Countermovement Jump Research Articles

Effects of far-infrared radiation lamp therapy on recovery from a simulated soccer-match in elite female soccer players.

We investigated the effects of far-infrared radiation (FIR) lamp therapy on changes in muscle damage and performance parameters following six sets of 15-min Loughborough intermittent shuttle test (LIST), a simulated soccer match. Twenty-four elite female soccer players (20-24 y) were assigned into FIR or sham treatment group (n = 12/group). The participants received a 60-min FIR or sham treatment (30 min per muscle) over knee extensors (KE) and flexors (KF) at 2, 25, 49, 73, and 97 h post-LIST. Maximal voluntary isometric contraction (MVC) torque and muscle soreness of the KE and KF, plasma creatine kinase (CK) activity as muscle damage markers, and several performance parameters including countermovement jump (CMJ) and Yo-Yo intermittent recovery test level 1 (YYIR1) were measured before and 1, 24, 48, 72, 96, and 120 h post-LIST. Changes in the measures were compared between groups by a mixed-design two-way ANOVA. The running distance covered during LIST and changes in the measures at 1-h post-LIST (before the treatment) were similar (p = 0.118-0.371) between groups. Changes in muscle damage markers at 24-120 h post-LIST were smaller (p < 0.05, η2 = 0.208-0.467) for the FIR (e.g., MVC-KE torque decrease at 48-h post-LIST: -1 ± 2%, peak KE soreness: 16 ± 10 mm, peak CK: 172 ± 42 IU/L) than sham group (-11 ± 9%, 33 ± 7 mm, 466 ± 220 IU/L, respectively). Performance parameters recovered faster (p < 0.05, η2 = 0.142-0.308) to baseline for the FIR (e.g., decreases at 48-h post-LIST; CMJ: 0 ± 1%, YYIR1: 0 ± 1%) than sham group (-6 ± 2%, -9 ± 6%, respectively). These results suggest that the FIR lamp therapy was effective for enhancing recovery from a soccer match.

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.

Nocturnal Smartphone Use Affects Sleep Quality and Cognitive and Physical Performance in Tunisian School-Age Children.

Nocturnal smartphone use emits blue light, which can adversely affect sleep, leading to a variety of negative effects, particularly in children. Therefore, the present study aimed to determine the effect of acute (AC) (one night) and repeated (RC) (five nights) nocturnal smartphone exposure on sleep, cortisol, and next-day performance in Tunisian children. Thirteen participants (seven girls and six boys, age 9 ± 0.6, height 1.32 ± 0.06, weight 34.47 ± 4.41) attended six experimental nights. The experiment started with a baseline night (BL) with no smartphone exposure, followed by repeated sessions of nocturnal smartphone exposure lasting 90 minutes (08:00 pm-09:30 pm). Actigraphy; salivary cortisol; the Stroop test (selective attention); choice reaction time (CRT); N-back (working memory); counter-movement jump (CMJ), composed of flight time (time spent in the CMJ flight phase) and jump height; and a 30 m sprint were assessed the morning after each condition. Both AC and RC shortened total sleep time (TST) (p < 0.01), with a greater decrease with RC (-46.7 min, ∆% = -9.46) than AC (-28.8 min, ∆% = -5.8) compared to BL. AC and RC significantly increased waking after sleep onset (3.5 min, ∆% = 15.05, to 9.9 min, ∆% = 43.11%) and number of errors made on the Stroop test (1.8 error, ∆% = 74.23, to 3.07 error, ∆% = 97.56%). Children made 0.15 and 0.8 more errors (∆% = 6.2 to 57.61%) and spent 46.9 s and 71.6 s more time on CRT tasks (∆% = 7.22 to 11.11%) with AC and RC, respectively, compared to BL. The high-interference index of the Stroop task, CMJ performance, and 30 m sprint speed were only altered (p < 0.01) following RC (0.36, Δ% = 41.52%; -34 s, Δ% = -9.29%, for flight time and -1.23 m, -8.72%, for jump height; 0.49 s, Δ% = 6.48, respectively) when compared to BL. In conclusion, one- or five-night exposure to smartphones disturbed the children's sleep quality and their performance, with more pronounced effects following RC.

