Adolescent Female Volleyball Players Research Articles

Hormonal and psychological influences on performance anxiety in adolescent female volleyball players: a multi-approach study.

The neuroendocrine system has important implications for affiliation behavior among humans and can be used to assess the correlation between social relationships, stress, and health. This can be influenced by social closeness; this aspect is the closeness towards another individual or a group of individuals such as a sports team. Sports performance anxiety is considered an unpleasant emotional reaction composed of physiological, cognitive, affective, and behavioral components. This motivates us to learn about the process that can influence the outcome of competition. Hormones and genetics would seem to influence outcome and performance. In this regard, many studies have focused on the exercise response as a function of ovarian hormones and it has been observed that progesterone is a hormone that plays a key role in reducing anxiety, and thus stress, in humans and other animals. On the other hand, high cortisol concentrations are known to contribute to increased anxiety levels. However, the salivary alpha-amylase (sAA) enzyme has been suggested as marker of acute stress than cortisol. Genetics also seem to influence anxiety and stress management as in the case of brain-derived neurotrophic factor (BDNF) and striatal dopamine transporter (DAT). Therefore, the study aims to investigate social closeness, as a measure of sports team cohesion that can influence athletes' performance results, and its ability to influence the secretion of hormones, such as progesterone and cortisol, that affect the management of sports anxiety while also taking into account genetic background during a volleyball match. Twenty-six female volleyball players who volunteered participated in this study (mean ± SD: age, 12.07 ± 0.7 years), and played in the final of the provincial volleyball championship in Palermo. All girls were during the ovarian cycle, in detail between the follicular and early ovulatory phases. The results showed a significant decrease in salivary cortisol only in the winning group (p < 0.039). In fact, whilst in the latter the pre-match level was 7.7 ng/ml and then decreased to 4.5 ng/ml after the match, in the losers group change was not statistically significant (7.8 ng/ml vs 6.6 ng/ml pre- and post-match). As to the sAA concentration, the winning team showed a statistically significant variation between pre- and post-match than the losers (166.01 ± 250 U/ml vs 291.59 ± 241 U/ml) (p = 0.01). Analyzing the results of the SAS-2 psychological test it is highlighted that, on average, the loser group was more anxious than the winning group, and this contributed to the final result. In conclusion, there is strong evidence supporting the state of the art that many factors can affect performance anxiety and thus the performance itself.

Effects of an 8-Week Kettlebell Training Program on the Physical Fitness and Anaerobic Power Related to Performance in Adolescent Female Volleyball Players

Effects of an 8-Week Kettlebell Training Program on the Physical Fitness and Anaerobic Power Related to Performance in Adolescent Female Volleyball Players

Effects of 10 months of training on salivary mitochondrial DNA copy number in adolescent female volleyball players

Effects of 10 months of training on salivary mitochondrial DNA copy number in adolescent female volleyball players

Ball-To-Hand Contact Forces Increase Modeled Shoulder Torques during a Volleyball Spike.

The volleyball spike is repeated many times in practices and games, presenting a high risk of overuse injury. Previous biomechanical analyses estimating forces on the shoulder during spiking have not included the force exerted on the arm by the ball, because no practical method exists to estimate the contact force between the ball and the hand. The objective of the study was to model the internal shoulder joint reactions while including the measured ball contact force. Ten adolescent female volleyball players performed spikes while we recorded 3D motion capture data for both ball and player. Using an impulse-momentum analysis, we estimated the ball contact force, then included the force in a computational simulation model to estimate the torques produced by the shoulder. The study found that post-contact ball velocities range from 8.6 m/s - 18.2 m/s with net forces between 238 N - 672 N. Most notably, when the ball contact force was included, the average modeled internal shoulder torque to internally rotate the arm increased from -26 N-m to +44 N-m (p < 0.001). These data suggest that neglecting the contact force may risk misinterpreting connections between biomechanics and injury due to spiking. More accurate joint mechanics models will lead to better injury prevention recommendations for volleyball players of all ages.

