Squat Jump Research Articles

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.

Does Deep Squat Quality Affect the Propulsion of Baseball Throwing?

This study investigates the influence of the quality of the "deep squat" movement, adapted from the Functional Movement Screen (FMS) system, on the lower extremity movement pattern during baseball throwing, and its potential impact on throwing performance and propulsion efficiency. Twenty-two baseball players were recruited and categorized into two groups: 13 in the high-score squat group (HSS) and 9 in the low-score squat group (LSS), based on their deep squat screening results. This research explored disparities in ball velocity, propulsion efficiency, propulsion ground reaction force (GRF) characteristics, and throwing kinematics between these two groups. The findings revealed no significant difference in ball velocity between the groups. However, the LSS group demonstrated a lower propulsion GRF efficiency (p < 0.030, ES = 0.46), along with a higher vertical peak GRF (p < 0.002, ES = 0.66). In the pivot leg, the HSS group exhibited significantly lower impulse forces in the Impulse Fresultant (p < 0.035, ES = 0.45), throwing direction (p < 0.049, ES = 0.42), and vertical direction (p < 0.048, ES = 0.42). Additionally, the contribution to the ball velocity of the pivot leg was significantly greater in the HSS group, along with significantly better efficiency in Impulse Fresultant (p < 0.035, ES = 0.45), throwing direction (p < 0.053, ES = 0.41), and vertical direction (p < 0.032, ES = 0.46). In the leading leg, the HSS group demonstrated significantly lower impulse forces in the Impulse Fresultant (p < 0.001, ES = 0.69), throwing direction (p < 0.007, ES = 0.58), and vertical direction (p < 0.001, ES = 0.70). Moreover, the contribution to the ball velocity of the leading leg was significantly greater in the HSS group, accompanied by significantly better efficiency in Impulse Fresultant (p < 0.003, ES = 0.63), throwing direction (p < 0.005, ES = 0.60), and vertical direction (p < 0.021, ES = 0.49). In conclusion, this study suggests that squat screening is a valuable tool for assessing propulsion efficiency. Coaches and trainers should be mindful of players with low squat quality but high throwing performance, as they may face increased impact and injury risks in the future.

Development of an Abbreviated Model for Predicting Functional Movement Screen Score Within Tactical Populations.

Thompson, MB, Johnson, QR, Lindsay, KG, and Dawes, JJ. Development of an abbreviated model for predicting functional movement screen score within tactical populations. J Strength Cond Res 38(3): 607-611, 2024-The Functional Movement Screen (FMS) is a tool commonly used to identify compensations when performing 7 specific movement patterns. Timely administration of the full FMS is largely dependent on the practitioner's familiarity and experience with the screening battery. When working in populations that are time-poor (i.e., tactical professionals), administration of the full movement pattern battery is not always feasible. The purpose of this study was to determine which, if any, combination of movement patterns that comprise the FMS could be used to predict total score on this screen among first responders. Functional Movement Screen scores for 99 male subjects (mean ± SD; age: 37.55 ± 9.83 years; height: 180.38 ± 6.59 cm; and body mass: 97.87 ± 15.32 kg) and 9 female subjects (age: 33.22 ± 3.99 years; height: 172.11 ± 8.19 cm; and body mass: 83.99 ± 14.09 kg) from a single law enforcement and fire agency were used for this analysis. Subjects performed the full FMS, which consisted of the following movement patterns: deep squat (DS), hurdle step (HS), in-line lunge (ILL), shoulder mobility (SM), active straight leg raise (ASLR), trunk stability push-up (PU), and rotary stability (RS). A stepwise regression was used to determine the best predictors of the FMS 7-pattern model based on the model's R2. Cronbach's alpha and Guttman's lambda-2 were used to determine the reliability of the proposed models. The regression indicated that a 4-pattern model consisting of DS, ILL, SM, and PU was sufficient to predict approximately 84% of the full model (adjusted R2 = 0.84, p ≤ 0.001). This 4-pattern model was shown to be reliable with the 7-pattern model (α = 0.93, λ = 0.93). Using this modified version of the FMS may allow practitioners working in tactical populations a time-efficient method of identifying dysfunctional movement and determine whether the full 7-pattern model of the FMS should be considered.

