Countermovement Jump Test Research Articles

Peak Lower-Extremity Power Unadjusted for Body Mass Predicts Fastball Velocity in Collegiate Baseball Pitchers.

King, BW, Snow, TK, and Millard-Stafford, M. Peak lower-extremity power unadjusted for body mass predicts fastball velocity in collegiate baseball pitchers. J Strength Cond Res XX(X): 000-000, 2024-The relationship between lower-extremity power production and fastball velocity in collegiate pitchers remains unclear. This study aimed to evaluate the relationship between lower-extremity power and throwing velocity in 33 National Collegiate Athletic Association Division I baseball pitchers. Lower-extremity power was quantified using countermovement jump (CMJ) testing on force plates and the Wingate anaerobic cycling test. In-game fastball velocities were collected using TrackMan technology. Pearson correlations and linear regressions were used to evaluate the association between lower-body power and fastball velocity. The strongest predictor of peak fastball velocity was body mass ( r = 0.58, p = 0.0004), followed by lean mass ( r = 0.52, p = 0.002). Peak power (W) produced on the Wingate and CMJ tests were each statistically significant predictors of peak velocity ( r = 0.44, p = 0.011; r = 0.43, p = 0.014, respectively), but CMJ power relative to body mass ( r = 0.19), jump height ( r = 0.07), and Sparta Scores ( r = -0.06) were not ( p > 0.05). Linear regression indicated Wingate and CMJ absolute peak power tests each independently explained 19% of the variance in fastball velocity but added little to the model when combined with body mass (∼34 vs. 32% of total variance). Because total body mass and lower-body power are important predictors of pitching velocity, absolute power output is a more relevant predictor of baseball pitching velocity than lower-body power variables influenced by body mass (e.g., jump height and Sparta Score).

Magnitude and Direction of Interlimb Asymmetry and the Association of Interlimb Asymmetry with Physical Performance in Judo Athletes with Visual Impairment.

For judo athletes with visual impairments and their coaches, understanding possible muscle adaptations can be challenging. As it is commonplace for these adaptations to include interlimb asymmetry, we analyzed the magnitude and direction of interlimb asymmetry in judo athletes with visual impairments and verified the association of this asymmetry with their unilateral physical performances. Participants were 18 elite judo athletes (10 male, 8 female) with visual impairments. These athletes performed three physical tests: countermovement jump (CMJ), medicine ball throw (MBT), and handgrip strength (HGS), while we conducted unilateral right and left side assessments using the interlimb asymmetry equation for each physical test. Our main results showed that the CMJ and MBT tests presented asymmetry values above 10%; with CMJ significantly higher than HGS (p = 0.050), and with inconsistencies across the three tests in the direction of interlimb asymmetry (k = -0.22-0.26). Unilateral CMJ (left limb) was negatively correlated with asymmetry (r = -0.51; p = 0.031), and unilateral MBT (right limb) was positively correlated with asymmetry (r = 0.52; p = 0.024). Based on these results, coaches should prioritize regular assessments of interlimb asymmetry using these specific tests. This data can guide the construction of training programs aimed at minimizing asymmetry and enhancing overall physical performance. Continuous monitoring and adjustment of training strategies based on asymmetry findings are crucial for optimizing muscle balance in judo athletes with visual impairments.

Intra- and inter-session reliability of countermovement jump and gait analysis in collegiate athletes measured using an inertial measurement unit (BTS G-Walk)

This study assessed the intra- and inter-session reliability of the inertial measurement unit (IMU) in measuring countermovement jump (CMJ) and 10m-walking gait-related outcomes. Thirty collegiate-level athletes (15 males [age: 21.0 ± 2.5 years] and 15 females [age: 21.5 ± 2.1 years]) were recruited to perform CMJs and 10m-walking test that were simultaneously recorded using the commercially available body-worn IMU – BTS G-walk. The coefficient of variation (CV), the analysis of variance with repeated measures (ANOVA), and the interclass correlation coefficient (ICC) were used for intra-session reliability. While the Pearson’s correlation coefficient (r) and the ICC were used to analyze inter-session reliability. Measurement of CMJ and 10m-walking test gait variables using the IMU resulted in moderate to excellent intra-session reliability for CMJ (ICC = 0.881 to 0.988) and gait analysis (ICC = 0.807 to 0.978) with acceptable CV (≤10%). Inter-session reliability for CMJ variables ranged from poor to excellent (ICC = 0.134 to 0.963), and 10-m walking test gait analysis variables were moderate to excellent (ICC = 0.683 to 0.931). The IMU (BTS G-walk) provides reliable data for most CMJ and gait variables. Future studies may determine the accuracy of the equipment to monitor changes over time (e.g., after a training intervention).