Body composition, anaerobic power, lower extremity strength in football players: Acute effect on different leagues

The aim of the study was to compare differences in body composition, lower extremity strength, and anaerobic power characteristics among professional football players at different league levels. A total of seventy-one volunteer players aged between eighteen and thirty-five years (mean age: 23.14 ± 4.23 years) participated in the study, representing the Super League, 1st League, and 2nd League. The participants' body compositions were measured using the DXA (Hologic QDR Series, Delphi A model, Bedford, MA, USA) bioelectrical impedance analyzer, CounterMovement Jump (CMJ) strength with the ChronoJump Smartspeed Mat (INEFC, Barcelona), and Running Anaerobic Sprint Test (RAST) tests were conducted. ANOVA was used to compare multiple groups, and the Duncan multiple comparison tests were conducted in cases where differences were observed to determine which group the difference favored. The results revealed that Super League players statistically possessed more significant values in body composition compared to 1st and 2nd League players and demonstrated significantly higher values in terms of jump height, maximum force output, and anaerobic power compared to 1st and 2nd League players (p

Influence of Isometric and Dynamic Fatiguing Protocols on Dynamic Strength Index

Background: Strength and conditioning experts widely recognize the dynamic strength index (DSI) as a tool for assessing an athlete’s ability to utilize strength in dynamic actions. The DSI is calculated as the ratio of peak force in dynamic actions versus isometric ones. To date, the influence of fatigue on the DSI is still not fully understood. This study aimed to explore the effects of both dynamic and isometric fatigue tasks on the DSI. Methods: A total of 24 physically active participants underwent fatigue tests involving repeated countermovement jumps (dynamic) and repeated isometric mid-thigh pulls (isometric) in separate visits. Results: The results revealed a marked drop in performance, with dynamic force showing a more significant reduction (p &lt; 0.001; d = 1.57) than isometric force (p = 0.015; d = 0.30). After the isometric fatigue task, the DSI increased, indicating a more substantial decline in isometric force (p &lt; 0.001; d = 1.75) compared to dynamic force (p = 0.313; d = 0.08). Following this trend, the DSI decreased post-dynamic fatigue (p &lt; 0.001; d = 0.99) and increased post-isometric fatigue (p &lt; 0.001; d = 3.11). Conclusion: This research underscores the need to consider fatigue’s task-specific effects on the DSI, enabling more tailored training methodologies for athletes.

Acute physiological responses and muscle recovery in females: a randomised controlled trial of muscle damaging exercise in hypoxia

BackgroundStudies have investigated the effects of training under hypoxia (HYP) after several weeks in a male population. However, there is still a lack of knowledge on the acute hypoxic effects on physiology and muscle recovery in a female population.MethodsThis randomized-controlled trial aimed to investigate the acute effects of muscle damaging exercise, performed in HYP and normoxia (CON), on physiological responses and recovery characteristics in healthy females. Key inclusion criteria were recreationally active female participants between the age of 18 to 35 years without any previous surgeries and injuries, whilst key exclusion criteria were acute pain situations, pregnancy, and medication intake. The females conducted a muscle-damaging protocol, comprising 5 × 20 drop-jumps, in either HYP (FiO2: 12%) or CON (FiO2: 21%). Physiological responses, including capillary oxygenation (SpO2), muscle oxygenation (SmO2), heart rate (HR), core- (Tcore) and skin- (Tskin) temperature were assessed at the end of each exercise set. Recovery characteristics were quantified by taking venous blood samples (serum creatine-kinase [CK], C-reactive protein [CRP] and blood sedimentation rate [BSR]), assessing muscle swelling of the quadriceps femoris muscle, maximum voluntary isometric contraction (MVIC) of the knee extensor muscles, countermovement jump (CMJ) performance and muscle soreness ratings (DOMS) at 24-, 48- and 72-hrs post-exercise.ResultsSpO2 (HYP: 76.7 ± 3.8%, CON: 95.5 ± 1.7%, p < 0.001) and SmO2 (HYP: 60.0 ± 9.3, CON: 73.4 ± 5.8%, p = 0.03) values were lower (p < 0.05) in HYP compared to CON at the end of the exercise-protocol. No physiological differences between HYP and CON were observed for HR, Tcore, and Tskin (all p > 0.05). There were also no differences detected for any recovery variable (CK, CRP, BSR, MVIC, CMJ, and DOMS) during the 72-hrs follow-up period between HYP and CON (all p > 0.05).ConclusionIn conclusion, our results showed that muscle damaging exercise under HYP leads to reduced capillary and muscle oxygenation levels compared to normoxia with no difference in inflammatory response and muscle recovery during 72 h post-exercise.Trial registrationNCT04902924, May 26th 2021.

