Counter Movement Research Articles

Rectus Femoris Muscle Composition: Association with Sports Performance and Playing Position in Female Soccer Players

Abstract Background Quadriceps muscle plays a relevant role in soccer as its function is determinant for sprinting, jumping and striking the ball. Although ultrasound demonstrated to be useful in risk of injury prevention and monitoring post-injury rehabilitation, no studies analyzed the ultrasound muscle histology with sports performance tests. We aimed to analyze the correlation between ultrasound findings related to rectus femoris morphology and composition with sports performance indicators and to analyze sociodemographic, sports performance and ultrasound differences according to playing position. Methods An observational study was conducted at the CFF OLYMPIA soccer club (Madrid, Spain). Twenty-two semi-professional female soccer players were enrolled in this study. Sociodemographic data, bilateral ultrasound measurements of the rectus femoris muscle and sports performance tests (Counter Movement Jump -CMJ-, The Sprint Repeat Ability -SRA-, and one Repetition Maximum -1RM-) were collected. Results No correlations between ultrasound imaging and sports performance indicators were found. Significant correlations between cross-sectional area and perimeter with age (p<0.05) and fatty infiltration with body mass index and tight perimeter (p<0.05) were seen. No muscle ultrasound morphology or quality differences were found between the playing positions (p>0.05). Finally, most of the functional tests showed no between-position differences (except SRA between goalkeepers and attackers). Conclusion Although muscle morphology and quality are associated with demographic features, US should not be used as a predictor of sports performance in female football players since no association between US and sports performance were observed. Similar US and functional test scores were obtained among the different playing positions.

The development and evaluation of a fully automated markerless motion capture workflow

This study presented a fully automated deep learning based markerless motion capture workflow and evaluated its performance against marker-based motion capture during overground running, walking and counter movement jumping. Multi-view high speed (200 Hz) image data were collected concurrently with marker-based motion capture (criterion data), permitting a direct comparison between methods. Lower limb kinematic data for 15 participants were computed using 2D pose estimation, our 3D fusion process and OpenSim based inverse kinematics modelling. Results demonstrated high levels of agreement for lower limb joint angles, with mean differences ranging “0.1° − 10.5° for hip (3 DoF) joint rotations, and 0.7° − 3.9° for knee (1 DoF) and ankle (2 DoF) rotations. These differences generally fall within the documented uncertainties of marker-based motion capture, suggesting that our markerless approach could be used for appropriate biomechanics applications. We used an open-source, modular and customisable workflow, allowing for integration with other popular biomechanics tools such as OpenSim. By developing open-source tools, we hope to facilitate the democratisation of markerless motion capture technology and encourage the transparent development of markerless methods. This presents exciting opportunities for biomechanics researchers and practitioners to capture large amounts of high quality, ecologically valid data both in the laboratory and in the wild.

Effects of two explosive strength circuits on power, speed and agility in U16 football players

The purpose of study was to examine the effect of two circuits, which consists in specific plyometric drills and football-specific sprints combined with technical elements (crosses and finishing from crosses, feint, dribble and shoot), on the performance level related to explosive strength, power, speed and agility in U-16 football players. Forty U16 junior football players were selected to participate in this study (20 in the experimental group and 20 in the control group). For the experimental group was applied a weekly training programme (the experimental intervention), which consisted in two specific explosive strength circuits with sprints on four and three pitch zones. The tests consisted of vertical jumps – squat jump, counter movement jump and 15” Bosco Repeated Jump Test, drop jump, 10 m, 20 m and 30 m linear sprints and the Illinois Agility Test. The experimental group showed performance improvements (p < 0.05) in all explosive strength and power tests, while the increases of the control group were not statistically significant. At speed and agility tests (10 m, 20 m and 30 m sprints and the Illinois test), the experimental group showed significant performance improvements for the 10 m, 20 m and 30 m sprints, and for Illinois Agility Test (p < 0.05). The observed differences between the experimental and the control group (at initial and final testing) were discussed, and recommendations regarding the effectiveness of the intervention programme were highlighted.