Caffeine, but not paracetamol (acetaminophen), enhances muscular endurance, strength, and power.

Caffeine is one of the most popular ergogenic aids consumed by athletes. Caffeine's ergogenic effect has been generally explained by its ability to bind to adenosine receptors, thus modulating pain and reducing perceived exertion. Another pharmacological agent that may improve performance due to its analgesic proprieties is paracetamol. This study aimed to explore the effects of caffeine, paracetamol, and caffeine + paracetamol consumption on muscular endurance, strength, power, anaerobic endurance, and jumping performance. In this randomized, crossover, double-blind study, 29 resistance-trained participants (11 men and 18 women) ingested either a placebo, caffeine (3 mg/kg), paracetamol (1500 mg) or caffeine + paracetamol 45 min before the testing sessions. The testing sessions included performing the bench press exercise with 75% of one-repetition maximum to momentary muscular failure, isokinetic knee extension and flexion at angular velocities of 60°/sec and 180°/sec, Wingate, and countermovement jump (CMJ) tests. Compared to placebo, isolated caffeine ingestion increased the number of repetitions performed in the bench press (p = 0.005; d = 0.42). Compared to placebo, isolated caffeine ingestion and/or caffeine + paracetamol consumption was ergogenic for strength (torque), muscular endurance (total work), or power in the isokinetic assessment, particularly at slower angular velocities (p = 0.027 to 0.002; d = 0.16 to 0.26). No significant differences between the conditions were observed for outcomes related to the Wingate and CMJ tests. This study provided novel evidence into the effectiveness of caffeine, paracetamol, and their combination on exercise performance. We found improvements in muscular endurance, strength, or power only when caffeine was consumed in isolation, or in combination with paracetamol. Isolated paracetamol consumption did not improve performance for any of the analyzed outcomes, thus calling into question its ergogenic potential.

The Influence of Ankle Mobility and Foot Stability on Jumping Ability and Landing Mechanics: A Cross-Sectional Study.

Practicing physical activities or sports that involve frequent jumping and landing can strain the muscles and joints of the lower limbs, especially in those who do not have adequate physical preparation. The objective of this study was to (a) determine the correlation between ankle range of motion (ROM) and landing stability following jumps; (b) assess the association between the jump height in a counter-movement jump (CMJ) test and ankle ROM; and (c) examine the connection between stabilometry during specific jumps movements present in many sports and in ankle stabilization. Sixty-two healthy amateur volleyball players participated in the study (age: thirty-seven females and twenty-five males; age (years): 16.5 ± 4.25; height (cm): 166 ± 11.4; weight (Kg): 61.6 ± 13.7). Participants were recruited for the study in collaboration with student sports associations. The evaluations encompassed the measurement of ankle joint mobility for both lower limbs using an inertial sensor, a static baropodometric and stabilometric analysis using a pressure platform, and the CMJ test using the Microgate system. After the assessments, participants performed a "specific jump landing task". Significant correlations were found between foot range of motion (ROM) and counter-movement jump (CMJ) performance. Specifically, the ROM of the right foot had a strong correlation with the CMJ (r = 0.81, p < 0.001), while the left foot ROM showed a moderate correlation (r = 0.46, p < 0.001). The specific jump task revealed substantial changes in stabilometry parameters, particularly during forward hops compared to lateral jumps. Dorsiflexion ROM significantly impacts jumping ability. Evaluating landing patterns and stabilometry during targeted activities can help optimize training, improve dynamic balance, and reduce ankle injury risk.

Post-activation performance enhancement of flywheel and traditional squats on vertical jump under individualized recovery time.