Effects of bi-hemispheric anodal transcranial direct current stimulation on soccer player performance: a triple-blinded, controlled, and randomized study.

The search for increased performance and physical performance are linked to the use of ergogenic resources. The vertical jump is one of the measures commonly used to evaluate the performance of lower limbs in athletes. Transcranial direct current stimulation (tDCS) is a non-invasive, safe, economically viable technique that can modulate cortical excitability, which can influence the increase in the performance of athletes in general. This study aimed to investigate whether the use of tDCS on the primary motor cortex (M1) improves the performance of soccer players. A cross-sectional study was conducted. Twenty-seven players were randomized into three groups: Active tDCS group (n = 9), Sham group (n = 9), and control group (n = 9). Stimulation was applied at 2 mA for 15 min using a cephalic mount. Visual Pain Scale (VAS) and Subjective Recovery Scale (SRS) were monitored before and after tDCS. In addition, the participants performed the Countermovement Jump (CMJ) before and after the stimulation intercalated with Heart Rate (HR) and Rating of Perceived Exertion (RPE CR-10). No differences were found in any of the performance variables analyzed (p > 0.05) nor in the responses of HR (p > 0.05), RPE (p > 0.05), VAS (p > 0.05), and SRS (p > 0.05) between groups. The tDCS in M1 did not change the performance of the vertical jump, and there was no improvement in the subjective scales. New studies should also be developed with different stimulus intensities in different cortical areas and sports modalities.

Assessing Jump Performance: Intra- and Interday Reliability and Minimum Difference of Countermovement Jump and Drop Jump Outcomes, Kinetics, Kinematics, and Jump Strategy

Understanding the reliability of jump testing is essential to determine the neuromuscular progress of athletes and make informed decisions. This study aimed to assess the reliability of several countermovement jump (CMJ) and drop jump (DJ) test metrics in female volleyball players. Sixteen (n = 16) semi-professional female volleyball players participated in this test-retest study. Intrasession and intersession reliability of CMJ and DJ metrics were evaluated using a randomized cross-over design. A dual force platform was used to collect CMJ and DJ data, and several dependent variables were calculated using forward dynamics. Intraclass correlation coefficients (ICC), coefficients of variation (CV), and minimum difference (MD) were calculated to assess intra- and interday reliability. During the same testing, the third attempt consistently yielded the highest values for both tests in jump height but presented excellent reliability (CMJ: ICC [95%CI] = 0.97 [0.93–0.99]; CV [95%CI] = 4.1% [1.2–7.0]; MD95 = 3.5 cm; MD90 = 2.9 cm; DJ: ICC [95%CI] = 0.91 [0.77–0.97]; CV [95%CI] = 6.7% [1.9–11.5]; MD95 = 6.0 cm; MD90 = 5.0 cm). CMJ height exhibited excellent reliability between sessions (ICC [95%CI] = 0.93 [0.81–0.97]; CV [95%CI] = 3.8% [1.1–6.4]; MD95 = 3.5 cm; MD90 = 3.0 cm), whereas DJ height demonstrated slightly lower but still acceptable intersession reliability (ICC [95%CI] = 0.81 [0.55–0.93]; CV [95%CI] = 6.1% [1.7–10.4]; MD95 = 5.2 cm; MD90 = 4.4 cm). Intersession reliability for CMJ kinetics and kinematics was excellent for 13 of the 24 metrics assessed. For DJ, only concentric (ICC [95%CI] = 0.91 [0.76–0.97]; CV [95%CI] = 3.0% [0.9–5.2]; MD95 = 15 Ns; MD90 = 12.6 Ns) and eccentric impulses (ICC [95%CI] = 0.99 [0.96–0.99]; CV [95%CI] = 1.7% [0.5–2.9]; MD95 = 9.2 Ns; MD90 = 7.7 Ns) demonstrated excellent intersession reliability. Most CMJ variables showed excellent reliability within sessions, while DJ had lower reliability in most metrics. These findings provide valuable information to physical trainers to select the metrics to assess athletes’ performance as well as to identify a minimum cut-off value that serves as a reference for each of the metrics reported in both tests.