Countermovement Jump Performance Is Related to Ankle Flexibility and Knee Extensors Torque in Female Adolescent Volleyball Athletes.

Ankle flexibility and isokinetic knee torque/power generating capacity were previously suggested to contribute or to be correlated to the vertical countermovement jump (CMJ) performance. The aim of this study was to investigate the effect of the passive ankle joint dorsi flexion (θPDF) and the knee muscle's isokinetic torque and power on the CMJ in adolescent female volleyball players. The θPDF at a knee extension angle of 140 degrees were measured for 37 female post-pubertal volleyball players. Then, the players were assigned to either the flexible (n = 10) or inflexible (n = 14) groups according to earlier recommended criteria. Testing included the CMJ with and without an arm swing, and maximal knee extensions and flexions in 3 angular velocities on an isokinetic dynamometer. CMJ height performed with or without an arm swing (r(22) = 0.563, p = 0.040 and r(22) = 0.518, p = 0.009, respectively) and relative power (r(22) = 0.517, p = 0.010 and r(22) = 0.446, p = 0.030, respectively) were positively correlated with the extensors' torque at 180°/s and were negatively correlated with the flexibility level of the dominant side ankle (r(22) = -0.529, p = 0.008 and r(22) = -0.576, p = 0.030, respectively). A moderate positive correlation was also revealed between the CMJ height with and without an arm swing and the power of the non-dominant knee extensors (r(22) = 0.458, p = 0.024 and r(22) = 0.402, p = 0.049, respectively) and flexors (r(22) = 0.484, p = 0.016 and r(22) = 0.477, p = 0.018, respectively). Results of the 2 × 2 repeated ANOVA measurements revealed that flexible players jumped significantly (p < 0.05) higher during the CMJs, whilst there was a group effect only on the isokinetic knee extensor muscles' torque. In conclusion, a more flexible ankle joint and a higher isokinetic knee extensor's torque generating capacity resulted in higher CMJ performance. Therefore, ankle flexibility should be emphasized in training and is suggested to be included in preseason screening tests of youth female volleyball players.

Effects of a sprint and plyometric warm-up protocol on vertical jump height and power in adolescent fe-male volleyball players. A randomized crossover study

The purpose of this study was to compare the immediate effects of a plyometric warm-up protocol (PWU) and a sprint warm-up protocol (SWU) on jumping performance in female volleyball players aged 14-16 years. Through a cross-over experimental design, 18 female players were randomly divided into two groups, each receiving both warm-up protocols (PWU and SWU). Before and after each protocol, height and jumping power were evaluated in squat jump (SJ), countermovement jump (CMJ), and Abalakov (ABK) tests using the DM jump® contact mat. Both warm-up protocols significantly improved SJ, CMJ, and ABK performance (p&lt;.05), although mainly for jump height. The comparison between both warm-up protocols in the post-test showed no significant differences (p&gt;.05), although the greatest percentage increase in jump height and power was obtained with the SWU. The ANOVA showed significant differences in group 1 (initially assigned to PWU) for all tests except for CMJ and ABK power. In group 2 (initially assigned to SWU), the ANOVA also showed significant differences, except for SJ and CMJ power. It is concluded that both warm-up protocols improve jump height and power; however, SWU shows a more favorable trend than PWU. From a practical perspective, the preliminary findings of this pilot study can provide useful guidelines for the warm-up process; however, further randomized controlled studies with adequate statistical power are required for more robust conclusions. Keywords: warm-up exercise, volleyball, muscle strength, athletic performance, adolescent

Effects of Plyometric Training on Sonographic Characteristics of Quadriceps Muscle and Patellar Tendon, Quadriceps Strength, and Jump Height in Adolescent Female Volleyball Players