To explore the post-activation performance enhancement (PAPE) of flywheel and traditional squats on a series of vertical jumps, the loads of the two protocols were matched based on their linear velocities. In addition, we attempted to validate the effectiveness of determining individualized recovery time (IRT) between conditioning activities and explosive movements. Sixteen trained players participated in three main experiments: first, one-repetition maximum (1RM) assessment and intensity matching test; second, the weighted jump squat (WJS) test at baseline and at 2, 4, 6, 8, and 10min after flywheel and traditional protocols; and third, squat jump (SJ), countermovement jump (CMJ), and approach jump (AJ) tests incorporating IRT determined in the WJS sessions into both protocols. These protocols were standardized to 8 repetitions at 80% 1RM with equivalent concentric speed matched by a linear position transducer and conducted in a random order on separate days. In the WJS tests, both protocols exhibited significant increases on jump height (JH), peak force (PF), and peak power (PP) after 2 to 6min (all p < 0.05), and the time courses of changes in performance were in a similar trend. In the SJ, CMJ, and AJ tests, both protocols demonstrated highly significant increases on JH, PP, and reactive strength index (RSI) after incorporating IRT (all p < 0.01), with all participants exhibiting diverse improvement above the baseline levels. The potentiation percentages of the flywheel protocol on JH, PP, and RSI were higher than those of the traditional protocol across four jumping types (JH: 5.35%-9.79% vs. 4.13%-8.46%; PP: 4.16%-6.13% vs. 3.23%-4.77%; and RSI: 7.27% vs. 7.04%). High-intensity flywheel squats can produce jumping potentiation in neuromechanical factors comparable to, or even surpassing, those observed in traditional squats, potentially making them a more effective option for inducing PAPE. Additionally, incorporating IRT into potentiation protocols could further optimize the PAPE effects.

Correlation of anthropometric characteristics and movement behavior with lower extremity muscle power and dynamic knee valgus in adolescent basketball athletes.

The anthropometric characteristics of adolescent basketball athletes can determine their ability to produce muscle power. Lack of physical activity (PA) level or an increased sedentary life seem to be associated with the overall health status and the occurrence of knee injuries. The aim of this paper was to identify possible correlations between anthropometric characteristics, body composition, exposure time to electronic devices or screen time (ST), and PA level along with muscle power and dynamic knee valgus (DKV) in young basketball athletes. Anthropometric and demographic characteristics were recorded. PA level was assessed through the International Physical Activity Questionnaire, and ST was assessed through a single question from the HELENA study. The Counter Movement Jump test was used for the evaluation of the lower limb muscle power, while the Single Leg Drop Jump test was used for the evaluation of the DKV via two-dimensional (2D) kinematic analysis. One hundred twenty-five adolescent basketball athletes (66.4% boys), 12 to 17 years old (13.94±1.58 years) participated. The Pearson index showed a statistically significant positive correlation between muscle power and height (r=0.788, P<0.001), while the Spearman Index showed a more minor but equally statistically significant positive correlation with Body Mass Index (rs=0.651, P<0.001) and age (rs=0.579, P<0.001). The ST (rs= -0.194, P=0.03) showed a weak negative correlation with DKV, while PA (r=0.85, P<0.001) showed a high, statistically significant, positive correlation. A high level of PA could play a key role in compensating and thus reducing the negative effects of high exposure to ST on the DKV.

Countermovement Jump and Momentum Generation Associations to Fastball Velocity Performance Among Division I Collegiate Pitchers.

Sakurai, M, Qiao, M, Szymanski, DJ, and Crotin, RL. Countermovement jump and momentum generation associations to fastball velocity performance among Division I collegiate pitchers. J Strength Cond Res 38(7): 1288-1294, 2024-The current study explored the relationships between countermovement jump (CMJ) profiles and baseball pitching performance. Nineteen Division I collegiate pitchers performed in-laboratory pitching and bilateral CMJs. Whole-body kinematics and ground reaction force were collected during both pitching and CMJ evaluations. Statistically significant correlations of concentric impulse and peak power in the CMJ test with fastball velocity were observed (r = 0.71 and 0.68). Concentric impulse in CMJ also showed a statistically significant correlation with linear momentum in the anterior-posterior direction during pitching (r = 0.68). Lean body mass and body mass showed statistically significant correlations with both of the 2 linear momentums during pitching (r = 0.71∼0.83), and concentric impulse in CMJ (r = 0.71 and 0.81). Pelvis and trunk pitching mechanics did not correlate with any of the CMJ variables at the statistically significant level, whereas the direction of the correlations varied (|r| < 0.45). Assessment of a baseball pitcher's CMJ should focus on concentric impulse and peak power because only these showed meaningful relationships with fastball velocity or momentum generation during pitching. An increase in lean body mass is also suggested to be able to generate more impulse and momentum. Baseball coaches, strength coaches, and clinicians are encouraged to include lower-body explosive training to enhance the force and power output capacity of baseball pitchers.