Effects of plyometric training techniques on vertical jump performance of basketball players.

The aim of our study was to compare the effects of two different plyometric training programs (targeting knee extensors or plantar flexors) on jump height and strength of leg muscles. Twenty-nine male basketball players were assigned to the knee-flexed (KF), knee-extended (KE), or control groups. In addition to regular training, the KF group performed plyometric jumps (10 sets of 10 jumps, 3 sessions/week, 4weeks) from 50cm boxes with the knee flexed (90°-120°), whereas the KE group performed the jumps from 30cm boxes with the knee much more extended (130°-170°). Jumping ability was evaluated with squat jumps (SJs), countermovement jumps (CMJs), and drop jumps from 20cm (DJ20) and 40cm (DJ40). Knee and ankle muscles were assessed during maximal isokinetic and isometric tests, and EMG activity was recorded from vastus lateralis and medial gastrocnemius. The KF group increased SJ (+10%, d=0.86) and CMJ (+11%, d=0.70) but decreased DJ40 height (-7%, d=-0.40). Conversely, the KE group increased DJ20 (+10%, d=0.74) and DJ40 (+12%, d=0.77) but decreased SJ height (-4%, d=-0.23). The reactivity index during DJs increased (+10% for DJ20, d=0.47; +20% for DJ40, d=0.91) for the KE group but decreased (-10%, d=-0.48) for the KF group during DJ40. Plantar flexor strength increased for the KE group (d=0.72-1.00) but not for the KF group. Negative transfer across jumps is consistent with the principle of training specificity. Basketball players interested to perform fast rebounds in their training should avoid plyometric jumps with large knee flexions and long contact times.

The effect of flywheel complex training with eccentric-overload on muscular adaptation in elite female volleyball players.

This study aimed to compare the effects of 8 weeks (24 sessions) between flywheel complex training with eccentric overload and traditional complex training of well-trained volleyball players on muscle adaptation, including hypertrophy, strength, and power variables. Fourteen athletes were recruited and randomly divided into the flywheel complex training with an eccentric-overload group (FCTEO, n=7) and the control group (the traditional complex training group, TCT, n=7). Participants performed half-squats using a flywheel device or Smith machine and drop jumps, with three sets of eight repetitions and three sets of 12 repetitions, respectively. The variables assessed included the muscle thickness at the proximal, mid, and distal sections of the quadriceps femoris, maximal half-squats strength (1RM-SS), squat jump (SJ), countermovement jump (CMJ), and three-step approach jump (AJ). In addition, a two-way repeated ANOVA analysis was used to find differences between the two groups and between the two testing times (pre-test vs. post-test). The indicators of the FCTEO group showed a significantly better improvement (p<0.05) in CMJ (height: ES = 0.648, peak power: ES = 0.750), AJ (height: ES = 0.537, peak power: ES = 0.441), 1RM-SS (ES = 0.671) compared to the TCT group and the muscle thicknes at the mid of the quadriceps femoris (ES = 0.504) after FCTEO training. Since volleyball requires lower limb strength and explosive effort during repeated jumps and spiking, these results suggest that FCTEO affects muscular adaptation in a way that improves performance in well-trained female volleyball players.