INFLUENCE OF BODY COMPOSITION ON BASIC MOTOR ABILITIES IN HANDBALL PLAYERS

The aim of this study was to investigate the influence of body composition on motor abilities in handball players. The sample involved 16 male handball players aged 15-20. Body composition variables included body mass (BM), the body mass index (BMI), percentage of body fat (PBF) and percentage of muscle mass (PMM). For speed assessment, the 20m sprint test was used. The T-test, Slalom test and Zig-Zag test were used to estimate agility, while the squat jump (SJ), counter movement jump (CMJ) and counter movement jump with arm swing (CMJa) were used to assess the muscle strength of the lower limbs. Linear regression analysis was used to determine the influence of body composition variables on basic motor abilities. Negative, statistically significant correlations were observed between BMI, PBF, sprint speed and agility (r = 0,52 – 0,66, R2 = 0,27 - 0,44, p < 0,05). Muscle mass contributed to better performance on speed and agility tests (-0,55 < r < -0,67, R2 = 0,31 - 0,45, p < 0,05). There were no significant relationships between BM and motor abilities, as well as between the muscle strength and body composition variables. These findings indicate that obesity contributes to slower linear and multidirectional movement, while muscle mass makes handball players faster. More research is needed in order to determine the influence of body composition on muscle strength, and the influence of body mass on specific handball movements.

The role of school physical education on adolescents' fitness levels during the pandemic period from COVID-19: An observational study of the Italian scientific high school-section sport and physical activity.

ObjectivesIn Italy, in 2013, a new school curriculum with a sport character was established in high schools, called Sports High School (SHS). The aims of this study were: (1) to assess the fitness levels of SHS students who, respecting all the safety rules to limit the spread of COVID-19, practiced physical education (PE) at school with continuity for almost all of 2021, and to compare them with Traditional High School (THS) students; (2) to evaluate as the SHS may have influenced the fitness levels in adolescents.MethodsThis is a case-control study in which thirty participants were enrolled (SHS: n = 15; THS: n = 15). To assess the fitness levels, the following tests were administered: the Static Baropodometric and Stabilometric Analyses, the Counter Movement Jump (CMJ), and the Handgrip test. All these tests were administered when the non-pharmaceutical interventions (NPIs) for COVID-19 allowed the resumption of PE lessons (T0) and 2 months after their resumption (T1).ResultsUnpaired t-test between SHS (T0) vs. THS (T0) showed significant differences between: Handgrip test Dx and Handgrip test Sx (both p < 0.001), Surface Sx foot and Surface Dx foot (both p < 0.05), and CMJ (p < 0.001). These results were also confirmed in T1. The performance analysis between T0 and T1 of both SHS and THS showed improvements in SHS: Handgrip test Dx (p < 0.05; d = 0.57), Handgrip test Sx (p < 0.01; d = 0.87), and CMJ (p < 0.05; d = 0.59). Pearson's analysis of the results of the tests showed significant strong correlations between: Handgrip test Dx and Handgrip test Sx (R = 0.959; p < 0.001), Handgrip test Dx and CMJ (R = 0.881; p < 0.001), Handgrip test Sx and CMJ (R = 0.893; p < 0.001). The same analysis showed significant but moderate correlations between: Surface foot Sx and CMJ (R = 0.489; p < 0.01), Surface foot Sx and y-mean (R = 0.485; p < 0.01), Surface foot Dx and CMJ (R = 0.444; p < 0.05).ConclusionsThis study is in agreement with the literature showing that the quarantine period and the NPIs for COVID-19 caused a decrease in fitness levels in adolescents. Our results showed that students of SHS recorded higher strength performance both in the Handgrip test and in the CMJ.

Deaf and non-deaf basketball and volleyball players' multi-faceted difference on repeated counter movement jump performances: Height, force and acceleration.