Unsupervised Machine Learning inCountermovement Jump andIsometric Mid-Thigh Pull Performance Produces Distinct Combat andPhysical Fitness Clusters inMale andFemale U.S. Marine Corps Recruits.

Several challenges face the U.S. Marine Corps (USMC) and other services in their efforts to design recruit training to augment warfighter mobility and resilience in both male and female recruits as part of an integrated model. Strength and power underpin many of the physical competencies required to meet the occupational demands one might face in military. As the military considers adopting force plate technology to assess indices of strength and power, an opportunity presents itself for the use of machine learning on large datasets to deduce the relevance of variables related to performance and injury risk. The primary aim of this study was to determine whether cluster analysis on baseline strength and power data derived from countermovement jump (CMJ) and isometric mid-thigh pull (IMTP) adequately partitions men and women entering recruit training into distinct performance clusters. The secondary aim of this study is then to assess the between-cluster frequencies of musculoskeletal injury (MSKI). Five hundred and sixty-five males (n = 386) and females (n = 179) at the Marine Corps Recruit Depots located at Parris Island and San Diego were enrolled in the study. Recruits performed CMJ and IMTP tests at the onset of training. Injury data were collected via medical chart review. Combat fitness test (CFT) and physical fitness test (PFT) results were provided to the study team by the USMC. A k-means cluster analysis was performed on CMJ relative peak power, IMTP relative peak force, and dynamic strength index. Independent sample t-tests and Cohen's d effect sizes assessed between-cluster differences in CFT and PFT performance. Differences in cumulative incidence of lower extremity %MSKIs were analyzed using Fisher's exact test. Relative risk and 95% confidence intervals (CIs) were also calculated. The overall effects of cluster designation on CMJ and IMTP outcomes ranged from moderate (relative peak power: d = -0.68, 95% CI, -0.85 to -0.51) to large (relative peak force: d = -1.69, 95% CI, -1.88 to -1.49; dynamic strength index: d = 1.20, 95% CI, 1.02-1.38), indicating acceptable k-means cluster partitioning. Independent sample t-tests revealed that both men and women in cluster 2 (C2) significantly outperformed those in cluster 1 (C1) in all events of the CFT and PFT (P < .05). The overall and within-gender effect of cluster designation on both CFT and PFT performance ranged from small (d > 0.2) to moderate (d > 0.5). Men in C2, the high-performing cluster, demonstrated a significantly lower incidence of ankle MSKI (P = .04, RR = 0.2, 95% CI, 0.1-1.0). No other between-cluster differences in MSKI were statistically significant. Our results indicate that strength and power metrics derived from force plate tests effectively partition USMC male and female recruits into distinct performance clusters with relevance to tactical and physical fitness using k-means clustering. These data support the potential for expanded use of force plates in assessing readiness in a cohort of men and women entering USMC recruit training. The ability to pre-emptively identify high and low performers in the CFT and PFT can aid in leadership developing frameworks for tailoring training to enhance combat and physical fitness with benchmark values of strength and power.

Physical Profiles of All-Rounders, Batters, and Bowlers in Sub-Elite Women's Cricket.