Unilateral Hamstring Muscle Strengthening Exercises Can Improve Hamstring Asymmetry and Increase Jumping Performance in Sub-Elite Badminton Athletes

This study aimed to determine the effect of 10 weeks of unilateral training on asymmetry and jumping performance in sub-elite badminton athletes. 23 out of 41 badminton athletes who met the inclusion criteria were taken as samples in this study. Selected samples will be given unilateral exercise interventions in the form of Swiss ball hamstring curl exercises and single leg bridge for ten weeks with a frequency of exercise 3 times a week. Data were collected two times before the intervention (pretest) was given and after the intervention (posttest). The measurement uses the Norbord test to determine the condition of hamstring asymmetry and the Counter Movement Jump (CMJ) jump test to determine jump height. The results showed that there was a significant decrease in the percentage of hamstring asymmetry p ≤ 0.001 (Pretest: 20.26±10.25 % to Posttest: 9.20±3.51 %) and has a large effect size with a Cohen's d value of 1.443, and an increase in jump height p ≤ 0.001 (Pretest: 33.06±4.93 cm to Posttest: 35.17±4.54 cm) and has a medium effect size with a Cohen's d value of 0.447. The conclusion is that 30 unilateral exercises for ten weeks can improve hamstring asymmetry above 10% and increase jumping performance in badminton athletes. Keywords: Hamstring Asymmetry, Jump performance, Unilateral exercise

Exploring Indicators for Training Load Control in Young Swimmers: The Role of Inspiratory Spirometry Outcomes.

One of the most important implications of technology in swimming is to control training loads. Lactate control, video-analysis of the technique or the assessment of specific actions, i.e., the vertical jump, have helped to provide load adaptation indicators in swimmers in recent decades. However, these indicators have led to a longer application time, due to their indirect procedure and the need to analyze each variable. The aim of this study was to analyze whether inspiratory spirometry values can serve as a training load control tool in swimmers. Countermovement jump (CMJ), Inspiratory Force Index (S-INDEX) and Peak Inspiratory Flow (PIF) were evaluated with a load of 3 cm H2O before, during and after performing a swimming performance test (critical speed test: specific warming up, 400 m and 100 m freestyle). Positive correlations were found between S-INDEX and jump height after warm-up, after 400 m and at the end of 100 m (Spearman = 0.470, R2 = 0.280; Spearman = 0.508, R2 = 0.392; Spearman = 0.458, R2 = 0.359, p < 0.05, respectively). Moreover, positive correlations were also found between PIF and jump height at the same evaluated moments (Spearman = 0.461, R2 = 0.305; Spearman = 0.493, R2 = 0.386; Spearman = 0.454, R2 = 0.374, p < 0.05). Both the S-INDEX and the PIF could serve as useful tools for swimmer load control, allowing coaches to make more immediate decisions.

The Relationship Between the Isometric Squat and Stretch Shortening Cycle Function and Sprint Acceleration Performance in Hurling Players.

