The muscle contractile properties in female soccer players: inter-limb comparison using tensiomyography.

OBJECTIVE: The present study aimed to: i) determine the contractile properties of the major lower limb muscles in female soccer players using tensiomyography; ii) investigate inter-limb differences; and iii) compare inter-limb differences between different selections and playing positions. METHODS: A total of 52 female soccer players (A team; U19 and U17) were recruited. The vastus lateralis (VL), vastus medialis (VM), rectus femoris (RF), biceps femoris (BF), gastrocnemius medialis (GM), lateralis (GL) and tibialis anterior (TA) of both lower limbs were evaluated. RESULTS: When the entire sample was assessed regardless of selection or playing position, there were significant inter-limb differences in all measured muscles except BF. Compared to the non-dominant limb, the dominant limb had higher delay time in VL (p=0.008), while showing lower values in VM (p=0.023), GL (p=0.043) and GM (p=0.006). Contraction time was lower in the RF of the dominant limb (p=0.005) and VM (p=0.047), while showing higher values in VL (p=0.036) and TA (p<0.001) as compared to the non-dominant limb. CONCLUSION: Given the differences found between the limbs in the whole sample studied, it is necessary to examine both limbs to gather a more in-depth understanding of underlying mechanisms related to neuromuscular functions in female soccer players. LEVEL OF EVIDENCE: Prognostic study, Level II.

Effects of Moderate Altitude Training Combined with Moderate or High-altitude Residence.

We aimed to identify potential physiological and performance differences of trained cross-country skiers (V˙o2max=60±4 ml ∙ kg-1 ∙ min-1) following two, 3-week long altitude modalities: 1) training at moderate altitudes (600-1700 m) and living at 1500 m (LMTM;N=8); and 2) training at moderate altitudes (600-1700 m) and living at 1500 m with additional nocturnal normobaric hypoxic exposures (FiO2 =0.17;LHTM; N=8). All participants conducted the same training throughout the altitude training phase and underwent maximal roller ski trials and submaximal cyclo-ergometery before, during and one week after the training camps. No exercise performance or hematological differences were observed between the two modalities. The average roller ski velocities were increased one week after the training camps following both LMTM (p=0.03) and LHTM (p=0.04) with no difference between the two (p=0.68). During the submaximal test, LMTM increased the Tissue Oxygenation Index (11.5±6.5 to 1.0±8.5%; p=0.04), decreased the total hemoglobin concentration (15.1±6.5 to 1.7±12.9 a.u.;p=0.02), and increased blood pH (7.36±0.03 to 7.39±0.03;p=0.03). On the other hand, LHTM augmented minute ventilation (76±14 to 88±10 l·min-1;p=0.04) and systemic blood oxygen saturation by 2±1%; (p=0.02) with no such differences observed following the LMTM. Collectively, despite minor physiological differences observed between the two tested altitude training modalities both induced comparable exercise performance modulation.

Isometric Trunk Strength Assessment of Athletes: Effects of Sex, Sport, and Low Back Pain History.

CONTEXT: The importance of isometric trunk strength (ITS) among sport science professionals is higher than its actual reported effect size on either performance or low back pain (LBP) occurrence. OBJECTIVE: To provide normative values of ITS and strength ratios, and to evaluate the effect of sex, sports discipline, and LBP status. DESIGN: Crossover study. SETTING: University research laboratory. PARTICIPANTS: Five hundred and sixty-seven elite athletes (186 females) with and without a history of LBP from different sports. MAIN OUTCOME MEASURE: Participants underwent ITS testing for trunk flexors, extensors, and lateral flexors. Normalized maximal strength (in newton meter per kilogram) and strength ratios were calculated. Differences between sex, LBP, and sport disciplines were assessed with 3-way analysis of variance (sex × LBP status × 7 sport categories) and partial eta-squared (ηp2) effect size. The predictive validity of ITS for LBP was checked with receiver operating characteristics (area under the curve). RESULTS: The authors found significant differences in extensor and flexor ITS in favor of male athletes (medium ηp2, P < .05), while sex differences in lateral flexion ITS had a low size effect (P < .05). A low size effect was also observed for the differences in strength ratios extensors/flexors (mean 1.47; 95% confidence interval, 1.45-1.50) and left flexors/right flexors (mean 0.99; 95% confidence interval, 0.98-1.01) among sexes. The sport discipline-related differences generally had a low size effect. No significant differences in ITS were found between LBP and LBP-free athletes. Only 50% to 58% of athletes (area under the curve, 0.501-0.582) were correctly classified as LBP or LBP-free using different ITS and strength ratio variables. CONCLUSIONS: ITS and strength ratios have low predictive validity for LBP history but may discriminate between sex and sport disciplines. Our data are a useful reference point for meaningful individual results interpretation when athletes are evaluated during training or rehabilitation.