Jacobs, J, Olivier, B, Brandt, C, and Jafta, G. Physical profiles of all-rounders, batters, and bowlers in sub-elite women's cricket. J Strength Cond Res 38(6): 1095-1102, 2024-The unique physical profile of each player's role in sub-elite women's cricket is vital for optimizing performance as these players progress to the elite levels. This quantitative, cross-sectional study investigates the physical profiles of sub-elite women's cricket players as a group and compares these profiles across different player roles. Sub-elite female cricket players in the South African domestic women's cricket league were included in this study. A battery of physical assessments were conducted at the start of the 2022/23 season. The physical assessments included body composition, individual muscle strength testing using dynamometry, 2-km time trial (TT), countermovement jump (CMJ), single-leg jump (SLJ), isometric mid-thigh pull, push-up, and hop test on force plates. A total of 44 female players (20.86 ± 1.6 years) were included in the study. Differences were found in muscle mass (p = 0.004) and peak power (p = 0.040) for all-rounders and bowlers. Player roles presented with different dominant (p = 0.006) and non-dominant (p = 0.066) knee flexion strength. The bowlers' body composition and physical strength profile are compromised compared with batters and all-rounders. There were several physical strength and power differences between pace and spin bowlers in CMJ and SLJ tests for jump height (p = 0.009) and peak power (p = 0.006). Batters performed the best in the 2-km TT. Body composition and musculoskeletal profiles for each player role can be baseline markers in sub-elite women's cricket. Stakeholders can use this information to guide physical preparation for players advancing to elite levels.

Can the Countermovement Jump or Squat Jump predict the kinematic performance of the rear Bandal Chagi kick?

This study aimed to measure the associative and predictive strength of biomechanical variables of the countermovement jump (CMJ) and squat jump (SJ), and performance of the bandal-chagi kick performed with the dominant (D) rear lower limb in elite Taekwondo Athletes. For this, a total of 27 international level athletes (15 males and 12 females) performed the CMJ and SJ on two force platforms. The bandal-chagi was monitored using a motion capture system (VICON). The main results indicated that non-dominant (ND) Stiffness for the CMJ showed predictive power alone (p=0.048) or in combination with eccentric breaking rating of force development (RFD) (p=0.031) for total hip angular speed. Takeoff peak force/BM for the SJ predicted total time (p=0.002). Concentric RFD/BM predicted total linear foot acceleration, either alone (p=0.001) or with vertical speed at takeoff (p=0.042). The total hip angular acceleration predictor was takeoff peak force D alone (p=0.019) or in combination with peak power/BM (p=0.041). In conclusion, CMJ and SJ tests showed specific associations with TKD kick performance. These analyses in this study indicated that they are good predictors for TKD athletes, producing results consistent with the participants’ levels. Keywords: Martial arts, Biomechanical Phenomena, Time-motion studies, Kinanthropometry, Motion Capture.

Countermovement-Jump and Pull-Up Performance Before and After a Swimming Race in Preparatory and Competitive Phases of a Swimming Season.

Monitoring performance athletes' training responses can be efficiently completed at competitive events. This study aimed to explore the changes in swimming, countermovement-jump (CMJ), and pull-up (PU) performance following training across a competitive phase, as well as immediately before and after each race. Fourteen well-trained male sprint/middle-distance swimmers (height 179 [7]cm, mass 70 [8]kg, age 18 [2]y), from 3 regional training groups, completed CMJ and PU tests before and after the national competitions in October and May, when race performance was also assessed. Swimming race performance was significantly improved from before the national competitions in October to after the national competitions in May (1.8% [3.2%], P = .044, d = 0.60, moderate effect). Although there were no significant changes in PU velocity, CMJ performance significantly improved from before the national competitions in October to after the national competitions in May (mean difference 2.29cm, P = .004, d = 3.52) and showed before-to-after race decreases (mean difference -1.64cm, P = .04, d = 2.28). Swimming performance and CMJ performance improved as the season progressed, although these improvements were not directly correlated. PU performance did not appear to be sensitive to training or race-induced fatigue, in contrast to CMJ, in this group of male swimmers.

Effects of focal vibration on changes in sports performance in amateur athletes: A randomized clinical trial.