Investigating the association between the lunar cycle and sleep, physiological, cognitive, and physical performance in children with Down syndrome.

Children with Down syndrome (DS) offer a compelling context within the fieldof human biology for examining potential lunar influences. While the exact mechanisms governing lunar effects are still under investigation, a growing body of scientific inquiry suggests possible connections between lunar phases and physiological, physical, and cognitive parameters. This investigation holds promise for uncovering the intricate interplay between lunar cycles (LCs) and the unique biology of children with DS. This study investigated the potential influence of the LC on physiological, physical, and cognitive parameters in children with DS, focusing on sleep patterns, physical performance, and cognitive abilities. Seventeen children with DS participated in this study. Sleep data, physical performance metrics, and cognitive test results were collected throughout the LC, including the new moon (NM), first quarter, full moon (FM), and third quarter. Statistical analyses were conducted to assess the differences in these parameters across lunar phases. Significant differences were observed in sleep patterns, with reduced total sleep time (P < 0.01) and sleep efficiency (P < 0.001) during the FM phase. Heart rates (HRs) before (P < 0.001) and after (P < 0.01) exercise also displayed pronounced changes during LC. Additionally, the reaction time (RT) exhibited a significant difference (P < 0.01) across the lunar phases. However, physical performance metrics, including squat jump (SJ), sprint, and 6-minute walk distance (6MWD), did not show significant variations. This study suggests that LC may have a moderating effect on sleep patterns, HR, and cognitive performance in children with DS. These findings have practical implications for caregivers and educators and highlight the importance of considering lunar-associated variations in planning schedules and interventions for children with DS.

Jumping towards field-based ground reaction force estimation and assessment with OpenCap

Low-cost and field-viable methods that can simultaneously assess external kinetics and kinematics are necessary to enhance field-based biomechanical monitoring. The aim of this study was to determine the accuracy and usability of ground reaction force (GRF) profiles estimated from segmental kinematics, measured with OpenCap (a low-cost markerless motion-capture system), during common jumping movements. Full-body segmental kinematics were recorded for fifteen recreational athletes performing countermovement, squat, bilateral drop, and unilateral drop jumps, and used to estimate vertical GRFs with a mechanics-based method. Eleven distinct performance-, fatigue-, or injury-related GRF variables were then validated against a gold-standard force platform. Across jumping movements, a total of six and three GRF variables were estimated with a bias or limits of agreement <5 % respectively. Bias and limits of agreement were between 5 and 15 % for seventeen and nineteen variables respectively. Moreover, we show that estimated force variables with a bias <15 % can adequately assess the within-athlete changes in GRF variables between jumping conditions (arm swing or leg dominance). These findings indicate that using a low-cost and field-viable markerless motion capture system (OpenCap) to estimate and assess GRF profiles during common jumping movements is approaching acceptable limits of accuracy. The presented method can be used to monitor force variables of interest and examine underlying segmental kinematics. This application is a jump towards researchers and sports practitioners performing biomechanical monitoring of jumping efficiently, regularly, and extensively in field settings.