The Relationship Between Army Physical Fitness and Functional Capacities in Infantry Members of the Slovenian Armed Forces.

ABSTRACT: Simenko, J, Kovcan, B, Pori, P, Vodicar, J, Vodicar, M, and Hadzic, V. The Relationship between army physical fitness and functional capacities in infantry members of the Slovenian Armed Forces. J Strength Cond Res 35(12): 3506-3512, 2021-The primary purpose of this study was to determine the relationship between traditional army physical fitness test (APFT) and a novel functional testing battery that included countermovement jump (CMJ) testing, stork balANce test, pUll-ups, single leg hAmstring bridge test, and loaded prone pLank test-MANUAL battery. The secondary purpose was to explore additional baseline fitness aspects traditionally not covered by APFT. This cross-sectional study involved 181 Slovenian Armed Forces (SAF) infantry members (age 31.4 ± 6.1 years) that were tested using both the regular annual APFT and the MANUAL battery (testing was conducted 2 weeks apart). At the significance level of p ≤ 0.05, significant but weak associations between the MANUAL testing battery and APFT battery (0.2 ≤ r < 0.5; p ≤ 0.05) were observed. The MANUAL battery has highlighted possible hamstring (less than 20 repetitions on a single leg bridge test in 26% of SAF infantry members) and posterior shoulder pull-up muscle weakness (mean score 5 ± 4 pull-ups). Functional predictors from the MANUAL explained only 33.6% of the APFT score (R2 = 0.336). Significant predictors of APFT score were single leg hamstring left (p = 0.048), loaded plank (p = 0.049), number of pull-ups (p < 0.001), CMJ (p = 0.01), and loaded CMJ (p = 0.026). The findings suggest that higher APFT marks are associated with better performance on the MANUAL tests and indicate the problem of hamstring and pull-up muscle weakness. The general recommendation is that the physical condition military programs should include more exercises to strengthen those muscle groups.

Are Change-of-Direction Speed and Reactive Agility Independent Skills Even When Using the Same Movement Pattern?

Coh, M, Vodicar, J, Zvan, M, Simenko, J, Stodolka, J, Rauter, S, and Mackala, K. Are change-of-direction speed and reactive agility independent skills even when using the same movement pattern? J Strength Cond Res 32(7): 1929-1936, 2018-The purpose of this investigation was to determine whether there are differences between the 2 approaches to quantifying agility (preplanned vs. unplanned response) when reacting to a stimulus in an identical spatial scenarios. The study involved 45 male and 31 female trained athletes (age 21.2 ± 1.78 and 20.6 ± 1.27 years, body height 181.6 ± 8.31 and 167.7 ± 5.03 cm, and body mass 78.9 ± 11.33 and 63.3 ± 8.65 kg, respectively). A light-based reactive training system was used to measure the time to completion in a task that assessed agility by change-of-direction speed (CODS) in a preplanned condition and reactive agility (RA) in an unplanned condition across 4 spatial configurations. Sprint performance in a 30-m sprint and lower limb reactive power in a 10-m single leg jump test was also measured. Significant differences (p ≤ 0.05) were found between men and women in all tests and between performance in the CODS and RA condition for each spatial configuration. Significant correlations were observed between 30-m starting sprint speed and CODS and RA performance measured in a semicircle (r = 0.62, r = 0.60) and lateral (r = 0.54, r = 0.58) configuration in male athletes. The present findings suggest that CODS and RA are 2 different and independent skill domains that define agility. These qualities should be diagnosed by discrete assessments and enhanced by different training methodologies.