The aim of this study was to investigate the effects of plyometric training on vastus lateralis (VL) and patellar tendon size, quadriceps isokinetic strength, and vertical jump height in adolescent female volleyball players. Thirty players (age mean ± SD: 15.7 ± 1.1 years) participated in a 6-week Sportsmetrics™ plyometric training program. VL thickness, echo intensity, and patellar tendon cross-sectional area were assessed by real-time ultrasound. Isokinetic quadriceps strength and vertical jump were assessed. The VL thickness, quadriceps strength, and VJ height increased and VL–echo intensity decreased after training. We recommended that 6-week Sportmetrics plyometric training program may be implemented in adolescent female volleyball programs especially before the beginning of the volleyball season.

Characteristics of Shoulder and Trunk Mobility of Adolescent Female Volleyball Players

&lt;p&gt;目的 : 反覆的過肩動作容易導致運動員肩關節外轉角度增加、內轉角度減少、及前側關節囊鬆弛，進而導致肩部傷害，本研究目的是比較青少年女性排球選手慣用手及非慣用手肩部與軀幹活動度差異。方法 : 共 16位高中女性排球選手參與,使用關節角度計評估慣用側與非慣用側的肩部及軀幹活動度，並計算肩內外轉全距、肩內/外轉兩側差異百分比、同側的肩內/外轉角度差異百分比、以及內轉角度缺損差異角度。以相依樣本 t 考驗分析參與者兩側之肩部活動度及軀幹活動度差異。結果 : 比較高中女性排球運動員的兩側肩關節活動度表現，僅在肩外轉角度項目，慣用側顯著大於非慣用側 ( p &lt; .05 )，其餘項目則未達顯著水準。另外，軀幹右轉與左轉活動度亦無顯著差異。慣用側與非慣用側的兩側差異百分比在內轉角度差異值達 14.30 &amp;plusmn; 27.18 %，在外轉角度差異值達 -9.01 &amp;plusmn; 12.54 %;同側內外轉角度差異百分比在慣用側達 31.73 &amp;plusmn; 39.69 %，在非慣用側達 6.06 &amp;plusmn; 30.08 %。結論 : 結果發現青少年女性排球選手在慣用側肩外轉角度明顯大於非慣用側，顯示健康選手在慣用側使用上已產生關節角度及軟組織適應的情形，軀幹活動度則無代償狀況發生，建議加強肩關節後側伸展，以及強化肩部肌力。&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;&lt;p&gt;Purpose: Repeated overhead movement could lead to an increase in external angle and decrease in internal angle of shoulder, and relaxation of anterior capsule, which may cause shoulder injuries. The purpose of this study is to compare the shoulder and trunk mobility of dominant and non-dominant side of the adolescent female volleyball players. Methods: 16 high school female volleyball players engage in this study. The range of motion of the shoulder and trunk of the dominant side and the non-dominant side was evaluated by using the joint goniometer, and the total range of shoulder rotation, the percentage of differences of internal and external rotation angle between dominant and non-dominant side, the percentage of difference between internal and external angle of same side, and the deficit of internal rotation angle was calculated. Dependent-samples t-test was used to analyze the difference of shoulder and trunk mobility between two sides. Results: Comparing the shoulder mobility of both limbs in high school female volleyball players, it was found that only in the angle of external rotation of dominant side was significantly larger than the non-dominant side, with no other differences between two sides. In addition, there was no significant difference in the range of motion of trunk rotation. The difference at internal rotation angle between two sides was 14.30 &amp;plusmn; 27.18 %, at external rotation angle was -9.01 &amp;plusmn; 12.54 %. The differences between internal and external rotation angle at the dominant side was 31.73 &amp;plusmn; 39.69 %, and at the non-dominant side was 6.06 &amp;plusmn; 30.08 %. Conclusions: The results showed that the external rotation angle of the shoulders on the dominant side of adolescent female volleyball players was significantly greater than that on the non-dominant side. It shows that healthy athletes have produced joint angles and soft tissue adaptations on the dominant side, while the range of motion of the trunk has no compensation. It is recommended to stretch the back of the shoulder joint and strengthen the shoulder muscles.&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;

Investigation Of Glenohumeral Internal Rotation Deficit Tendency of Adolescent Female Volleyball Players During Passive and Dynamic Movements

Investigation Of Glenohumeral Internal Rotation Deficit Tendency of Adolescent Female Volleyball Players During Passive and Dynamic Movements

Concurrent Validity of Movement Screening Criteria Designed to Identify Injury Risk Factors in Adolescent Female Volleyball Players.