A comparison between manual and automated event detection for a drop vertical jump task using motion capture

BackgroundThe use of movement screens as a clinical tool for injury risk assessment requires variables to be extracted across specific phases of interest. While manually selecting task events is the traditional method, automated event detection is an effective technique that maintains consistency across a cohort. This study aimed to examine variations in event identification, comparing manual detection and the application of an automated algorithm, with a specific focus on a drop vertical jump task. MethodsThirty participants cleared to return-to-play after anterior cruciate ligament reconstruction and thirty controls were tested. For the automated event detection, normalized vertical ground reaction force and the velocity of the sacrum marker were used to identify five events during the drop vertical jump: initial contact, end of loading, end of propulsion, second contact, and end of second loading. Two raters manually selected events and were compared to the event times of the automated algorithm. FindingsManual event detection exhibited excellent reliability Significant differences between manual and automated detection were observed, particularly at events indicating the lowest squat position (Event2 and Event5). Participants who had undergone anterior cruciate ligament reconstruction demonstrated larger differences than controls at Event5, correlating with significant squat depth disparities. InterpretationWhile manual event detection demonstrated reliability, automated algorithms revealed differences, specifically in events of the drop vertical jump involving the lowest squat position. The automated algorithm presents potential benefits in reducing processing time and enhancing accuracy for event identification, offering valuable insights for motion capture applications in clinical settings.

The Use of Free Weight Squats in Sports: A Narrative Review—Terminology and Biomechanics

There is substantial evidence indicating that increased maximum strength as a result of training with squats, particularly full and parallel squats, is associated with superior athletic capabilities, such as sprinting, jumping and agility. Although full and parallel squats have been strongly associated with sport performance, there is also some evidence that the use of partial squats may provide angle specific adaptations that are likely advantageous for specific sporting activities. Partial squats may be particularly advantageous when trained in conjunction with full or parallel squats, as this practice results in a greater training effect. There is a paucity of evidence that squatting is associated with excessive injuries to the knees, lower back, or other structures. Evidence does indicate that squatting, including full squats, can be undertaken safely, provided an appropriate training methodology is applied. Indeed, based on scientific data, the cost/benefit ratio indicates that squats should be recommended and should be a central strength training exercise for the preparation of athletes in most sports, particularly those requiring strong and powerful whole body and lower body movements.

Longitudinal changes in body composition, physiological characteristics, and motor performance of Paralympic goalball athletes

Research has yet to explore the long-term influences of physical fitness parameters on goalball and how COVID-19 affected athletes’ training program. This study evaluated the longitudinal changes in body composition (BC), postural balance (PB), maximal isometric grip force (MIGF), vertical jump (countermovement (CJ), squat jump (SJ), and peak oxygen consumption (VO2peak) in seven male Paralympic goalball athletes preparing for the Tokyo 2020 Paralympics. Six measurements were performed three times ([first] pre-lock down: January 2020, [second] post-lock down: September 2020, and [third] final follow-up: June 2021) on a variable-by-variable basis. Post hoc tests showed a significant improvement in BC at the third time point compared to the first and second time points. Concomitantly, PB and MIGF were significantly improved at the third time point compared to the first and second time points, respectively. A significant decline was observed in CJ and SJ heights at the second time point compared to the first time point whereas SJ height increased at the third time point compared to the second time point. No change was observed in CJ height at the third time point versus the second time point. There was a dramatic reduction in VO2peak at the second time point compared to the first time point. No change was observed in VO2peak occurred at the third time point versus pre and post lock down. Even with the disruption in the annual training plan due to COVID-19 pandemic, our participants maintained physical fitness levels with home-based exercises.

Functional movement screen test as an predictor for jumping tests performance and on-ice skating sprint in elite level ice hockey players.