The aim of this study was to compare the performances of Repetitive Counter Movement Jumping (basketball/volleyball) of deaf/non-deaf athletes. Athletes playing in the Turkish Deaf Basketball and Volleyball national teams and in Basketball and Volleyball First Leagues participated in the study. The study group consisted of 51 male athletes, including deaf basketball (n = 11; age: 26.18 ± 4.79 years), deaf volleyball (n = 12, age: 26.33 ± 4.27 years), non-deaf basketball (n = 14, age: 26.93 ± 4.87 years), and non-deaf volleyball (n = 14, age: 24.93 ± 5.10 years) players. As a result of the test, Jump Height from Take Off Velocity, Jump Height from Take Off Velocity, Jump Height from Flight Time, Counter Movement Acceleration, Push Off Acceleration, Average Velocity, Average Power, and Average Force were analyzed. Differences in the jump performances among the groups (deaf basketball and volleyball, non-deaf basketball, and volleyball) were tested by one-way analyses of variance (ANOVA) with Tukey's post-hoc follow-up testing when necessary for jump test. As a result, this is the first study to investigate the number of jumps and jump height, the force produced, acceleration at the time of jump, and jump velocity during 30 s in deaf and non-deaf basketball and volleyball players within the scope of individual Repeated Counter Movement Jump test. Based on the biomechanical changes according to our results, our findings show a greater decrease in the number of jumps and jump heights, the force produced, the acceleration at the moment of the jump and the jump velocity in all athletes, especially those that affect the deaf.

SEX-DIFFERENCES IN COUNTER MOVEMENT JUMP KINETICS AND KINEMATICS FOLLOWING 10-WEEK MARINE OFFICER CANDIDATES SCHOOL

The Counter Movement Jump (CMJ) is a field expedient test to evaluate kinetics and kinematics relating to readiness, and injury risk. There is a greater incidence of injuries in women during military training and understanding key measures within the CMJ between sexes may be useful in determining injury/performance differences. PURPOSE: To evaluate sex differences in performance, kinetic and kinematic variables for the CMJ in Marine Officer Candidates (MOC) pre and post Officer Candidates School (OCS). METHODS: 375 MOCs (women n=72, 25±3 y, 65.9±7.1 kg, 164.9±5.7 cm; men n=303, 25±3 y, 81.3±9.4 kg, 177.5±6.9 cm) performed three maximal CMJs, 15 second rest between CMJs, on Hawkin Dynamics force plate (FP) and DARI marker less motion capture (mMoCap) pre and post 10-weeks of OCS, a rigorous graded physical, leadership and academic training pipeline for incoming Marine Officers. Three CMJs were averaged to one jump, and right and left limbs were averaged for mMoCAP. Separate 2-way mixed measures ANOVAs (Time*Sex) were conducted on each CMJ dependent variable 1) FP: avg. propulsive force (APF), avg. braking force (ABF), jump height (JH) 2) mMoCap: loading hip flexion (LHF), loading knee flexion (LKF), loading ankle flexion (LAF). RESULTS: There was a significant interaction effect on JH (p=<.001, np2=.04) and APF (p<.001, np2=.07). Simple main effects of time showed that JH declined differently between women (.29±.05 to .28±.04 m, p<.001, np2=.16) and men (.40±.06 to .37±.06 m, p<.001, np2=.04), and APF improved in women (1053±144 to 1063±140 N, p=.242, np2=.02) but declined in men (1404±201 to 1361±177 N, p<.001, np2=.22). ABF displayed a significant decline over time (p<.001, np2=.04) and men performed better than women (p<.001, np2=.25). There were no significant interactions or main effect of sex for mMoCap, but LHF (p<.001, np2=.12), LKF (p<.001, np2=.12) and LAF (p<.001, np2=.03) decreased significantly over time. CONCLUSION: Kinematics decreased for men and women, while kinetics were less consistent from this trend in women. Although stiffer CMJ loading flexions in all joints, JH and ABF declined for both men and women, women slightly gained propulsive force, thus contributing to efficiencies in the CMJ protected and improved after OCS for women. Funded by the Office of Naval Research: N00014-20-C-2020

Sex Differences In Relative Force And Power Development During A Countermovement Jump

