-three high school male students volunteered to participate in this study (age = 19.70 ± 1.06 years). Participants were evaluated during two separate sessions (first session with VE and second session without VE) in a randomized order. The teacher provided VE during each physical test. Jump height [squat jump (SJ), countermovement jump (CMJ), five jump test (FJT)], linear sprint speed (10-m and 30-m sprint), and CoD speed (30-m with CoD) were performed during the two sessions. The rating of perceived exertion (RPE) was recorded after each session. Results indicated that VE induced moderate but sig-nificant improvement in 10-m (ES = 0.71, P = 0.023) and 30-m (ES = 0.76, P = 0.016) sprint speed. However, the 30-m sprint with CoD did not change across conditions (P &gt; 0.05). For jump tests, significant moderate-to-large increases were observed under the VE compared with the non-VE condition (ES = 0.65 to 0.90; P = 0.005 to 0.037). Findings showed a large increase in effort perception following VE compared to the non-VE condition (ES = 1.54, P &lt; 0.001). In conclusion, the findings of this study indicated that VE has a positive impact on measures of physical fitness but increases effort perception.

The effect of muscular strength and strength asymmetry on jumping height in soccer players

BACKGROUND: Lower limb muscular asymmetry is not well studied and may have a negative impact on performance. OBJECTIVE: To estimate how muscular strength and strength asymmetry affect jumping performance in soccer players. METHODS: Twenty-eight male professional soccer players took part in the study. The countermovement jump (CMJ) without arm swing was used to determine jumping height. Muscle strength was measured concentrically at 60 and 300∘/s. RESULTS: The peak moment of the knee extensors was positively and significantly correlated with the CMJ; r= 0.608 at 300∘/s and r= 0.489 at 60∘/s. The asymmetry of the knee flexors between the stronger and weaker leg was negatively and moderately correlated with the CMJ at 300∘/s (r=-0.396). The regression model (R2= 0.474) showed that an increase of 0.18-Nm/kg in the relative strength of the knee extensors at 300∘/s (by one SD) was related to an increase of 3-cm in the CMJ. Reducing the asymmetry of the knee flexors by 6.8 percentage points (by one SD) was related to a rise of 1.7-cm in the CMJ. CONCLUSIONS: Greater strength in the knee extensors, preferably tested at higher velocity, and reduced asymmetry in the strength of the lower hamstring muscles have a statistically significant effect on the CMJ.

Short Post-warm-up Transition Times Are Required for Optimized Explosive Performance in Team Sports.

Abstract Silva, LM, Neiva, HP, Marques, MC, Izquierdo, M, and Marinho, DA. Short post-warm-up transition times are required for optimized explosive performance in team sports. J Strength Cond Res 36(4): 1134–1140, 2022—This study aimed to compare the effect of 3 different post-warm-up transition times (3, 10, and 17 minutes) on team sports performance. A randomized crossover research design was used. Fourteen university male basketball players completed the same 10-minute warm-up followed by a transition time of 3, 10, or 17 minutes until the performance assessment. In the control condition, no warm-up was performed. The performance was measured using the repeated sprint and jump ability test. Performance variables (time, jump height, and peak power) and physiological variables (lactate and tympanic temperature) were analyzed. Moderate effects were found between conditions for the best first 12.5-m sprint (F = 1.91, p = 0.17, = 0.13), with faster times after 3-minute transition (control: 2.51 ± 0.12 vs. 3 minutes: 2.41 ± 0.15, p = 0.02, effect size [ES] = 0.74). Jump heights were higher after transitions of 3 minutes (38.55 ± 5.07 cm, p &lt; 0.01, ES = 0.58), 10 minutes (37.69 ± 4.92 cm, p &lt; 0.01, ES = 0.40), and 17 minutes (37.87 ± 5.33 cm, p &lt; 0.01, ES = 0.42) compared with the control condition (35.84 ± 4.18 cm). However, no significant differences were found between resting conditions. The warm-up caused a moderate increase in lactate and temperature compared with no activity (F = 11.90, p &lt; 0.01, = 0.48; F = 2.56, p = 0.07, = 0.16, respectively), but changes from preperformance to postperformance evaluation showed no differences between experimental conditions. The results showed that the warm-up maximized the performance of explosive efforts. However, no significant differences were found between transition times. Despite a trend toward optimized explosive performances after a short post-warm-up transition time (3 minutes), further research is needed.