Background. The main purpose of this research was to establish selected motor skills measured in off-ice and on-ice conditions in ice hockey players using the functional movement screen test, vertical jumps, and on-ice sprints. Material and Methods. The present study measured fifty-four (n=54) elite-level ice hockey players, competing in the top-level league in Poland (Polish Ice Hockey League, PHL) during the 2019/2020 season. Tests were divided into off-ice and on-ice protocols. The off-ice tests consisted of body composition measurements (including body weight, muscle mass, % of body fat), functional movement screening (FMS), measurements of jump height and power of the lower limbs, including countermovement jump (CMJ), squat jump (SJ), and drop jump (DJ). On-ice tests were divided into skating sprint testing measured in splits (0-10m, 10-30m), and total sprint between 0-30m. Furthermore, the maximal skating sprint was also measured between blue lines (15m). Results were correlated between FMS tests, vertical jump tests, and on-ice skating tests. The relationships between the variables were quantified using Pearson’s product-moment correlation. The aim of this study was to highlight off-ice protocols, which can best predict on-ice parameters. Fitness profiling involved division into forwards and defenders and the calculations were also performed for a whole group of hockey players. Results. The study showed a strong correlation between total points scored in FMS with the vertical jumps and skating sprints, especially in the defender group in CMJ jump height r = 0.69 (p &lt; 0.001) and 30m skating sprint r = 0.7 (p &lt; 0.001). Conclusions. The study found positive correlations between FMS tests and off-ice and on-ice parameters, showing that the FMS test could be used to predict ice skating performance.

The Effect of Half Squat Jump and Hurdle Jump Training on Short Distance Running of 60 Meters in Class IX Students of SMP Negeri 11 Makassar

This study aims to test the effect of half squat jump and hard jump training on short-distance running of 60 meters. The method used in this research is experimental research. This research was conducted at SMP Negeri 11 Makassar with participants in this research being students who were willing to follow all research procedures. The sample in this research was 20 students. The instrument used in this research was a 60-meter short-distance running test. Based on the results of data analysis, it can be concluded that the half squat jump training and hurdle jump training on the ability to run a short distance of 60 meters in class IX students of SMP Negeri 11 Makassar, obtained the average value of the half squat jump training group, namely 9.716, which is smaller than the average value of the half squat jump training group. The average for the hurdle jump training group was 9.082 with a value of t-count = 2.244 &gt; t-table = 2.101 or significant 0.038 &lt; 0.05. The results of this study show that hardle jump training is better than half squat jump training for short-distance running of 60 meters in class IX students of SMP Negeri 11 Makassar.

Household food insecurity among child and adolescent athletics practitioners: A cross-sectional, descriptive, and exploratory study

ObjectiveThe aim of the study was to explore the prevalence of food insecurity among child and adolescent athletics practitioners and to investigate factors associated with exercise performance, dietary habits, body composition, sleep, and socioeconomic status based on food security status. MethodsThis was a cross-sectional, descriptive, and exploratory study conducted in Campinas, São Paulo, Brazil, between June and July 2023. The convenience sample included children and adolescents (7–17 y old) of both sexes. We evaluated exercise performance, household food insecurity (HFI), dietary-related parameters, and other body composition, lifestyle, and social-related variables. Exercise performance was assessed using the counter movement jump (CMJ), squat jump (SJ), horizontal long jump (HLJ), 50-m sprint test (50-m ST) and throwing strength test (TST). The assessment of HFI was conducted using the food insecurity experience scale (FIES). Comparisons and associations were investigated based on food security status. ResultsThe total sample size was comprised of 138 children (n = 42; 30.4%) and adolescents (n = 96; 69.6%). We found an association between food security status and sex (X2(138,1) = 4.42; P = 0.036). SJ was higher in the food security group than in the HFI group (t(117) = 2.112; P = 0.037; ES = 0.39). Sleep- and dietary-related factors did not differ between the groups. ConclusionsIn summary, the prevalence of HFI among child and adolescent athletics participants was approximately 40%. Regarding exercise performance, SJ was better in the food security group than in the HFI group. Concerning dietary-related data, the HFI group had a lower number of meals per day than the food security group, and other dietary data did not differ between the groups. Body composition and sleep-related parameters were similar between the groups.