The aim of this study was to evaluate the effectiveness of a focal vibration protocol added to an activation protocol with active muscle contractions and to see what repercussions it has on sprint, countermovement jump (CMJ), and lower limb isometric strength. A double-blind randomized clinical trial was conducted in the Functional Anatomy Laboratory and the sample consisted of 70 athletes. The main outcome measures were knee extension force, CMJ, sprint, and surface electromyography. Repeated-measures analysis of variance revealed significant improvements. They were found in the within-group analysis for the Experimental Group in the isometric extension force (p < 0.001; η2 = 0.368), CMJ (p < 0.001; η2 = 0.301) and 30 m sprint (p < 0.001; η2 = 0.376). In the electromyography, there are changes in the Sham Group in all muscles, in CMJ and Sprint tests, and no differences in the Experimental Group, except for the RF muscle. In the between-group analysis, statistically significant differences were found only in favor of the Experimental Group in CMJ (p = 0.017; η2 = 0.81) and 30 m sprint (p < 0.001; η2 = 0.152). These results confirm a significant improvement in the sprint, CMJ performance, and quadriceps strength, after a focal vibration protocol, added to a muscle active contraction, compared to a focal vibration sham protocol. Therefore, our results suggest that the focal vibration can be a very useful tool in sports involving high-powered actions.

Test-retest reliability of lower limb muscle strength, jump and sprint performance tests in elite female team handball players.

This study aimed to assess the reliability of lower limb muscle function (knee extensor/flexor peak torque, rate of torque development (RTD), impulse, and countermovement jump (CMJ) performance) and sprint performance (acceleration capacity). CMJ performance was evaluated on a force plate. MVIC, RTD and impulse variables were investigated using a portable isometric dynamometer and sprint performance was assessed with dual-beam photocells in elite female athletes. CMJ test variables maximal vertical jump height, peak and mean power, concentric work, and body center of mass displacement demonstrated good-to-excellent test-retest correlations between Test 1 and Test 2 (ICC ≥ 0.70, CWw-s = 3.4-11.0%). Peak MVIC torque for the knee extensors and flexors demonstrated excellent test-retest correlations (both ICC = 0.84) along with CVw-s values of 6.8 and 6.0%, respectively. Late-phase (0-100ms, 0-200ms) RTD for the knee flexors demonstrated excellent test-retest correlations (ICC = 0.89-0.91, CVw-s = 4.8-8.5%). Sprint times at 10- and 20-m demonstrated excellent test-retest reproducibility (ICC = 0.83 and ICC = 0.90, respectively) with CVw-s values of 1.9 and 1.5%. For 5-m sprint times, test-retest reproducibility was good (ICC = 0.71) with CVw-s of 2.8%. Sprint testing performed while dribbling a handball improved (p < 0.05) from test to retest at 5-, 10- and 20-m. In conclusion, the force plate, the mobile isometric dynamometer, and dual-beam photocells provide reproducible tools for field-based testing of countermovement jump performance, knee extensor and flexor strength and sprint performance.

Female National Collegiate Athletic Association Division-I Athlete Injury Prediction by Vertical Countermovement Jump Force-Time Metrics.

Merrigan, JJ, Stone, JD, Kraemer, WJ, Vatne, EA, Onate, J, and Hagen, JA. Female National Collegiate Athletic Association Division-I athlete injury prediction by vertical countermovement jump force-time metrics. J Strength Cond Res 38(4): 783-786, 2024-Vertical countermovement jump (CMJ) assessments on force plates have been purported to screen for musculoskeletal injury risk (MSKI) but with little scientific support. Thus, this study aimed to identify associations and noncontact lower-body injury predictability with CMJ force-time metrics in female athletes. The study entailed a retrospective analysis of routine injury and performance monitoring from 155 female National Collegiate Athletics Association Division I athletes. Noncontact lower-body injuries included in analysis were confirmed by medical staff, occurred during competition or training, resulted in time loss from training, and occurred within 3 months following CMJ testing (2 maximal effort, no arm swing, jumps on dual force plates). A total of 44 injuries occurred within 3 months following CMJ baseline testing and resulted in an average of 24.5 missed days from training. Those who sustained an injury were more likely to sustain another injury (15 of 44 injuries [33.1%]; odds ratio = 3.05 [95% CI = 1.31-6.99]). For every 1-unit increase from the mean in eccentric mean power and minimum eccentric force, there was a decrease in odds of sustaining a MSKI. Despite high overall model accuracy (85.6%), the receiving operating characteristic area under the curve (65.9%) was unacceptable and the true positive rate (recall) was 0.0%. Thus, no injuries in the testing data set were correctly classified by the logistic regression model with CMJ force-time metrics as predictors. Baseline CMJ assessment may not be useful for noncontact lower-body musculoskeletal injury screening or predictability in National Collegiate Athletics Association female athletes.