Brady, CJ, Harrison, AJ, Flanagan, EP, Haff, GG, and Comyns, TM. The relationship between the isometric squat and stretch shortening cycle function and sprint acceleration performance in hurling players. J Strength Cond Res 38(6): e288-e298, 2024-The primary aim was to examine the relationship between sprint acceleration performance and the performance tests: isometric squat (ISqT), countermovement jump (CMJ), and reactive strength index (RSI). The secondary aim determined whether these tests could distinguish between sprint performance levels. Twenty-six male under-21 subjects completed the ISqT, with peak force (PF), relative PF, force at 100, 150, and 200 milliseconds (ms), and impulse (0-200 ms) measured. Jump height (JH) was calculated from the CMJ and RSI during the 10-5 repeated jump test. Subjects completed 3 × 30-m sprints with splits taken at 5, 10, 20, and 30 m. Pearson's product moment correlations were used to assess the relationships between measures, and independent samples t tests were used to determine whether differences existed in sprint ability of those in the top and bottom quartiles for force at 100 ms, CMJ, and RSI. Significant negative moderate correlations were reported between force at 100 ms and 0-5 m and 5-10 m, significant moderate and large negative correlations between CMJ and all splits and significant large correlations between RSI and splits over 5 m. Force at 100 ms distinguished between performance levels from 0 to 5 m, CMJ from 10 to 20 m, and RSI from 20 to 30 m; faster subjects produced significantly higher force, JHs, and RSI scores. Three principal components explaining 86.1% of the variation in the data set were identified: sprint times and stretch shortening cycle capabilities (33.3%), time-specific force (29.9%), and absolute and relative strength (22.8%).

The Strength Characteristics of Elite and Subelite Female Gaelic Football Players.

Hughes, W, Healy, R, Lyons, M, Higginbotham, C, Lane, A, and Beattie, K. The strength characteristics of elite and subelite female Gaelic football players. J Strength Cond Res 38(6): 1072-1081, 2024-There is currently an underrepresentation of sports science research focused on the female athlete, specifically in the context of Gaelic football. The aims of this study are to (a) compare the strength characteristics of elite and subelite players and (b) establish normative-based values and percentile scores for the strength characteristics of female Gaelic football players. Ninety-two female Gaelic football players were recruited for this study and subsequently categorized as elite (intercounty n = 30, age; 25.1 ± 5.3 years, stature; 1.69 ± 0.06 m, mass; 69.5 ± 5.9 kg) or subelite (club n = 62, age; 25.4 ± 6.8 years, stature; 1.66 ± 0.06 m, mass; 65.1 ± 8.9 kg). The physical strength characteristics of the subjects were assessed through the isometric midthigh pull (IMTP), countermovement jump (CMJ), and 10-5 repeated jump test. Statistically significant differences were found in the physical strength characteristics between the groups with elite players demonstrating greater peak force (large effect), relative peak force (moderate effect), and reactive strength index (large effect). Statistically significant differences were also observed for key CMJ phase characteristics with elite players producing greater RSI mod (moderate effect), jump height (large effect), and propulsion peak power (large effect) than subelite players. This study demonstrated that there are moderate to large differences between playing standards with elite players displaying superior reactive-, explosive-, and maximal-strength than their subelite counterparts. The strength characteristics evaluated in this study may be used in conjunction with other performance indices to distinguish between elite and subelite playing standards in female Gaelic football players.

Combined effects of Rhodiola rosea and caffeine supplementation on aerobic endurance and muscle explosiveness: a synergistic approach.

This study examined the synergistic effects of combining Rhodiola rosea (RHO) and caffeine (CAF) supplementation on muscle endurance and explosiveness in SD rats and human subjects, encompassing individuals without prior exercise training experience and seasoned aerobic athletes. Male SD rats and healthy human volunteers were randomly divided into four groups: CAF, RHO, CAF + RHO, and a control group (CTR). Nutritional supplements were administered throughout the training period, and pre-and post-measurement data were collected. In both the rat model and human subjects, the RHO+CAF group demonstrated significantly greater effects compared to the use of RHO or CAF supplements individually. Rats in the RHO+CAF group demonstrated extended running and swimming times and an increase in erythropoietin (EPO) mRNA expression in comparison to the CTR. Blood parameters, such as serum EPO levels, were enhanced in the CAF + RHO group, while blood urea nitrogen (BUN) and lactate (LA) levels significantly decreased in both the RHO and CAF + RHO groups. Hepatic and muscle glycogen contents were also higher in these groups. The gene expression analysis in rats demonstrated an elevation in the mRNA levels of glucose transporter-4 (GLUT-4), peroxisome proliferator-activated receptor γ coactivator-1 alpha (PGC-1α), Monocarboxylate transporter 1 (MCT-1), and Heme Oxygenase-1 (HO-1) in both the RHO and RHO+CAF groups. For individuals without prior aerobic training experience, the RHO+CAF group showed significant improvements compared to the CTR group in maximal oxygen consumption (VO2max), 5 km run, countermovement jump (CMJ), standing long jump, and 30 m sprint. For individuals with years of aerobic training experience, the RHO+CAF group exhibited enhanced performance in the 5 km run, CMJ, and standing long jump compared to the CTR group. In conclusion, the continuous 30 days supplementation of RHO, combined with a single dose of CAF, demonstrated superior effects on muscle endurance and explosiveness in both animal and human studies when compared to the use of RHO or CAF individually.