Commentary: A Patient-Specific Lower Extremity Biomechanical Analysis of a Knee Orthotic during a Deep Squat Movement

Commentary: A Patient-Specific Lower Extremity Biomechanical Analysis of a Knee Orthotic during a Deep Squat Movement

The repeated bout effect of traditional resistance training on cycling efficiency and performance

PurposeThis study examined the repeated bout effect of two resistance training bouts on cycling efficiency and performance.MethodsTen male resistance-untrained cyclists (age 38 ± 13 years; height 180.4 ± 7.0 cm; weight 80.1 ± 10.1; kg; VO2max 51.0 ± 7.6 ml.kg−1.min−1) undertook two resistance training bouts at six-repetition maximum. Blood creatine kinase (CK), delayed-onset of muscle soreness (DOMS), counter-movement jump (CMJ), squat jump (SJ), submaximal cycling and time-trial performance were examined prior to (Tbase), 24 (T24) and 48 (T48) h post each resistance training bout.ResultsThere were significantly lower values for DOMS (p = 0.027) after Bout 2 than Bout 1. No differences were found between bouts for CK, CMJ, SJ and submaximal cycling performance. However, jump height (CMJ and SJ) submaximal cycling measures (ventilation and perceived exertion) were impaired at T24 and T48 compared to Tbase (p < 0.05). Net efficiency during submaximal cycling improved at Bout 2 (23.8 ± 1.2) than Bout 1 (24.3 ± 1.0%). There were no changes in cycling time-trial performance, although segmental differences in cadence were observed between bouts and time (i.e. Tbase vs T24 vs T48; p < 0.05).ConclusionCyclists improved their cycling efficiency from Bout 1 to Bout 2 possibly due to the repeated bout effect. However, cyclists maintained their cycling completion times during exercise-induced muscle damage (EIMD) in both resistance training bouts, possibly by altering their cycling strategies. Thus, cyclists should consider EIMD symptomatology after resistance training bouts, particularly for cycling-specific technical sessions, regardless of the repeated bout effect.

Pengaruh latihan split squat jump, jump to box dan kelentukan terhadap kemampuan tendangan tengkong bailian wushu

This research highlights the strategic role of sports in improving the quality of human resources, focusing on Wushu as a branch of achievement. There is a dominant attack technique, Tengkong Bailian, which requires strength, speed, and precision. Plyometric exercises, such as Split Squat Jump and Jump To Box, are recognized as methods to increase muscle power. Flexibility is also considered crucial in sports activities, and the technical development of Wushu athletes requires the integration of plyometric training with a focus on strength, speed, and flexibility. This study tried to reveal the difference in the influence between the two plyometric exercise methods on the ability of Tengkong Bailian, taking into account the degree of flexibility. Results showed that both methods were effective, with Split Squat Jump superior at high flex, and Jump To Box more effective at low flex. The implication is that the integration of both training methods can promote optimal results in coaching Wushu athletes, with emphasis on individual characteristics and degree of flexibility. These findings provide guidance for Wushu trainers to develop effective exercise programs

Nocturnal Melatonin Ingestion Improves Soccer Players’ Short-Term Maximal Performances on the Following Day

ABSTRACT Purpose: Exogenous melatonin has been proven to have beneficial effects on sleep. A good sleep quality promotes recovery and improves physical performance. In this sense, the present study aimed to explore the potential effect of nocturnal melatonin ingestion on psycho-cognitive and short-term maximal performances, in the following morning. Method: Twelve professional soccer players (22.9 ± 1.3 years, 1.80 ± 0.05 m, and 72.0 ± 8.8 kg) volunteered to perform two separate testing sessions after either nocturnal melatonin or placebo ingestion. The next morning, participants performed the following psycho-cognitive and physical tests: Hooper’s index, reaction time, vigilance, handgrip strength (HG), squat jump (SJ), modified agility T-test (MAT) and Wingate anaerobic test (WanT). Rating of perceived exertion (RPE) and blood lactate [La] were recorded, respectively, immediately and 3 min after the WanT. Blood glucose [GL] was measured before and 3 min after WanT. Results: Compared with placebo, melatonin improved subjective sleep quality, short-term maximal performances (HG and SJ), reaction-time, as well as peak and mean WanT powers and decreased fatigue index and RPE scores. However, [La] and [GL] were not affected by melatonin ingestion. Conclusion: Nocturnal melatonin intake before sleep has beneficial effects on cognitive and physical performances the following day.