Cardiorespiratory Responses of Adults and Children during Normoxic and Hypoxic Exercise.

We aimed to elucidate potential differential effects of hypoxia on cardiorespiratory responses during submaximal cycling and simulated skiing exercise between adults and pre-pubertal children. Healthy, low-altitude residents (adults, N=13, Age=40±4yrs.; children, N=13, age=8±2yrs.) were tested in normoxia (Nor: PiO2=134±0.4 mmHg; 940 m) and normobaric hypoxia (Hyp: PiO2=105±0.6 mmHg; ~3 000 m) following an overnight hypoxic acclimation (≥12-hrs). On both days, the participants underwent a graded cycling test and a simulated skiing protocol. Minute ventilation (VE), oxygen uptake (VO2), heart rate (HR) and capillary-oxygen saturation (SpO2) were measured throughout both tests. The cycling data were interpolated for 2 relative workload levels (1 W·kg-1 & 2 W·kg-1). Higher resting HR in hypoxia, compared to normoxia was only noted in children (Nor:78±17; Hyp:89±17 beats·min-1; p<0.05), while SpO2 was significantly lower in hypoxia (Nor:97±1%; Hyp:91±2%; p<0.01) with no between-group differences. The VE, VO2 and HR responses were higher during hypoxic compared to normoxic cycling test in both groups (p<0.05). Except for greater HR during hypoxic compared to normoxic skiing in children (Nor:155±19; Hyp:167±13 (beats·min-1); p<0.05), no other significant between-group differences were noted during the cycling and skiing protocols. In summary, these data suggest similar cardiorespiratory responses to submaximal hypoxic cycling and simulated skiing in adults and children.

The association between unilateral and bilateral performance-related measures in elite female soccer players: a multifaceted investigation.

Purpose: The present study aimed to investigate a) the associations between bilateral performance utilizing countermovement jump (CMJ), squat jump (SJ), speed and unilateral CMJ, isokinetic peak torque in knee extension and flexion with angular velocities of 60°/s and 180°/s and tensiomyography (TMG) parameters; b) whether the asymmetries derived from unilateral tests are associated with bilateral CMJ, SJ and speed in elite female soccer players. Methods: Thirty-five elite female soccer players (average age: 20 ± 5 years) completed CMJ, SJ, speed, isokinetic muscle strength and TMG tests. Results: Compared to the non-dominant leg, the dominant leg demonstrated greater peak torque output in both knee flexion (7.4%) and knee extension (5.6%) isokinetic tasks, as well as m. vastus medialis contraction time (7.6%), and soccer-specific agility test (4.1%). Conversely, the hamstring to quadriceps peak torque ratio at 180°/s (8.5%) was significantly greater in the non-dominant leg. The associations between CMJ, SJ and speed performance were positive and ranged from weak (r = 0.350) to high (r = 0.710). For speed and TMG-derived variables, correlations were negative and ranged from weak (r = -0.345, p = 0.042, for vastus medialis contraction time) to moderate (r = -0.530, p = 0.001, for biceps femoris contraction time). Furthermore, both bilateral CMJ and SJ negatively correlated with TMG-derived variables, ranging from weak (r = -0.350, p = 0.039, for vastus lateralis contraction time) to moderate (r = -0.537, p = 0.003, for rectus femoris contraction time). Conclusion: The overall significant, albeit inconsistent, correlations between the diverse performance scores obtained highlight the necessity for a multifaceted and thorough diagnostic strategy in female soccer players.

The effect of the surgical treatment of brachycephalic obstructive airway syndrome on the thermoregulatory response to exercise in French bulldogs: a pilot study.