Anterior cruciate ligament (ACL) injuries in female adolescent athletes occur at disproportionately high levels compared to their male counterparts. However, limited prospective data exist on the validity of low-cost screening tools that can proactively identify ACL injury risk, specifically for female athletes. The purpose of this study was to assess the concurrent validity of a three-task injury risk factor assessment by comparing visually derived outcome scores from two-dimensional (2D) video data with dichotomized three-dimensional (3D) biomechanical variables collected using motion capture technology. A total of 41 female club volleyball athletes (14.7 ± 1.4 years) were tested and asked to perform three tasks: double-leg vertical jump (DLVJ), single-leg squat (SLS), and single-leg drop landing (SLDL). One rater was trained on the scoring criteria for the 2D data and independently scored one forward-facing and one side-facing video for each task. Risk factors identified included poor knee position, lateral trunk lean, and excessive trunk flexion/extension. In addition, 3D joint angles were calculated for the trunk and knee in the sagittal and frontal planes and converted to dichotomous variables based on biomechanical thresholds of injury risk. For comparison of 2D and 3D outcomes, percent agreement and Cohen's kappa were calculated for each risk factor individually. Overall, 2D scores were found to exhibit moderate to excellent percent agreement with 3D outcomes for trunk position (69.1–97.1%). Specifically, ipsilateral trunk lean during single-leg tasks exhibited the highest agreement (85.3–88.2%) with moderate reliability (κ = 0.452–0.465). In addition, moderate to substantial reliability was found for trunk flexion during double-leg tasks (κ = 0.521–0.653); however, an evaluation of single-leg tasks resulted in only fair reliability (κ = 0.354). Furthermore, 2D scores were not successful in identifying poor knee position as percent agreement fell below 50% for both the single-leg tasks and averaged 60% agreement across both the phases of the DLVJ. Kappa coefficients further emphasized these trends indicating no to slight concurrent validity (κ = −0.047–0.167) across tasks. Overall, these findings emphasize the potential for valid, low-cost screening tools that can identify high-risk movement patterns. Further study is needed to develop improved assessment guidelines that may be employed through visual assessment in sports environments.

Influence of Maturity Status on Kinanthropometric and Physical Fitness Variables in Adolescent Female Volleyball Players

The aim of this research was to analyze differences in kinanthropometric characteristics and physical performance in relation to maturity status, as well as to determine if age, maturity offset or kinanthropometric variables could predict better performance in physical fitness tests. A total of 152 female volleyball players (14.16 ± 1.25 years old) underwent a kinanthropometric assessment, followed by a physical fitness assessment composed of different tests. The age at peak height velocity (APHV) was calculated, and the sample was divided according to biological maturation into three groups. Significant differences were observed in kinanthropometric variables (p &lt; 0.001–0.026), with early maturers showing higher values. Age, body mass, Cormic index, relative arm span, ∑8 skinfolds, fat mass, corrected arm and thigh girths, muscle mass and biacromial and biiliocristal breadths were the variables that best predicted performance in the physical tests (p &lt; 0.001–0.024). The more mature players showed higher values in most of the kinanthropometric variables, with the more remarkable differences being in body mass, height, arm span and sitting height, and those related to adiposity and absolute body composition, and with structural variables being the most influential on the physical tests. Age had a determinant influence on the differences found between groups in strength and power-related test performance.

