The relative age effect (RAE) on human performance has been well studied in many sports, especially in soccer; however, little information has been available about the prevalence of RAE in ...volleyball, and its role on anthropometric and physiological characteristics. The aim of the present study was to examine (a) the prevalence of RAE in selected (i.e., to be considered for the national team) and non-selected youth female volleyball players, and (b) the relationship of birth quarter (BQ) with anthropometric and physiological characteristics. Selected (
= 72, age 13.3 ± 0.7 years, weight 62.0 ± 7.2 kg, height 1.72 ± 0.06 m) and non-selected female volleyball players (
= 53, age 13.9 ± 1.1 years, weight 56.4 ± 7.3 kg, height 1.66 ± 0.06 m) performed a series of anthropometric and physiological tests. Twenty-six selected participants were born in the first quarter of the year, 19 in the second, 14 in the third, and 13 in the forth. The corresponding frequency by BQ in non-selected participants was 12, 12, 17, and 12. No association was observed between the number of participants and their frequency by BQ neither in the selected (
= 2.79,
= 0.425) nor in the non-selected group (
= 0.64,
= 0.886). Anthropometric and physiological characteristics did not vary by BQ (
> 0.05). The absence of RAE in female volleyball players and the similarities of anthropometric and physiological characteristics among BQ might be due to technical-tactical character of this sport. These findings would be of great practical value for coaches and fitness trainers working with young volleyball players.
This study aimed to review the current evidence on the independent and combined effects of diet and exercise and their impact on skeletal muscle mass in the elderly population. Skeletal muscle makes ...up approximately 40% of total body weight and is essential for performing daily activities. The combination of exercise and diet is known to be a potent anabolic stimulus through stimulation of muscle protein synthesis from amino acids. Aging is strongly associated with a generalized deterioration of physiological function, including a progressive reduction in skeletal muscle mass and strength, which in turn leads to a gradual functional impairment and an increased rate of disability resulting in falls, frailty, or even death. The term sarcopenia, which is an age-related syndrome, is primarily used to describe the gradual and generalized loss of skeletal muscle mass (mainly in type II muscle fibers) and function. Multimodal training is emerging as a popular training method that combines a wide range of physical dimensions. On the other hand, nutrition and especially protein intake provide amino acids, which are essential for muscle protein synthesis. According to ESPEN, protein intake in older people should be at least 1 g/kgbw/day. Essential amino acids, such as leucine, arginine, cysteine, and glutamine, are of particular importance for the regulation of muscle protein synthesis. For instance, a leucine intake of 3 g administered alongside each main meal has been suggested to prevent muscle loss in the elderly. In addition, studies have shown that vitamin D and other micronutrients can have a protective role and may modulate muscle growth; nevertheless, further research is needed to validate these claims. Resistance-based exercise combined with a higher intake of dietary protein, amino acids, and/or vitamin D are currently recognized as the most effective interventions to promote skeletal muscle growth. However, the results are quite controversial and contradictory, which could be explained by the high heterogeneity among studies. It is therefore necessary to further assess the impact of each individual exercise and nutritional approach, particularly protein and amino acids, on human muscle turnover so that more efficient strategies can be implemented for the augmentation of muscle mass in the elderly.
The purpose of this study was to analyse selected serve characteristics in top-level male volleyball, with a special focus on detecting adaptations of the serve skill among seasons. The indicators ...examined were type, position, direction and quality of serve. The sample consisted of 5482 serves from three final phases of different top-level tournaments (Olympic Games 2012, N = 1942, World League 2017, N = 1883, World Championship 2018, N = 1657). The interrelationships between variables were analyzed using chi-squared tests, log-linear modelling and multiple correspondence analysis. The results showed that the interaction of all serve indicators are statistically important, but the combination of the variables’ categories that were more responsible for association alternated across the seasons under study. A 3-way association term was revealed for season 2012 (type/position/direction) and 2018 (type/position/quality), while for season 2017 multiple 2-way interactions were found (type/position, type/direction, position/quality, direction/quality). The direction of the serve to the horizontal axis of the court was correlated to the quality of serve and consequently with the advantage of the serving team, while a more tactical perspective for serve skill is formed over periods in top level male volleyball.
Postural control and muscle strength are important factors for the performance of everyday activities and reduce the possibility of fall-related injuries. The purpose of this study was to investigate ...the efficacy of a balance training program using action songs on balance and strength of preschool children. A total of 51 preschool children were randomly divided into an intervention group (25 children) and a control group (26 children). The intervention group received a balance training program with action songs (six weeks, two times a week, total 12 sessions), while the control group followed the normal curriculum. Prior to and after the intervention, both groups were assessed in dynamic balance (walking on balance beams), static balance (single-leg stance on forceplate and Flamingo test) and strength (long jump and handgrip). The results showed that the intervention group performed significantly better in the dynamic balance and Flamingo test. There were no significant differences in the centre of pressure (CoP) displacement in the Medio-Lateral direction (CoP/ML), the Anterio-Posterior (CoP/AP), and the strength variables. The reliability of the single-leg test on the forceplate was moderate. Moreover, there were no correlations between balance and muscle strength variables. It can be concluded that the balance training program with action songs constitutes an effective activity for developing preschool children’s balance, but not strength. Perhaps balance and muscle strength are independent of each other and may have to be trained with complementary activities. Moreover, the results of the study and the behaviour of the children during the one-leg stance test on the forceplate gave rise to questions regarding the appropriateness of this test for preschool children.