Introduction: Due to altered anatomy of the upper respiratory tract, brachycephalic dogs exhibit increased airway resistance and reduced surface area for evaporative heat loss, predisposing them to respiratory and thermoregulatory problems, a syndrome referred to as Brachycephalic Obstructive Airway Syndrome (BOAS). Compared to non-brachycephalic dogs, brachycephalic breeds are more susceptible to heat-related injuries even at low ambient temperatures and relatively low physical activity levels. Surgical treatment alleviates clinical signs, potentially improving dogs' thermoregulatory ability with BOAS. Our study aimed to investigate the thermoregulatory response in French bulldogs before and after the surgical correction of BOAS, respectively. Methods: Thirteen dogs were exposed to dynamic exercise on a treadmill and the dynamics of their rectal temperature (RT) and heart rate (HR) was measured. The experiment was performed in two independent sessions, before and after the surgical treatment. The test consisted of two consecutive 5-min walks at a speed of 2.5 km/h, first at an inclination of 0% and the second at an inclination of 5%, and a 30-min recovery period. Rectal temperature and HR were measured before the start of the test (t0), at the end of the first (t1) and the second part (t2), and 15 min (t3) and 30 min (t4) in the recovery. Results: A significant increase in RT and HR was observed during exercise and recovery compared to the resting values, implying that the exercise intensity was sufficient to challenge the thermoregulatory response. The increase of RT was significantly lower during both parts (t1: p = 0.004; t2: p < 0.001) of exercise after the surgical treatment than before the treatment. Although a trend of lower RT after recovery was observed compared to before the surgery, it did not reach statistical significance. Similarly to RT, the HR was significantly lower during exercise after the first (p = 0.020) and the second part (p = 0.011) of exercise after the surgery compared to before the surgery but did not reach significance in the recovery. Conclusion: Surgical treatment of BOAS can improve thermoregulation during exercise in French bulldogs with BOAS.

Correction: Mackala et al. Evaluation of the Pre-Planned and Non-Planed Agility Performance: Comparison between Individual and Team Sports. Int. J. Environ. Res. Public Health 2020, 17, 975.

Jozef Simenko was not included as an author in the original publication [...].

Reliability and validity of 30-15 intermittent fitness test for cardiorespiratory fitness assessment among infantry members of Slovenian armed forces: A study protocol.

Introduction: Cardiorespiratory fitness (CRF) testing is routinely performed by most armed and tactical forces around the world as part of their recruitment process for new members or simply as an annual examination of their personnel. A 2-mile run (2MR) test is among the most commonly used. However, as it is performed outdoors, weather, climate, and terrain can influence the results and often limit the maximum performance. Also, this test has been shown to be difficult for individuals because the pacing strategy is self-paced. As such, it does not reflect the real situation on the battlefield, where most activities are externally driven by the environment and the enemy. Therefore, we believe that the 30-15 Intermittent Fitness Test (30-15IFT) may be a suitable tool for measuring CRF and battle readiness of military personnel. Moreover, given the importance of visual attention to military personnel we aim to investigate the differences in visual attention between better and less physically prepared infantry members and its corresponding response to maximal endurance running test. Methods and analysis: This randomized cross-over study using a within-subjects test-retest design will enroll 32 infantry members of the Slovenian Armed Forces. To investigate the reliability and validity of the 30-15IFT test, an incremental treadmill test (TR), a 2MR test, and two identical 30-15IFT will be performed in randomized order. Additionally, participants will be subsequently divided into two groups based on their score on the Army Physical Fitness Test (APFT), whereas differences in visual attention will be assessed by using the d2 test. The primary analysis will assess differences in key physiological outcomes between the different CRF tests (TR vs. 2MR vs. 30-15IFT). In addition, the relative reliability of all dependent variables between two 30-15IFT trials will be estimated by interclass correlation coefficient (ICC), while relationship between maximal oxygen uptake, heart rate and maximal running speed of 30-15IFT, TR and 2MR will be assessed using Pearson's correlation. Ethics and dissemination: Ethical approval was obtained from the National Medical Ethics Committee (reference number: 0120-495/2021/6). The results of the proposed study will be disseminated through publication in peer-reviewed journals. Clinical Trial Registration: [www.ClinicalTrials.gov], identifier [NCT05218798].