Detection of kinematic abnormalities in persons with knee osteoarthritis using markerless motion capture during functional movement screen and daily activities.

Background: The functional movement screen (FMS) has been used to identify deficiencies in neuromuscular capabilities and balance among athletes. However, its effectiveness in detecting movement anomalies within the population afflicted by knee osteoarthritis (KOA), particularly through the application of a family-oriented objective assessment technique, remains unexplored. The objective of this study is to investigate the sensitivity of the FMS and daily activities in identifying kinematic abnormalities in KOA people employing a markerless motion capture system. Methods: A total of 45 persons, presenting various Kellgren-Lawrence grades of KOA, along with 15 healthy controls, completed five tasks of the FMS (deep squat, hurdle step, and in-line lunge) and daily activities (walking and sit-to-stand), which were recorded using the markerless motion capture system. The kinematic waveforms and discrete parameters were subjected to comparative analysis. Results: Notably, the FMS exhibited greater sensitivity compared to daily activities, with knee flexion, trunk sagittal, and trunk frontal angles during in-line lunge emerging as the most responsive indicators. Conclusion: The knee flexion, trunk sagittal, and trunk frontal angles during in-line lunge assessed via the markerless motion capture technique hold promise as potential indicators for the objective assessment of KOA.

Relationships of lower extremity and trunk asymmetries in elite soccer players.

In light of previous research highlighting the prevalence of asymmetries in soccer players and possible links to injury risks, there is a crucial gap in the biomechanical understanding of complex relationships between lower extremity and trunk asymmetries in elite soccer players. The purpose of this study was to investigate the level, relationships, and differences among twelve different parameters of strength, morphological, and neuromuscular asymmetries in elite soccer players. Methods: Elite male soccer players (n = 25, age 21.7 ± 3.9years) were tested in the following tests: bilateral fluid distribution, hip flexor range of motion, postural stability, isokinetic strength of knee extensors and flexors, isometric lateral trunk rotation strength, eccentric strength of knee flexors, isometric bilateral strength of hip adductors, and vertical ground reaction force in counter-movement jump-free arms, counter-movement jump, squat jump, and drop jump tests. One-way ANOVA, Pearson's coefficient (r), and partial eta squared (η p 2) were used for data analysis. Results: Significant differences in asymmetries were found in elite soccer players (F11,299 = 11.01, p < .01). The magnitude of asymmetry over 10% was in postural stability and drop jump parameters. The lowest magnitudes of asymmetries were in the fluid distribution of the lower limbs and the vertical ground reaction force during the take-off phase in squat jumps. The highest asymmetries between the dominant and non-dominant sides were found in postural stability and drop jump. A total of eleven significant correlations (p < 0.05, r = 0.41-0.63, R2 = 0.17-0.40) were detected between the analyzed asymmetries in elite soccer players. The lateral trunk rotation asymmetries were significantly correlated to vertical ground reaction force asymmetries and knee extensors. Conclusion: Long-term exposure in elite soccer leads to unilateral biomechanical loading that induces abnormal strength and morphological adaptations in favor of the dominant side while linking lower limb and trunk strength asymmetries. By unraveling these complex relationships, we strive to contribute novel methods that could inform targeted training regimens and injury prevention strategies in the elite soccer community. The data should encourage future researchers and coaches to monitor and develop trunk strength linked to lower body kinematics.