Research has shown that the measurement of countermovement jumps may relate to sport performance and injury. Certain measurements of force production and power output can additionally inform the athlete and coaches of deficiencies in strength and velocity. These measurements can help inform players and coaches of specific training modalities that may lead to improvements in these measurements. Among elite level athletes, biological males often produce more force and power during a counter movement jump, than biological females due to differences in lean body mass and overall body fat percentage. PURPOSE: The purpose of this study was to compare normalization methods of force and power production during a counter movement jump in college basketball players. METHODS: 15 Division 1 basketball players participated in the study (7 females, 20.8 ± 2.2 yrs, 1.79 ± 0.09 m., 84.7 ± 12.9 kg; 8 males, 21.5 ± 1.2 yrs, 1.94 ± 0.09 m., 91.5 ± 11.3 kg). Participants performed a warmup consisting of 5 minutes of stationary cycling and dynamic stretching. Participants then performed three countermovement jumps on two force plates (Bertec Inc.) while data was collected and analyzed using Noraxon MR:16 software. Body composition was assessed using air displacement plethysmography (Bod Pod, Cosmed). RESULTS: Biological males (11.5 ± 4.4 %) had reduced body fat percentage compared to biological females (25.6 ± 4.4%, p < 0.001). Biological males jumped 11.8 cm higher (46.2 ± 4.1 cm) than biological females (34.3 ± 71 cm, p = 0.001). When normalized to body mass, concentric power (33%, p < 0.001) and concentric force (11%, p = 0.03) were higher in biological males compared to biological females. When normalized to lean body mass, there were no significant differences in concentric power or concentric force between males and females. When concentric peak force was normalized to only lean body mass, biological females showed a nonsignificant increase of 6% (p = 0.19) compared to biological males. CONCLUSION: Jumping power and force differences were reduced between biological males and females when normalized to lean body mass, likely due to the increase in body fat percentage in biological females. These data suggest that care should be taken when considering methods of normalization for gender comparisons of jumping power and force.

Heart Rate Variability And Its Association With The Autonomic Response During Jump Performance In Female Soccer Players

Heart rate variability (HRV) has been established as a valid index for examining cardiac autonomic modulation. The eccentric utilization ratio (EUR) is a novel index examining the stretch shortening cycle and is calculated by dividing the jump height of both the squat jump and counter movement jump. The reactive strength index (RSI) is another assessment examining the autonomic response of a muscle contraction when performing a drop jump test. Currently, there remains a paucity of inquiry around the association between heightened cardiac vagal modulation and improvement in jump performance when utilizing the stretch shortening cycle. PURPOSE: To examine the association between cardiac vagal modulation using rMSSD and jump performance assessments utilizing the stretch shortening cycle in healthy female collegiate soccer players. METHODS: Seventeen healthy female collegiate soccer players with an age of (mean ± SD) 18.5 ± 0.75 yr, a weight of 57.3 ± 9.2 kg, a height of 165.4 ± 7.2 cm, and a body fat % of 23.2 ± 7.4 volunteered as participants. HRV was analyzed in the supine position after a 10-min stabilization period. R-R intervals were recorded over 60-seconds using the Polar Team Pro® chest strap and were exported into Kubios HRV 3.4 (University of Kuopio, Kuopio, Finland) for HRV analyses. Each participant performed three separate squat jumps, counter movement jumps and drop jumps with their hands placed on their hips. Jump performance was assessed using a force plate (Hawkin Dynamics Force Plate, ME, USA). The highest jump was included for each analysis. Normality of each data set was examined using a Shapiro-Wilk’s test for normality (p > 0.05). Linear regression (R2) was utilized to examine the association between rMSSD and both EUR and RSI. This study was approved by and followed the recommendation of the Research Ethics Review board at Langara College. RESULTS: No significant associations were observed between rMSSD and both EUR (R2 = 0.004, p = 0.74) and RSI (R2 = 0.001, p = 0.87). CONCLUSION: HRV may not be suitable for examining the autonomic response when utilizing the stretch shortening cycle during jump performance testing. This investigation was funded by the Langara College ARC-1 grant.

Influence of the sport specific training background on the symmetry of the single legged vertical counter movement jump among female ballet dancers and volleyball players

IntroductionVertical jumps are the key components of performance in the classical ballet and volleyball. Asymmetry of performance between the lower extremities is a potential risk factor for injury. PurposeThe purpose of this study was to analyse the symmetry of the unilateral vertical countermovement jump (CMJ) in a group of female ballet dancers and in a group of female college volleyball players. MethodsWe tested the CMJ with the dominant and nondominant leg and the bilateral CMJ among 15 female ballet dancers and 15 female volleyball players aged 18–24 years. Ground reaction forces were recorded with the force plate and five variables were analysed - jump height, power, energy, and time to flight and time to maximum force during landing. Results2 × 2 repeated measures of ANOVA indicates that type of sport is influencing some of the single leg CMJ variables (energy used and time to maximal force in landing), there was a significant asymmetry between dominant and non-dominant leg in some of the vertical CMJ variables (CMJ height, energy used and the average power was marginally significant). The interaction between the type of sport and leg dominance however was not significant for all of the analysed CMJ variables indicating no difference in asymmetry between the dominant and non-dominant leg in the two investigated sports. The results expressed in the percentage differences between both legs that is widely used in the scientific literature showed that ballet dancers exhibited more symmetrical CMJ height, power, and energy compared to volleyball players. The average percent difference in CMJ height between the dominant and non-dominant leg was 4.26 (10.60) % and 13.36 (14.72) %, respectively. On average, volleyball players jumped slightly higher at the bilateral CMJ (p < 0.001). ConclusionSport-specific training background could explain the observed contralateral deficit differences between two sport groups. The elements of ballet training could be introduced into the volleyball training to overcome observed this contralateral deficit.