Tissue Flossing Around the Thigh Does Not Provide Acute Enhancement of Neuromuscular Function.

Nowadays, various methods are used for acute performance enhancement. The most recent of these is tissue flossing, which is becoming increasingly popular for both performance enhancement and rehabilitation. However, the effects of flossing on athletic performance have not been clearly demonstrated, which could be due to differences in the methodology used. In particular, the rest periods between the end of the preconditioning activity and the performance of the criterion task or assessment tools varied considerably in the published literature. Therefore, the present study aimed to investigate the effects of applying tissue flossing to the thigh on bilateral countermovement jump performance and contractile properties of vastus lateralis (VL) muscle. Nineteen recreational athletes (11 males; aged 23.1 ± 2.7 years) were randomly assigned to days of flossing application (3 sets for 2 min of flossing with 2 min rest between sets) with preset experimental pressure (EXP = 95 ± 17.4 mmHg) or control condition (CON = 18.9 ± 3.5 mmHg). The first part of the measurements was performed before and after warm-up consisting of 5 min of cycling followed by dynamic stretching and specific jumping exercises, while the second part consisted of six measurement points after flossing application (0.5, 3, 6, 9, 12, 15 min). The warm-up improved muscle response time (VL = -5%), contraction time (VL = -3.6%) muscle stiffness (VL = 17.5%), contraction velocity (VL = 23.5%), jump height (13.9%) and average power (10.5%). On the contrary, sustain time, half-relaxation time and take-off velocity stayed unaltered. Flossing, however, showed negative effects for muscle response time (F = 18.547, p < 0.001), contraction time (F = 14.899, p < 0.001), muscle stiffness (F = 8.365, p < 0.001), contraction velocity (F = 11.180, p < 0.001), jump height (F = 14.888, p < 0.001) and average power (F = 13.488, p < 0.001), whereas sustain time, half-relaxation time and take-off velocity were unaffected until the end of the study protocol regardless of condition assigned and/or time points of the assessment. It was found that the warm-up routine potentiated neuromuscular function, whereas the flossing protocol used in the current study resulted in fatigue rather than potentiation. Therefore, future studies aimed to investigate the dose-response relationship of different configurations of preconditioning activities on neuromuscular function are warranted.

The reliability, validity and usefulness of the 30-15 intermittent fitness test for cardiorespiratory fitness assessment in military personnel.

The objectives of this study were to investigate the reliability, validity, and usefulness of the 30-15 intermittent fitness test (30-15IFT) in soldiers. The 34 infantry members of the Slovenian armed forces were recruited as participants. Participants performed the continuous incremental treadmill test (TR), a 2-mile run (2MR) test, and two 30-15IFT tests. Additionally, participants were divided into a highest-scoring group (HSG) and a lowest-scoring group (LSG) based on their scores on the Army Physical Fitness Test. A very high reliability ratings were observed for 30-15IFT measures, as follows: end-running speed (ERS) ERSIFT (ICC = 0.971), maximal heart rate (HRmax) HRmaxIFT (IC = 0.960), and maximal relative oxygen consumption (VO2max) VO2max-IFT (ICC = 0.975). Although 30-15IFT measures demonstrated high correlations (r = 0.695-0.930) to the same measures of TR test, ERS, HRmax and VO2max were higher in the 30-15IFT (p > 0.05). Furthermore, ERSIFT and predicted VO2maxIFT were higher in HSG compared to LSG, whereas HRmax did not differ. The results of this study show that the 30-15IFT test is a reliable, valid and useful tool for assessing cardiorespiratory fitness in the armed forces. Moreover, the ERS and predicted VO2max values derived from the 30-15IFT could be considered more sensitive markers of combat readiness than the parameters derived from the TR and 2MR tests.Trial registration number: NCT05218798.

The Effect of Height on Drop Jumps in Relation to Somatic Parameters and Landing Kinetics.