Postural control and muscle strength are important factors for the performance of everyday activities and reduce the possibility of fall-related injuries. The purpose of this study was to investigate the efficacy of a balance training program using action songs on balance and strength of preschool children. A total of 51 preschool children were randomly divided into an intervention group (25 children) and a control group (26 children). The intervention group received a balance training program with action songs (six weeks, two times a week, total 12 sessions), while the control group followed the normal curriculum. Prior to and after the intervention, both groups were assessed in dynamic balance (walking on balance beams), static balance (single-leg stance on forceplate and Flamingo test) and strength (long jump and handgrip). The results showed that the intervention group performed significantly better in the dynamic balance and Flamingo test. There were no significant differences in the centre of pressure (CoP) displacement in the Medio-Lateral direction (CoP/ML), the Anterio-Posterior (CoP/AP), and the strength variables. The reliability of the single-leg test on the forceplate was moderate. Moreover, there were no correlations between balance and muscle strength variables. It can be concluded that the balance training program with action songs constitutes an effective activity for developing preschool children’s balance, but not strength. Perhaps balance and muscle strength are independent of each other and may have to be trained with complementary activities. Moreover, the results of the study and the behaviour of the children during the one-leg stance test on the forceplate gave rise to questions regarding the appropriateness of this test for preschool children.
: Maximal heart rate (HR
) is an important training and testing tool, especially in the context of evaluating intensity in exercise prescription; however, few studies have examined the validity of ...prediction equations of HR
in physically active female adolescents and the role of maturation level. Therefore, the aim of the present study was to examine the differences between measured and predicted HR
in a sample of physically active female adolescents.
: Seventy-one selected volleyball players (age 13.3 ± 0.7 years, body mass 62.0 ± 7.2 kg, height 1.72 ± 0.06 m) performed a 20 m shuttle run endurance test, and the actual HR
was compared with Tanaka HR
('208 - 0.7 × age') and Fox HR
('220 - age').
: A large main effect of assessment method on HR
was found (
< 0.001,
= 0.486) with Fox overestimating actual HR
by 6.8 bpm (95% confidence intervals, CI; 4.2, 9.3) and Tanaka underestimating actual HR
by -2.6 bpm (95% CI; -5.1, -0.1). The more matured participants had similar actual HR
(mean difference -2.4 bpm; 95% CI; -6.5, 1.7;
= 0.242, d = -0.28), difference Fox - actual HR
(1.5 bpm; 95% CI; -2.6, 5.6,
= 0.466, d = 0.17), and difference Tanaka - actual HR
(1.7 bpm; 95% CI; -2.4, 5.8;
= 0.414, d = 0.19) to the less matured participants.
: These findings suggest that age-based prediction equations of HR
developed in adult populations should be applied with caution in physically active female adolescents, and Tanaka should be preferred instead of the Fox equation.
The aim of the present trial was to investigate the effect of two stretching programs, a dynamic and a static one, on the sprint ability of recreational volleyball players. The sample consisted of 27 ...male recreational volleyball players (age 21.6 ± 2.1 years, mean ± standard deviation, body mass 80.3 ± 8.9 kg, height 1.82 ± 0.06 m, body mass index 24.3 ± 2.5 kg.m
, volleyball experience 7.7 ± 2.9 years). Participants were randomly divided into three groups: (a) the first performing dynamic stretching exercises three times per week, (b) the second following a static stretching protocol on the same frequency, and (c) the third being the control group, abstaining from any stretching protocol. The duration of the stretching exercise intervention period was 6 weeks, with all groups performing baseline and final field sprinting tests at 4.5 and 9 m. The post-test sprint times were faster in both the 4.5 (
= 0.027, η
= 0.188) and 9 m tests (
< 0.001, η
= 0.605) compared to the pre-test values. A large time × group interaction was shown in both the 4.5 (
= 0.007, η
= 0.341) and 9 m tests (
= 0.004, η
= 0.363) with the static and dynamic stretching groups being faster in the post-test than in the pre-test, whereas no change was found in the control group. The percentage change in the 4.5 m sprint time correlated with volleyball experience (
= -0.38,
= 0.050), i.e., the longer the volleyball experience, the larger the improvement in the 4.5 m sprint. Thus, it is concluded that both stretching techniques have a positive effect on the velocity of recreational male volleyball players, when performed at a frequency of three times per week for 6 weeks under the same conditions as defined in the study protocol.