Effects of plyometric training on softer vs. Harder surfaces on jump-related performance in rugby sevens players.

This study aimed to compare jump-related performance after plyometric training on harder vs. softer surfaces in rugby sevens players. Fourteen players were randomly assigned to the harder surface group (H-G, n = 7) and softer surface group (S-G, n = 7). Three times per week, in the morning, the players performed plyometric training on different surfaces and strength training. Before and after the 4-week intervention period, squat jump (SJ), countermovement jump (CMJ), and CMJ with arms (CMJA) tests were performed to measure vertical jump displacement (d), rate of force development (r), and power (p). The main results indicated a significant improvement in S-G for CMJd (∆% = +8.2%; p = 0.029; ES = 0.59) and for CMJAp (∆% = +8.7%; p = 0.035; ES = 0.44). These improvements were significant compared to H-G for CMJAd (F1,12 = 8.50; p = 0.013; = 0.41; ES = 0.83) and CMJAp (F1,12 = 7.69; p = 0.017; = 0.39; ES = 0.79). This study reveals that performance related to the counter movement jump with arms on softer surfaces after 4-week plyometric training improved vertical jump displacement and lower body power in rugby sevens players.

The Influence on Post-Activation Potentiation Exerted by Different Degrees of Blood Flow Restriction and Multi-Levels of Activation Intensity.

(1) Background: To explore the influence on post-activation potentiation (PAP) when combining different degrees of blood flow restriction (BFR) with multi-levels of resistance training intensity of activation. (2) Purpose: To provide competitive athletes with a more efficient and feasible warm-up program. (3) Study Design: The same batch of subjects performed the vertical jump test of the warm-up procedure under different conditions, one traditional and six BFR procedures. (4) Methods: Participants performed seven counter movement jump (CMJ) tests in random order, including 90% one repetition maximum (1RM) without BFR (CON), and three levels of BFR (30%, 50%, 70%) combined with (30% and 50% 1RM) (BFR-30-30, BFR-30-50, BFR-50-30, BFR-50-50, BFR-70-30 and BFR-70-50). Jump height (H), mean power output (P), peak vertical ground reaction force (vGRF), and the mean rate of force development (RFD) were recorded and measured. (5) Results: Significantly increasing results were observed in: jump height: CON (8 min), BFR-30-30 (0, 4 min), BFR-30-50 (4, 8 min), BFR-50-30 (8 min), BFR-50-50 (4, 8 min), BFR-70-30 (8 min), (p < 0.05); and power output: CON (8 min), BFR-30-30 (0, 4 min), BFR-30-50 (4 min), BFR-50-30 (8 min), BFR-50-50 (4, 8 min) (p < 0.05); vGRF: CON (8 min), BFR-30-30 (0, 4 min), BFR-30-50 (4, 8 min), BFR-50-30 (4 min), BFR-50-50 (4, 8 min) (p < 0.05); RFD: CON (8 min), BFR-30-30 (0, 4 min), BFR-30-50 (4 min), BFR-50-30 (4 min), BFR-50-50 (4 min) (p < 0.05). (5) Conclusions: low to moderate degrees of BFR procedures produced a similar PAP to traditional activation. Additionally, BFR-30-30, BFR-30-50, and BFR-50-50 were longer at PAP duration in comparison with CON.

Continuous time series analysis on the effects of induced running fatigue on leg symmetry using kinematics and kinetic variables: Implications for knee joint injury during a countermovement jump.