The aim of this study was to assess the effect of drop height and selected somatic parameters on the landing kinetics of rebound jumps in force and power production, performed by male and female student athletes. Twenty female and forty male students with a sports background participated in the experiment (mean and standard deviation (± SD): age 20.28 ± 1.31 years, height 166.78 ± 5.29 cm, mass 62.23 ± 7.21 kg and 21.18 ± 1.29, 182.18 ± 6.43, 78.65 ± 7.09). Each participant performed three maximal jumps on two independent and synchronized force platforms (Bilateral Tensiometric Platform S2P) at each of the two assigned drop-jump heights (20-, and 40-, cm for female and 30-, and 60-, cm for the male special platform). Significant between-sex differences were observed in all variables of selected somatics, with men outperforming women. Statistically significant differences were noted in four parameters, between men and women, in both DJs from 20/40 and 30/60 cm. The height of the jump was 6 cm and 4 cm higher for men. A slightly higher statistical significance (p = 0.011) was demonstrated by the relative strength (% BW) generated by the left limb in both men and women. Only women showed a significant relationship between body mass, body height, and five parameters, dropping off of a 20 cm box. In men, only the left leg-relative maximal F (p =-0.45)-showed a relationship with body mass. There were no relationships between the above-mentioned dependencies in both groups, in jumps from a higher height: 40 cm and 60 cm. From a practical application, the DJ with lower 20/30 cm or higher 40/60 cm (women/men) respectively emphasizes either the force or power output via an increase in the velocity component of the rebound action or increased height of the DJ jump.

Body Composition in International Sprint Swimmers: Are There Any Relations with Performance?

The paper addresses relations between the characteristics of body composition in international sprint swimmers and sprint performance. The research included 82 swimmers of international level (N = 46 male and N = 36 female athletes) from 8 countries. We measured body composition using multifrequency bioelectrical impedance methods with "InBody 720" device. In the case of male swimmers, it was established that the most important statistically significant correlation with sprint performance is seen in variables, which define the quantitative relationship between their fat and muscle with the contractile potential of the body (Protein-Fat Index, r = 0.392, p = 0.007; Index of Body Composition, r = 0.392, p = 0.007; Percent of Skeletal Muscle Mass, r = 0.392, p = 0.016). In the case of female athletes, statistically significant relations with sprint performance were established for variables that define the absolute and relative amount of a contractile component in the body, but also with the variables that define the structure of body fat characteristics (Percent of Skeletal Muscle Mass, r = 0.732, p = 0.000; Free Fat Mass, r = 0.702, p = 0.000; Fat Mass Index, r = -0.642, p = 0.000; Percent of Body Fat, r = -0.621, p = 0.000). Using Multiple Regression Analysis, we managed to predict swimming performance of sprint swimmers with the help of body composition variables, where the models defined explained 35.1 and 75.1% of the mutual variability of performance, for male and female swimmers, respectively. This data clearly demonstrate the importance of body composition control in sprint swimmers as a valuable method for monitoring the efficiency of body adaptation to training process in order to optimize competitive performance.

Evaluation of the Pre-Planned and Non-Planed Agility Performance: Comparison between Individual and Team Sports.

This study assessed differences in agility performance between athletes of team and individual sports by assessing change-of-direction speed (CODS) as pre-planned agility and reactive agility (RA) as non-planed in different spatial configurations. The study involved 36 individual (sprint, hurdles, jumping, tennis, and judo) and 34 team (soccer, basketball, and handball) athletes. CODS and RA were measured with a light-based reactive training system in a frontal (FR), universal (UN), semicircular (SC), and lateral (LA) design. Lower limb power and sprint performance were also measured in a 10 m single leg jump test and 15 m sprint. Individual athletes showed significantly better performance in three of the eight agility tests: LA-RA, UN-RA, and SC-CODS (p < 0.008, p < 0.036, and p < 0.027, respectively) and were found to present stronger correlations (p < 0.01) between jump test performance and the CODS condition. Team athletes showed stronger associations between sprint performance and the CODS condition. In the RA condition both jump and sprint performance showed stronger correlations in the group of individual athletes. Agility performance as measured by CODS and RA should improve with enhanced of motor proficiency. Finally, the tests applied in this experiment seem to be multidimensional, but require spatio-temporal adjustment for their implementation, so that they meet the requirements of the particular sport.