Dose-Response Effect of an Inertia Flywheel Postactivation Performance Enhancement Protocol on Countermovement Jump Performance.

The purpose of this study was to investigate the dose-response effect of a high-load, 6-repetition, maximum effort inertial flywheel (IFw) squat postactivation performance enhancement (PAPE) protocol on countermovement jump (CMJ) performance metrics. Thirteen subjects completed 5 squat testing sessions: 1 session to determine back-squat 6-repetition maximum, 1 session to determine 6-repetition maximum IFw load, and 3 sessions to investigate the dose-response effect of an IFw PAPE protocol set at the load determined in the second session. In the IFw PAPE sessions, subjects completed either 1, 2, or 3 sets of IFw squats, then performed 5 CMJs over 12minutes (1, 3, 6, 9, and 12min post-IFw). All CMJ tests were conducted on a force platform where CMJ performance outcomes and impulse variables were calculated. There was no main time or volume effect for jump height, contact time, reactive strength index, peak force, or any of the impulse variables. A main time effect was identified for flight time (P = .006, effect size = 0.24) and peak power (P = .001, effect size = 0.28). The lack of change in jump height may indicate that too much fatigue was generated following this near-maximal IFw squat protocol, thereby reducing the PAPE effect.

The Relationship Between Maximum Lower Limb Strength &amp; Power, and GPS Acceleration Speed in Elite U20 Gaelic Football Athletes

Previous research indicates positive relationships between high levels of lower limb strength and power, and acceleration sprint velocity in team sport athletes. This cross-sectional study aimed to investigate the relationship between lower limb absolute and relative strength, countermovement jump (CMJ) height, and Global Positioning System (GPS) recorded 20m acceleration sprint velocity in elite male U-20 Gaelic football athletes. Nineteen athletes (19.0 ± 0.5 years; 81.1 ± 5.5 kg; 182 ± 6.2 cm) from the same elite U-20 squad participated in this study during an in-season period. Subjects performed a &gt;95% 1RM box squat, a 20m sprint test, and a CMJ test. Relative maximum lower limb strength (r = 0.54, 95% CI [0.11 to 0.8]; p &lt; 0.05) and CMJ height (r = 0.66, 95% CI [0.29 to 0.86]; p &lt; 0.001) showed strong correlations with 20m sprint velocity. A multiple linear regression analysis demonstrated that lower limb maximum relative strength and CMJ height significantly predicted 20m sprint velocity (Adjusted R2 = 0.51, F (2, 16) = 6.29, p &lt; 0.05). These findings provide evidence for the importance of elite under-age Gaelic football athletes acquiring high levels of lower limb strength and power characteristics to enhance acceleration sprint performance.

A comparative study of lower limb strength during vertical jump of male college students in table tennis, badminton and tennis

The objectives of this paper are to explore the correlation of kinetic indices of SJ (squat jump) and CMJ (counter-movement jump) and the differences of lower limb strength mechanics indexes of table tennis, badminton and tennis players under SJ and CMJ. This study included 60 male collegiate athletes, 20 each from table tennis, badminton, and tennis. Subjects performed SJ and CMJ tests on a force platform and the vertical jump data were analyzed. Table tennis, badminton and tennis players demonstrated significant differences in the SJ and CMJ assessments. Badminton players outperformed table tennis players in terms of peak power (PP) (p = 0.005) and peak velocity (PV) (p = 0.017). Badminton players beat table tennis players in PV (p = 0.028), PP (p = 0.022), fast twitch fibers (FTF) (p = 0.033) and pre-stretch effect (EP) (p = 0.0004). Tennis players exhibited lower peak force (PF) (p = 0.006) indicators than badminton players. For athletes in all three sports, the SJ test markers (vertical jump displacement, PF, PP and PV) demonstrated a strong positive correlation. There was a highly significant positive correlation between VJD and PF, PP, PV and FTF among badminton players. Significant positive connections were discovered between PF, PP, PV, FTF and EP, as well as between PP and PV and FTF and EP. PV and FTF had a very strong positive correlation, as did EP, PV and FTF. College badminton players had higher vertical jumps than table tennis and tennis players. In addition to vertical jump height, PP (power production), PV (power velocity) and FTF (force-time factors) are important markers for assessing the success of vertical jumps in athletes’ daily training. These findings can assist coaches and athletes develop better vertical jump training programs.