This study investigates the symmetry change in joint angle and joint moment of knee joints following a Running-Induced Fatigue counter movement Jump. Twelve amateur runners volunteered to participate in the study. A prolonged running protocol was used to induce fatigue. Joint angle and moment were recorded during the push and flexion phase of the CMJ before and immediately after fatigue. Borg scale (RPE>17) and real-time heart rate monitoring (HR>90%HRmax) were used to confirm running fatigue. Symmetry function (SF) was used to assess the symmetry of the knee Angle and moment variation parameters over the entire push-off and landing phases based on time series analysis. Paired sample t-test was used to examine changes in SF before and after acute fatigue. The Angle and moment of the knee are asymmetrical in all planes (SF > 0.05), with SF ranging from 5 to 130% in angle and 5–110% in moment. There was a significant increase in knee joint angle asymmetry in the horizontal plane during the push-off and landing stage following the prolonged - Running Protocol implementation. These increases in asymmetry are mainly caused by excessive external rotation of the dominant knee joint. These findings indicate that fatigue-induced changes during CMJ may progress knee movement pattern asymmetry in the horizontal plane.

A randomized open-labeled study to examine the effects of creatine monohydrate and combined training on jump and scoring performance in young basketball players.

ABSTRACTBackgroundCreatine monohydrate (CrM) supplementation has been shown to be an effective and safe nutritional supplement to improve performance; however, the impact of CrM supplementation in young basketball players is less clear. This study evaluated the effects of CrM supplementation during a strength and conditioning training (SCT) program on lower-limb strength parameters and performance in under-16 (U16) basketball players.MethodsTwenty-three male U16 basketball players participated in this study (14.3 ± 0.4 years; BMI: 20.7 ± 2.2 kg∙m−2). The players were randomly assigned to either a CrM group (n = 12) that ingested 0.1 g·kg−1·day−1 of CrM or to a non-supplemented control group (n = 11, CON). The athletes participated in an 8-week SCT program consisting of two lower-limb resistance-training sessions and two plyometric sessions per week. Squat jump (SJ), drop jump (DP), countermovement jump (CMJ), and Abalakov (ABK) jump power tests as well as basketball performance (points and minutes per game) were measured before, during and/or after the intervention. Data were analyzed using a general linear model with repeated measures with independent Student’s t-test pairwise comparisons.ResultsThe results (95% confidence interval for mean change from baseline) show that there were significant differences for all variables for CrM and CON, respectively: SJ (cm): 2.6 – 6.4, P < 0.01 and 2.2–5.1 P < 0.01; DJ (cm): 2.5–5.6, P < 0.01, and 1.8–4.4, P < 0.01; CMJ (cm): 0.3–0.8, P < 0.01, and 0.2–0.5, P < 0.01; ABK (cm): 2.8–5.5, P < 0.01 and 0.7–2.6, P = 0.003. A significant group x time interaction (p = 0.003, ηp2 = 0.342) was observed in ABK performance. No significant group x time effects were seen in squat jump (p = 0.449, ηp2 = 0.028), drop jump (p = 0.143, ηp2 = 0.099), or counter movement jump (p = 0.304, ηp2 = 0.05). A significant interaction effect was also observed in points per game (p = 0.049, ηp2 = 0.149), while a non-significant but medium effect was seen in minutes per game (p = 0.166, ηp2 = 0.094).ConclusionsCrM supplementation in conjunction with resistance and plyometric training increased the lower-limb ABK power and scoring performance in U16 basketball players.

Effects of Different Levels of Weightlifting Training on Bone Mineral Density in a Group of Adolescents

The aim of the current study was to evaluate the effects of different levels of weightlifting training on bone mineral density (BMD) at different body sites (whole body (WB), lumbar spine (LS), femoral neck (FN), upper limbs (UL) and lower limbs (LL)) in a group of adolescents. Three groups of pubertal boys aged 13-15 years were recruited, including a control group (which included 13 untrained adolescents), a moderately trained group (which included 13 non-elite weightlifters, with four sessions of 2 hours per week) and a highly trained group (which included 13 elite weightlifters, with eight sessions of 2 hours per week). The three groups were paired for age and maturation index (using Tanner stages). Body composition, bone mineral content (BMC) and BMD were evaluated by dual-energy X ray absorptiometry (DXA). Physical performance variables (including weightlifting specific exercises, counter movement jump and squat jump) were measured using validated methods. Results showed that the values of BMD and physical performance variables were greater in the group of elite weightlifters compared to the group of non-elite weightlifters and the control group. In addition, the values of BMD and physical performance variables were higher in the group of the non-elite weightlifters compared to those of the control group. After adjusting for lean mass and squat jump, lumbar spine BMD, FN BMD, UL BMD and LL BMD remained significantly higher in the elite weightlifters’ group compared to the two other groups. In conclusion, the current study suggests that elite adolescent weightlifters have greater bone health parameters compared to moderately-trained adolescent weightlifters and untrained adolescents.