Effects of Warm-Ups with Weighted Vests and Resistance Bands on Physical Fitness and Combat Ability of Kumite Karate Athletes.

The purpose of this study was to investigate whether a dynamic warm-up either with weighted vests (WVs) or with resistance bands (RBs) may enhance the physical fitness and combat ability of kumite karate athletes. Nine male athletes (age range from 16 to 30 years), participated in this study. Athletes followed three different warm-up programs in a randomized order: (a) with their body mass only (C), (b) with a WV of 10% load of their body mass and (c) with a wearable RB of 10% tension of their body mass. Following the warm-up, athletes performed the following tests: countermovement jump (CMJ), standing long jump (LJ), punch and kick reaction time, bench press throws, T-Half test and the kick frequency test. CMJ remained unaltered following the WV and RB warm-up compared to the C. Standing long jump increased significantly following the RB warm-up compared to the C (2.2 ± 1.7%, p = 0.011). Punch reaction time was significantly shortened following the RB warm-up compared to C (-7.3 ± 5.9%, p = 0.019). No changes were observed for kick reaction time, bench press throws or the T-Half test. The kick decrement index, measured from the kick frequency test, was significantly decreased following the RB warm-up compared to the C (33.1 ± 20.2%, p = 0.011). These results suggest that an RB warm-up may significantly enhance the physical fitness and combat ability in kumite karate athletes.

Changes in Body Composition and Physical Performance after a Six-Week International Tour in Young Chilean Female Tennis Players.

Junior tennis players travel a lot to play tennis tournaments; this causes them to spend a lot of time away from their homes and disrupts their training, which could reduce their performance and increase the risk of injury. The purpose of this study was to analyze the changes in physical performance and body composition after a six-week international tour in young Chilean female tennis players. Thirty young female tennis players (15.4 ± 0.6) participated in this study. Body weight, skinfolds, and perimeters were measured. Body fat percentage (BFP) and skeletal muscle mass (SMM) were calculated. For physical performance, 5 m sprint, the 505 with stationary start test (505 test), the pro-agility test, countermovement jump (CMJ), and medicine ball throw (MBT) were evaluated. The results show a significant increase in BFP and decrease in SMM (p < 0.01; d = -0.18 and 0.19, respectively). In terms of physical performance, 5 m sprint, the 505 test (p < 0.01; d = -0.95 and -0.95, respectively), CMJ, MBT, and HJ significantly decreased post-tour (p < 0.05; d = 0.96, 0.89 and 0.47, respectively). We conclude that, after a six-week international tour, there were changes in body composition and a significant decrease in 5 m sprint, the 505 test, CMJ, and MBT.

COMPOUND TRAINING: A STUDY ON THE INFLUENCE ON THE BOUNCING FORCE OF VOLLEYBALL PLAYERS WHEN THEY JUMP AND SPIKE THE BALL