The Countermovement Rebound Jump: Between-Session Reliability and a Comparison With the Countermovement and Drop Jump Tests.

Xu, J, Turner, A, Comyns, TM, Chavda, S, and Bishop, C. The countermovement rebound jump: Between-session reliability and a comparison with the countermovement and drop jump tests. J Strength Cond Res 38(4): e150-e159, 2024-The countermovement jump (CMJ) and drop jump (DJ) are widely used jump tests to evaluate an athlete's neuromuscular performance. Nevertheless, conducting both the CMJ and the DJ assessments during one testing session can demand a considerable time investment that practitioners or coaches might not always have available. This study investigated whether the countermovement rebound jump (CMRJ) could be considered a viable alternative to the CMJ and DJ tests, respectively. Thirty-three physically active students volunteered as subjects (age: 27.2 ± 5.9 years, height: 1.78 ± 0.8 cm, body mass: 77.5 ± 11.5 kg), with 18 jumps completed for each subject across 2 testing sessions. The jump height (JH) and strategy-based metrics (time to take-off [TTTO], countermovement depth [CM depth], and reactive strength index [RSI] modified for CMJ and the first jump of the CMRJ; leg stiffness [ Kleg ], ground contact time [GCT], and RSI for DJ and the second jump for the CMRJ) were calculated simultaneously via the impulse-momentum, flight time, double integration, and motion capture methods. All variables were examined by repeated-measures analysis of variance, 2-way random effects model intraclass correlation coefficient (ICC), coefficient of variation (CV), and standard error of measurement, with the significance set at p ≤ 0.05. All 3 jump tests showed good-to-excellent relative reliability (ICC = 0.79-0.98) and good-to-moderate CV (≤9.83), with the only exception being Kleg measured during the DJ and in the second jump of the CMRJ assessment (CV ≤ 16.01%). Of all measured metrics, significant differences were only observed regarding TTTO between jumps ( p ≤ 0.027, effect size [ES] ≤ 0.49). The comparison of calculation methods indicated that the JH calculated by 4 methods were not significantly different between jump actions ( p ≥ 0.254). These findings support the use of the CMRJ as a reliable alternative to the CMJ and DJ tests. However, practitioners should be mindful of using Kleg as a metric, whereas practitioners are also advised to allocate sufficient familiarization trials before implementing the CMRJ into their routine test batteries.

Mental fatigue impairs repeated sprint and jump performance in team sport athletes

ObjectivesWe tested whether mental fatigue (MF), induced by a cognitively-demanding task, would impair repeated sprint ability (RSA) and repeated jump ability (RJA) performance, and whether physical fatigue and MF would impair psychomotor vigilance. DesignRandomized within-participant design. MethodsAfter establishing baseline peak countermovement jump (CMJ), 18 male participants performed 12 maximal 20-m (10-m linear + 10-m directional) repeated sprints (RSA random test) followed by 12 maximal repeated CMJs (RJA test) subsequent to 30-min Stroop task (MF) or a documentary (Control). Peak and mean running time and height, percent decrement score (Sdec), blood lactate, heart rate and RPE were measured for CMJ, RSA, and RJA tests. MF (M-VAS) and psychomotor vigilance [psychomotor vigilance test (PVT)] were measured at baseline, after each condition, and after the RSA/RJA tests. ResultsCompared to Control, the Stroop task elevated MF (p = .001), RPE ratings (all p < .031), and mean and Sdec performance in directional (but not linear) RSA (all p < .032) and RJA tests (all p < .034). PVT score worsened after Stroop task (p = .011) but not Control, declined after RSA/RJA tests in both conditions (all p < .023) and was lower in the MF condition (p = .029). No condition differences were noted for peak (CMJ, RSA and RJA tests) performance, blood lactate, and heart rate. ConclusionsMF impairs directional RSA, and RJA performance. This impairment was linked with increased RPE and without physiological changes. The progressive impairment in PVT score suggests a cumulatively negative effect of mental and physical fatigue on psychomotor vigilance.