Moving up the stream beyond resistance to counter move

In the following paper, we aim for an extended understanding of the most crucial phenomena itself, the generation of meaning in the interaction with—what we describe as reality. The cultural psychological core principles are re-introduced and connected to a new more holistic construction, elaborating the generation of new meaning. In the same context, new terminology will be introduced, crucial for the understanding of the from phenomenology generated perspective toward cognitive processes and their interrelation with the everyday life. Borders not only as separator but also as deep connector of meaning are for this purpose explored and reintroduced. A procedure that led to central understandings that go far beyond the simple definitions accessible in dictionaries. As significant organic metaphor the river and the meadow (Towards a wholistic model of identity: Why not a meadow? Integrative Psychological and Behavioral Science, 55(1), 112–127. https://doi.org/10.1007/s12124-020-09588-3) will be used and extended by the rabbit hole, a triggered process extending the imagination of individuals by the central counter movement against streams and Gegenstände.

Differences in Force-Velocity Profiles During Countermovement Jump and Flywheel Squats and Associations With a Different Change of Direction Tests in Elite Karatekas.

The force-velocity (F-v) relationship has been proposed as a biomechanical characteristic to comprehensively evaluate neuromuscular capabilities within different tasks such as vertical jumping, sprinting and bench pressing. F-v relationship during flywheel (FW) squats was already validated, however, it was never compared to F-v profile of vertical jumps or associated with change of direction (CoD) performance. The aims of our study were (1) to compare F-v profiles measured during counter movement jumps (CMJs) and FW squats, (2) to determine correlations of F-v mechanical capacities with different CoD tests, (3) to investigate the portion of explained variance in CoD tests with the F-v outcome measures. A cross-sectional study was conducted on 39 elite karatekas. They performed CMJs and FW squats using progressive loads to calculate F-v profile outcome variables and different CoD tests (CoD at 90°, CoD at 180°, t-test, short karate specific test (KST) and long KST). Our results showed significantly higher values in all F-v outcome variables (F0—theoretical maximal force, V0—maximal unloaded velocity, Pmax—maximal power output, F-vslope—the slope of F-v relationship) calculated from CMJs compared to FW squats (all p < 0.01). Significant positive moderate correlations between the tasks were found for F0 and Pmax (r = 0.323–0.378, p = 0.018–0.045). In comparison to F-v outcome variables obtained in FW squats, higher correlations were found between F-v outcome variables calculated from CMJs and CoD tests. The only significant correlation in F-v outcome variables calculated from FW squats was found between Pmax and short KST time. For all CoD tests, only one F-v predictor was included; more specifically—CMJ-F0 for CoD 90°, CoD 180° and t-test, and FW-Pmax for short KST performance. To conclude, our results showed that F-v relationship between CMJs and FW squats differed significantly and cannot be used interchangeably for F-v profiling. Moreover, we confirmed that high force and power production is important for the successful performance of general and karate specific CoD tasks.

Low-Load Blood Flow Restriction Squat as Conditioning Activity Within a Contrast Training Sequence in High-Level Preadolescent Trampoline Gymnasts.