An Off-season Plyometric and Resistance Training Programme to Improve Vertical Jump Height in Adolescent Female Volleyball Players

Plyometric training has shown to improve vertical jump height, but the design and implementation of a plyometric training programme for adolescents requires consideration of several variables as well as the time of the season. The purpose of this study was to implement a pragmatic programme that improves vertical jump height, and to monitor the effects of a 15 week off-season plyometric and resistance training programme on the vertical jump height in adolescent female volleyball players. Ten adolescent female volleyball players (age: 15.1 ± 0.9 years, height: 1.71 ± 0.04 m, body mass: 63.6 ± 6.0 kg, volleyball training experience: 5.1 ± 1.4 years) underwent 15 weeks of plyometric and resistance training (twice and once a week, respectively). A single-targeted block periodised approach and a linear periodisation model were applied. Vertical jump height was assessed before the programme (T1), after 4 weeks (T2), after 12 weeks (T3) and at the end of the programme (T4). Jump height significantly increased by 8.8% over the full time of the investigation. No significant difference was found between T1 and T2 but for all other pairwise comparisons. Similarly, leg power was observed to increase by 6.5% (P = 0.001). The 15-weeks training programme showed to improve jump height and leg power. In consideration of its practical nature and its results in comparison with similar intervention studies, the programme suggests practical relevance for coaches.

Changes In Isokinetic Muscle Strength Of The Knee In Elite Female Adolescent Volleyball Players

There are few reports regarding changes in joint muscle strength in elite-level adolescent athletes after systematic training. PURPOSE: This study followed elite-level adolescent female volleyball players for 4 years to analyze changes in knee joint muscle strength after systematic training. METHODS: We performed isokinetic muscle strength testing of the knee at angular velocities of 60°/s and 240°/s in 16 elite-level adolescent female volleyball players. RESULTS: Compared with baseline, in adulthood (4 years later), peak torque (240°/s) in the right flexor and extensor increased by 13.94% (78.38 ± 8.87 vs 89.31 ± 13.26 Nm, p = 0.029) and 16.02% (134.19 ± 20.38 vs 155.69 ± 24.80 Nm, p = 0.034), but the increase was not statistically significant for the left knee (p > 0.05). Left and right flexor endurance ratios increased by 17.00% (0.59 ± 0.13 vs 0.69 ± 0.12, p = 0.041) and 14.75%(0.61 ± 0.12 vs 0.70 ± 0.13 Nm, p = 0.037), respectively. The difference between bilateral homonymous muscles was more than 15%, in adolescence, at 60°/s, n = 1 for flexors, n = 5 for extensors; at 240°/s, n = 2 for flexors, n = 4 for extensors and in adulthood, at 60°/s, n = 1 for flexors, n = 2 for extensors; at 240°/s n = 1 case for flexors, n = 3 for extensors. CONCLUSION: After 4 years of systematic training, elite-level adolescent female volleyball players had significant increased (240°/s) peak torque for the dominant knee, and the endurance ratio of bilateral flexor muscles was improved. We recommend strengthening the knee flexor muscle group during training to increase hamstrings-to-quadriceps ratio values and reduce the risk of knee injury.

Muscle Architectural and Functional Adaptations Following 12-Weeks of Stretching in Adolescent Female Athletes.