Relation of Lean Body Mass and Muscle Performance to Serum Creatinine Concentration in Hemodialysis Patients.

INTRODUCTION: Serum creatinine concentration is an important uremic marker and predictor of survival in dialysis patients. This cross-sectional case-control study was made to quantitatively describe the relation between lean body mass (LBM), physical performance measures, and serum creatinine values. METHODS: Ninety hemodialysis patients and 106 controls were measured by bioimpedance spectroscopy, handgrip strength, sit-to-stand test, and biochemical serum tests. Univariate and multivariate general linear models were used to analyze quantitative relations. RESULTS: At univariate regression LBM accounted for 13.6% variability of serum creatinine concentration. In adjusted analyses with age, height, and body mass, LBM persisted as the only significant predictor of midweek predialysis serum creatinine concentration. Physical performance measures handgrip strength and sit-to-stand performance did not improve prediction of serum creatinine. With addition of serum urea concentration and residual diuresis the predictive value of the regression model improved to account for 45% of serum creatinine variability. Each kg of LBM was associated with 7.7 µmol/l increase in creatinine concentration (95% CI 3.4-12.1, p=0.001). CONCLUSION: Bioimpedance derived LBM has a significant linear relation with predialysis serum creatinine concentrations. Hereby described quantitative relation should help clinicians to better evaluate observed creatinine concentrations of hemodialysis patients when bioimpedance derived LBM is available.

Soccer Players Cultural Capital and Its Impact on Migration.

The purpose of this study was to identify factors that constituted the cultural capital among soccer players. We assumed that in the increasingly globalized world of professional soccer, a player's success would often depend on migrating and adjusting to life in other countries. Willingness to migrate and successful adjustment are tied to player's previous attitudes and/or behaviours (habitus), significant support from others, including family members, and previous experiences and success in sports and education. Our hypothesised model of the cultural capital was based on the Pierre Bourdieu's theoretical framework. It consisted of 26 variables related to three sets of factors: soccer experiences, a family context and support, and educational achievements of the players and their parents. The model was tested using a sample of 79 current soccer coaches who also had been players at the elite level. A factor analysis was used to empirically verify the content of the hypothetical model of the soccer players' cultural capital. Nine latent factors were extracted and together, they accounted for 55.01% of the total model variance. Individual factors obtained showed a sufficient level of substantial connection. The Cronbach's alpha value of 0.77 confirmed the internal consistency of the operationalised variables in the hypothetical model. In addition, the impact of these aforementioned life dimensions on the migration of soccer players was studied. The results of the binary logistic regression analysis showed that the first factor of the hypothetical model (F1) had 2.2 times and the second factor (F8) had 3.9 times higher odds for migration abroad. Sociocultural findings using this new assessment approach could help create better "success conditions" in the talent development of young players.

Effect of an Arm Swing on Countermovement Vertical Jump Performance in Elite Volleyball Players: FINAL.

The aim of this study was to determine how elite volleyball players employed the arm swing (AS) to enhance their jump performance. The study assessed how the AS influenced the duration and magnitude of the vertical ground reaction force (VGRF) during the main phases (preparatory, braking and accelerating) of the countermovement vertical jump (CMVJ), the starting position of the body at the beginning of the accelerating phase and the moment when the AS began contributing to increasing the jump height. Eighteen elite volleyball players performed three CMVJs with and without an AS. Kinetics and kinematics data were collected using two Kistler force plates and the C-motion system. The time and force variables were evaluated based on the VGRF, and the position of the body and the trajectory of the arm movement were determined using kinematic analysis. The AS improved the CMVJ by increasing the jump height by 38% relative to jumping without an AS. The AS significantly shortened the braking phase and prolonged the accelerating phase, however, it did not influence the preparatory phase or the overall jump duration. The AS also significantly increased the average force during the accelerating phase as well as the accelerating impulse. The AS upward began at 76% into the overall jump duration. The AS did not influence the body position at the beginning of the accelerating phase. These findings can be used to improve performance of the CMVJ with the AS and in teaching beginning volleyball players proper jumping technique.