Objective: This paper aims to investigate the impact of compound training (CT) on the jumping spike performance of volleyball players. Methods: Twenty athletes were randomly assigned to either the CT group or the resistance training (RT) group. After eight weeks of training, the results for in-situ jump and reach, run-up jump and reach, as well as squat jump (SJ), counter-movement jump (CMJ), and run-up jump measured using the Just Jump test system were compared between the two groups. Results: Prior to the experiment, there were no significant differences in any of the test parameters between the two groups ([Formula: see text]). Following the experiment, the one-repetition maximum (1RM) weighted deep squat result for the CT group was [Formula: see text][Formula: see text]kg, the in-situ jump and reach height was [Formula: see text][Formula: see text]m, and the run-up jump and reach height was [Formula: see text][Formula: see text]m, all with [Formula: see text] compared to pre-experiment values and the RT group. Additionally, the duration and height of flight of SJ in the CT group were [Formula: see text][Formula: see text]s and [Formula: see text][Formula: see text]cm, respectively; the duration and height of flight of CMJ were [Formula: see text][Formula: see text]s and [Formula: see text][Formula: see text]cm, respectively; the duration and height of flight of run-up jumps were [Formula: see text][Formula: see text]s and [Formula: see text][Formula: see text]cm, respectively. All of the above results were significantly higher than those before the experiment and those of the RT group ([Formula: see text]). Conclusion: The superior results observed in the CT group’s jumping tests suggest that the effects of CT on bouncing force are more pronounced, making it a viable approach for practical training.

Associations between biological maturation, physical performance, postural control, and mathematical achievement in youth soccer players.

This investigation explored relationships between biological maturation, physical and academic performance in young male soccer players. Thirty-eight players (age: 9.79 ± 1.21 years; body mass index (BMI): 20.4 ± 2.39 kg/m2; body fat: 16.8 ± 2.21%) participated. Measures of anthropometry used for body mass, body fat percentage (%BF), and BMI as well. Postural control, 15 m sprint, squat jumps and counter-movement jumps (SJ, CMJ), and T-half test for change-of-direction (CoD) were parameters of physical performance. The grade point average (GPA) of mathematics determined academic attainment. Moore's equations were used to estimate their maturity status (PHV). Biological maturation was highly correlated with most (not 15 m sprint) physical and academic performance parameters, especially CMJ (r = -0.812) and mathematics (r = -0.781). Academic performance showed the largest relations to the jumping performance (CMJ: r = 0.771; SJ: r = 0.723). In contrast, anthropometric and fatness parameters were not relevantly (r ≥ 0.5) correlated with any other parameters. The largest correlations were calculated for sitting height vs. SJ (r = -0.408), sitting height vs. postural control (r = -0.355), leg length vs. postural control (r = -0.339). As a result, it is essential to take biological maturation inconsideration while assessing the physical and academic achievement of young soccer players. In consequence, soccer coaches and physical education (PE) teachers should be cognizant of the impact of biological maturity on physical and academic performance to assist fair and equal opportunities for achievement in young players.

Influence of different verbal cue types on countermovement jump performance in youth female athletes

Although external (EXT) verbal cues have been shown to improve jump performance, limited research has been conducted in youth athletes. Therefore, the purpose of this study was to investigate how different EXT verbal cue types influenced countermovement jump (CMJ) performance in youth athletes. Ten young trained female athletes (16.80 ± 0.60 years) performed the CMJ using four different EXT verbal cues including external-distal (DIST), external-proximal (PROX), analogy (ANA) and holistic (HOL) as well as a neutral cue (CON). Jump height, reactive strength index modified (RSIMOD), countermovement depth, jump time and force-time measures from eccentric and concentric CMJ subphases were measured. No significant differences between cue types were found for RSIMOD. ANA resulted in significantly higher jump height compared to CON ( g = 0.37). PROX significantly increased jump time ( g = 0.60), concentric time ( g = 0.47) and braking time ( g = 0.52), as well as significantly decreasing eccentric braking mean force ( g = 0.43) and eccentric braking rate of force development ( g = 0.59) compared to CON. Countermovement depth significantly increased when using PROX ( g = 0.60), HOL ( g = 0.46) and ANA ( g = 0.51) compared to CON. These results suggest that compared to a neutral cue, EXT verbal cues result in similar CMJ performance in trained youth athletes. However, PROX verbal cues appear to result in reduced performance in many CMJ force-time measures.