This study examined the effects of high-volume static stretching training on gastrocnemius muscle architecture, ankle angle and jump height in 21 female adolescent volleyball players. Static stretching of the plantar flexors of one leg (STR) was performed five times/week for 12 weeks, in addition to volleyball training, with the contra-lateral leg used as control (CON). Total duration of stretching per session increased from 540 s (week 1) to 900 s (week 12). At baseline, week 12 and after 3 weeks of detraining, muscle architecture at the middle and the distal part of both gastrocnemius heads (medialis and lateralis) and ankle angle were examined at rest and at maximum dorsiflexion. At the same time-points gastrocnemius cross-sectional area (CSA) was also assessed, while jumping height was measured at baseline and week 12. Following intervention, ankle dorsiflexion increased in both legs with a greater increase in STR than CON (22 ± 20% vs. 8 ± 17%, p < 0.001). Fascicle length at the middle part of gastrocnemius medialis increased only in the STR, at rest (6 ± 7%, p = 0.006) and at maximum dorsiflexion (11 ± 7%, p < 0.001). Fascicle length at maximum dorsiflexion also increased at the distal part of gastrocnemius lateralis of STR (15 ± 13%, p < 0.001). A greater increase in CSA (23 ± 14% vs. 13 ± 14%, p < 0.001) and in one-leg jumping height (27 ± 30% vs. 17 ± 23%, p < 0.001) was found in STR than CON. Changes in ankle angle, fascicle length and CSA were maintained following detraining. High-volume stretching training for 12 weeks results in ankle dorsiflexion, fascicle length and muscle cross sectional area increases in adolescent female volleyball players. These adaptations may partly explain improvements in jump performance.

The Ankle Joint Range of Motion and Its Effect on Squat Jump Performance with and without Arm Swing in Adolescent Female Volleyball Players

A flexible ankle joint is suggested to be a contributing factor for vertical squat jump (SQJ) performance. The purpose of the study was to investigate the effect of the active (ACT) and passive (PAS) ankle joint range of motion (ROM) on SQJ performed by adolescent female volleyball players. ACT and PAS ankle ROM at knee extension angles of 90, 140, and 180 degrees (180 degrees: full extension) were measured with a video analysis method for 35 female post-pubertal volleyball players (16.3 ± 1.1 yrs, 1.80 ± 0.04 m, 68.8 ± 6.8 kg). Additionally, the players fulfilling previously recommended criteria were assigned to the flexible (n = 10) and inflexible (n = 8) groups and executed SQJ with and without an arm swing on a force-plate. Results of the 2 × 2 × 3 MANOVA revealed a significant (p < 0.05) flexibility type and knee angle effect, as ankle ROM was larger in PAS compared to ACT and as the knee joint progressed from 90 to 180 degrees extension. The 2 × 2 ANOVA revealed a significant (p < 0.05) group effect, as flexible players jumped higher in the arm swing SQJ, along with a significant arm swing effect on key SQJ kinetic parameters. In conclusion, a more flexible ankle joint result in improved SQJ performance. Therefore, ankle flexibility training should be implemented in youth volleyball players.

Functional movement screen proficiency of adolescent female volleyball players

Assessments and testing of young athletes often exclude the fundamental and functional movement capacity, which are critical for healthy motor development of adolescents. The aim of this study was to evaluate functional capacity of young female volleyball players and determine if participation in volleyball leads to development of movement dysfunctions. Two-hundred fifty-eight (258) adolescent female volleyball players (14.3 ± 1.7 yrs) underwent the functional movement screen. Person correlation showed no significant relationship between functional tests and playing experience, while age showed significant, but weak relationship with total functional score (r = 0.189; p &lt; 0.005). Overall, 44% of participants scored less than 14. Paired sample t-tests show significant bilateral asymmetries in hurdle step, in-line lunge, and shoulder mobility tests. Functional movement screen was useful in identifying functional limitations and asymmetries in young female athletes. However, as neither age nor playing experience were strongly associated with functional score, more attention should be given to the qualitative movement assessment of individual tests, rather than the composite score.

Does the Weighted Rope Jump Training Affect the Motor Skills in Adolescent Female Volleyball Players?

The aim of this study was to investigate the effect of a 12-week rope jumping and weighted rope jumping exercise programme on body composition and strength performance in 25 female adolescent volleyball players. Group 1 was trained on the weighted rope jumping (WRJ; (n=8)) diet as well as volleyball training, Group 2 on rope jumping (RJ; (n=9)) diet as well as volleyball training and Group 3, the control (C; (n=8)), participated only volleyball training.