To investigate the effects of implementing low-load blood flow restriction exercises (LL-BFRE) instead of high-load exercises (HL-RE) in a contrast training program on strength and power performance of high-level young gymnasts. Fifteen high-level pre-pubescent trampoline gymnasts (national level, Tanner Stage II, intermediate experience in strength training) were divided into two groups to complete the same structure of a ten-week contrast strength training program differing only in the configuration of the first resistance exercise of the contrast sequence. The LL-BFRE group (n = 7, four girls, 13.9 ± 0.4 y) performed the first resistance exercise of the contrast with LL-BFRE (20%–30% 1RM, perceived pressure of 7 on a scale from 0 to 10). The HL-RE group (n = 8, four girls, 13.8 ± 0.5 y) trained the first resistance exercise of the contrast sequence with moderate-to-high load (60%–85% 1RM). Before and after the training period, isometric mid-thigh pull (IMTP), squat jump (SJ), counter movement jump (CMJ), and drop-jump (DJ) were performed to evaluate the effect of the intervention on strength and power capacities as primary outcomes. Changes in participants’ anthropometric measures, muscle mass, left and right thigh girth, IMTP relative to bodyweight (IMTP-R), eccentric utilization ratio (EUR), and reactive strength index (RSI) were assessed as secondary outcomes. There was no significant interaction (p > 0.05) between group x time in any power and strength outcome, although SJ and EUR showed a trend to significant interaction (p = 0.06 and p = 0.065, respectively). There was an overall effect of time (p < 0.05) in all power and strength variables (CMJ, SJ, EUR, DJ, RSI, IMTP, and IMTP-R). There was a significant interaction in muscle mass (MM) [β = 0.57 kg, 95% CI = (0.15; 0.98), t13 = 2.67, p = 0.019], revealing that participants in LL-BFRE increased their muscle mass (6.6 ± 3.1%) compared to HL-RE (3.6 ± 2.0%). Anthropometric variables did not present any group or interaction effect. However, there was a time effect (p < 0.05). Implementing LL-BFRE in place of HL-RE as a conditioning activity in a contrast training sequence might be equally effective in improving lower-body strength and power in preadolescent trampoline gymnasts.

Evolution of anthropometric and physical performance characteristics of international male cricketers from 2014 to 2020 in a World Cup winning nation

The aim of the study was to firstly present a comprehensive physical profile of international cricketers in a World Cup winning cricket nation. Secondly, to describe changes in physical profiles across seven years. Fifty-two senior international cricketers’ physical profiles were retrospectively analysed across seven years. Using linear mixed-modelling, changes in stature, body mass, sum-of-8 skinfolds, sprinting time (10 and 40 m), run-2 time, counter movement jump (CMJ), push and pull strength capacity and the Yo-Yo intermittent recovery test level-1 (Yo-Yo-IR1) were analysed during a seven-year period. There were no significant changes in body mass ( p = .63) or stature ( p = .99) during this time. However, there was a significant ( p &lt; .001) mean decrease of ∼14 mm in the sum-of-8 skinfolds. Distance covered in the Yo-Yo-IR1 also showed a significant ( p = .002) effect of years, with a mean increase of 459 m in 2017 when compared with 2014. A significantly ( p = .01) more balanced push-to-pull strength capacity ratio was also evident across years as a result of a significant ( p &lt; .001) increase in pull strength capacity. Significant ( p &lt; .05) fluctuations in CMJ, sprint and run-2 time were seen, with no obvious trends. International cricketers within our study have gone through a notable physical transformation that has likely resulted in an increase in lean mass and aerobic capacity. The change across time to a more balanced push-to-pull strength capacity may be beneficial for injury prevention.

The Influence of Maximum Strength Performance in Seated Calf Raises on Counter Movement Jump and Squat Jump in Elite Junior Basketball Players

In basketball high intensity jumping and sprinting performance is of high importance. There seems to be a relationship between maximal strength (MSt) and jumping performance in general, but influence of MSt in the plantar flexors and jumping performance seems not to be investigated very well. Thus, the aim of this study was to investigate the influence of MSt in the plantar flexors on jumping performance. 37 young elite basketball players were included (age: 13.9±1.8 years; weight: 66.4±16.8 kg; height: 179.21±13.24 cm) and countermovement jump (CMJ) and squat jump (SJ) height as well as unilateral and bilateral maximal isometric contraction in the plantar flexors with bended knee joint were assessed. Pearson correlations were calculated for MSt and jumping performance and Bland-Altman Analysis was performed to determine the level of variance between bilateral MSt assessment and cumulated MSt value of unilateral measurements. This study shows a moderate influence of isometric MSt in the calf muscle on jumping performance, so it seems beneficial to include the training of the plantar flexors in the training routine of basketball players. When determining MSt, the bilateral force deficit must be considered, even though there was no influence on determined correlations.