Vertical Jump and Relative Strength are Strongly Associated with Change of Direction in Professional Male Basketball Players

Purpose: The aim of this study was to examine the predictors of change of direction (COD) in highly trained/national level male basketball players using field assessments.&#x0D; Methods: Eight professional male basketball players (age: 24.0 ± 5.5 years; body mass index (BMI): 24.1 ± 1.6 kg m-2) volunteered for participation in this study. All the evaluations were carried out during 2 sessions as follows: First day_1) body composition, 2) unilateral and bilateral squat jump (SJ) and countermovement (CMJ), and 3) Yo-Yo intermittent recovery test level 1 (Yo-Yo IR1); Second day_1) COD performance, and 2) one repetition maximum (1RM) hang clean (HC) and bench press (BP). A linear regression was performed to evaluate the determinants of COD amongst all other measured variables. Furthermore, we applied Pearson correlation coefficient and in the case of non-normally distributed variables, Spearman’s correlation coefficient for the selected variables.&#x0D; Results: The linear regression indicated that only SJ height was a significant determinant of COD (R2 = 58.8%, p = 0.016). Significant correlations were identified between COD test and SJ (r = -0.75, p = 0.034; very large), and relative HC 1 RM (r = -0.74, p = 0.038; very large).&#x0D; Conclusions: The associations found between COD performance and physical parameters should be considered when developing athletic conditioning programs. Especially, the vertical jump heigh could explain the greatest variability in COD performance..

The Impact of the Soccer Training Season on the Body Composition and Physical Performances of Young Soccer Players

The purpose of this research was to prove the effectiveness of a soccer training program during a macrocycle (preparation and competition season) on the body composition and physical performances of young players. The research was conducted with a sample of 24 soccer players in two age groups: U15 (n=12) and U17 (n=12). The initial testing took place prior to the start of the preseason, whereas the final testing was performed after four months of training. The results prove that the soccer training program for the U15 age range causes important significant differences in the isokinetic force: peak torque flexion and peak torque extension. No significant changes were seen in body composition (body height/mass and muscle and fat mass) or vertical jump (Squat Jump - SJ, Counter-Movement Jump - CMJ, Maximal Counter-Movement Jump - CMJmax). The results also prove that the U17 soccer training program causes important statistical differences in muscle mass, fat mass, SJ, CMJ, CMJmax, and peak torque flexion, but there were no statistically significant changes in peak torque extension or body height/mass of the U17 soccer players. This research shows that the sensitive phase for relevant improvements in explosive force occurs after the age of 15 years, a period that is characterized by the dramatic development of muscle mass.

Conventional video recordings dependably quantify whole-body lifting strategy using the Stoop-Squat-Index: A methods comparison against motion capture and a reliability study

Whole-body lifting strategies could be derived from conventional video recordings using the Stoop-Squat-Index, which quantifies the ratio between trunk forward lean and lower extremity joint flexion from 0 (full squat) to 100 (full stoop). The purpose of this study was to compare Stoop-Squat-Indices derived from conventional video recordings to those from a three-dimensional marker-based motion capture system and to evaluate interrater and intrarater reliability of the video-based approach.Thirty healthy participants lifted a 5-kg box under different conditions (freestyle, squat, stoop). Kinematic data were recorded using a Vicon motion capture system (serving as reference standard) and an iPad camera. Stoop-Squat-Indices over the entire lifting cycle were derived separately from both approaches. Agreement was assessed using mean differences (video minus motion capture) and limits of agreement. Reliability was investigated by calculating intraclass correlation coefficients (ICC) and minimal detectable changes (MDC) over the course of the lifting cycle. Systematic errors were identified with Statistical Parametric Mapping-based T-tests.Systematic errors between the video-based and the motion capture-based approach were observed among all conditions. Mean differences in Stoop-Squat-Indices over the lifting cycle ranged from −6.9 to 3.2 (freestyle), from −1.8 to 5.3 (squat) and from −2.8 to −1.1 (stoop). Limits of agreement were lower when the box was close to the floor, and higher towards upright standing. Reliability of the video-based approach was excellent for most of the lifting cycle, with ICC above 0.995 and MDC below 3.5.These findings support using a video-based assessment of Stoop-Squat-Indices to quantify whole-body lifting strategy in field.