Effects of Weighted Versus Standard Jump Rope Training on Physical Fitness in Adolescent Female Volleyball Players: A Randomized Controlled Trial

Purpose: The aim of this study was to compare the effects of 12-week standard versus weighted jump rope training on physical fitness tests including anaerobic power, speed, agility and flexibility in female adolescent volleyball players. Methods: Twenty-five female volleyball players were recruited to the study. Participants were randomly separated into three study groups; weighted jump rope training (n=8), standard jump rope training (n=9) and control group (n=8). All participants were assessed at baseline and after 12-week training. Physical fitness was measured by using vertical jump test, 30-meter sprint test, hexagonal obstacle test, zigzag test and sit and reach test. Repeated-measures ANOVA was used for statistical analysis. Results: Comparisons showed that after 12-week training, weighted jump-rope training resulted in higher improvements in anaerobic power (p=0.03) and agility (p=0.003) when compared to control training; and higher improvement in agility when compared to standard jump rope training (p=0.001). In addition, at the end of training, speed and flexibility gains were similar in all groups (p>0.05). Discussion: Weighted jump rope training resulted in higher improvements of anaerobic power and agility in female adolescent volleyball players. The findings of the study provide basic knowledge for developing training protocols for adolescent volleyball players.

Concurrent agreement between an anthropometric model to predict thigh volume and dual-energy X-Ray absorptiometry assessment in female volleyball players aged 14-18 years.

BackgroundA variety of performance outputs are strongly determined by lower limbs volume and composition in children and adolescents. The current study aimed to examine the validity of thigh volume (TV) estimated by anthropometry in late adolescent female volleyball players. Dual-energy X-ray absorptiometry (DXA) measures were used as the reference method.MethodsTotal and regional body composition was assessed with a Lunar DPX NT/Pro/MD+/Duo/Bravo scanner in a cross-sectional sample of 42 Portuguese female volleyball players aged 14–18 years (165.2 ± 0.9 cm; 61.1 ± 1.4 kg). TV was estimated with the reference method (TV-DXA) and with the anthropometric method (TV-ANTH). Agreement between procedures was assessed with Deming regression. The analysis also considered a calibration of the anthropometric approach.ResultsThe equation that best predicted TV-DXA was: -0.899 + 0.876 × log10 (body mass) + 0.113 × log10 (TV-ANTH). This new model (NM) was validated using the predicted residual sum of squares (PRESS) method (R2 PRESS = 0.838). Correlation between the reference method and the NM was 0.934 (95%CI: 0.880–0.964, Sy∙x = 0.325 L).ConclusionsA new and accurate anthropometric method to estimate TV in adolescent female volleyball players was obtained from the equation of Jones and Pearson alongside with adjustments for body mass.Electronic supplementary materialThe online version of this article (doi:10.1186/s12887-016-0730-7) contains supplementary material, which is available to authorized users.

Perceived Teammate Acceptance and Sport Commitment in Adolescent Female Volleyball Players

Grounded in Scanlan’s sport commitment model (SCM), the purpose of this study was to explore the relationship between feelings of teammate acceptance and sport commitment in a sample of adolescent female volleyball players (N = 209). Despite theoretical justification for including social forms of influence such as social support and social acceptance as direct sources of sport commitment, empirical evidence has not been supportive of this association. Therefore, direct and indirect relationships between teammate acceptance and sport commitment within the SCM were tested. Findings supported the indirect relationship between teammate acceptance and sport commitment through sport enjoyment, personal investments, social constraints, and investment opportunities, accounting for 48% of the variance in sport commitment. It appears that teammate acceptance may be better situated as a distal source of sport commitment, but further research with more diverse samples is necessary. Sports psychologists who can collectively help athletes, coaches, and parents develop responsive interpersonal skills while reducing corporal punishment and aggression tactics can facilitate greater levels of social acceptance.