The aim of the present study was to examine subcutaneous adipose tissue distribution in female volleyball players with regards to (a) variation by anatomical site, (b) differences among age groups ...and playing positions, and (c) physiological characteristics associated with performance. Participants were adolescent (
= 89, age 15.6 ± 0.9 years, mean ± standard deviation) and adult female volleyball players (
= 78, 24.8 ± 5.3 years), who performed a series of anthropometric and performance tests including skinfold thickness in 10 sites, Abalakov jump (AJ) and handgrip test (HG). Chin had the smallest thickness, and iliac crest and abdomen the largest. The largest correlations of skinfold thickness were shown with regards to AJ ad HG. Coefficient of variations in skinfold thickness correlated with performance indices with small magnitude. Triceps and chin were the most frequent predictors of performance indices. The anatomical site of skinfold was near the active muscle groups related to performance in HG. In conclusion, performance indices such AJ and HG were related with thickness of specific skinfolds and with the variation of thickness by anatomical site (i.e., the less the variation, the better the performance). Considering the relevance of specific skinfolds (e.g., triceps and chin) for performance, their further use would be recommended for purposes of training monitoring, volleyball players' selection and talent identification.
The aim of the present study was to examine the variation in core stability and symmetry of youth female volleyball players by age, and its relationship with anthropometric characteristics, the 30 s ...Wingate anaerobic test (WAnT), and the 30 s Bosco test. Female volleyball players (n = 24, age 13.9 ± 1.9 years, mean ± standard deviation) performed a series of anthropometric, core stability tests (isometric muscle endurance of torso flexors, extensors, and right and left lateral bridge), WAnT (peak power, mean power, Pmean, and fatigue index, FI) and Bosco test (Pmean). Flexors-to-extensors ratio and right-to-left lateral bridge ratio were also calculated. Participants were grouped into younger (n = 12, 12.3 ± 1.2 years) or older than 14 years (n = 12, 15.4 ± 1.0 years), and into normal (flexors-to-extensors ratio < 1; n = 17) or abnormal flexors-to-extensors ratio (≥1; n = 7). The older age group was heavier (+11.3 kg, mean difference; 95% CI, 2.0, 20.6) and with higher body mass index (+2.8 kg m−2; 95% CI, 0.4, 5.1) than the younger age group. The group with abnormal flexors/extensors had larger flexors muscle endurance (+77.4 s; 95% CI, 41.8, 113.0) and higher flexors/extensors ratio (+0.85; 95% CI, 0.61, 1.10) than the normal group. Body fat percentage (BF) correlated moderately-to-largely with flexors (r = −0.44, p = 0.033), extensors (r = −0.51, p = 0.011), and left lateral bridge (r = −0.45, p = 0.027); WAnT Pmean moderately-to-largely with right (r = 0.46, p = 0.027) and left lateral bridge (r = 0.55, p = 0.006); FI moderately-to-largely with right (r = −0.45, p = 0.031) and left lateral bridge (r = −0.67, p < 0.001), and right/left ratio (r = 0.42, p = 0.046); Bosco Pmean correlated moderately-to-largely with right (r = 0.48, p = 0.020) and left lateral bridge (r = 0.67, p = 0.001). A stepwise regression analysis indicated FI and BF as the most frequent predictors of core stability. The findings of the present study suggested that increased core stability was related to decreased BF and increased anaerobic capacity. A potential misbalance between torso flexors and extensors might be attributed to bidirectional variations (either high or low scores) of flexors muscle endurance rather than decreased extensors muscle endurance.
The aim of this study was to investigate the effect of fatigue on electromyographic (EMG) parameters of healthy young adults during obstacle crossing of two different heights. Twelve untrained male ...adults (23 ± 5 years of age) were fatigued running on a treadmill with increasing speed and inclination and walked over an obstacle with a height set at 10% and 20% of each individual's lower limb length. Maximal plantar flexor torque and EMG of the medial gastrocnemius, soleus, and tibialis anterior muscles of the trailing limb were assessed during obstacle crossing. Data were captured before, immediately after and 5 minutes after a fatigue session. Fatigue induced significant reduction on the plantar flexor torque output immediately after and 5 minutes after exhaustion. After fatigue gait speed was not affected, the minimum distance between the obstacle and the trailing or leading foot remained unchanged, and the trailing foot contacted the ground closer to the obstacle immediately after fatigue. Regarding the EMG, medial gastrocnemius became after fatigue more active during swing phase when increasing the obstacle height, whereas this was not the case before or 5 minutes after fatigue. No other significant difference was observed for any of the examined muscles. It is concluded that the assessed fatigue protocol induced only minimal changes in the EMG activity of the examined muscles during obstacle crossing. Therefore, it is suggested that the neuromuscular system of healthy young individuals is able to respond to the decreased force capacity after fatigue during obstacle crossing of heights up to the 20% of the limb length. Key PointsExhaustion after running on a treadmill induces significant reduction in plantar flexion strength and changes in the positioning of the feet relative to the obstacle during obstacle crossing.EMG activity of the calf muscles of the trailing limb does not change significantly after fatigue during the stance phaseDuring swing phase, medial gastrocnemius EMG activity of the trailing limb increases after fatigue when obstacle height increases.These minor changes in EMG after fatigue, reveals that untrained, healthy, young subjects may compensate the deficit in muscular force due to fatigue when performing obstacle crossing.
The aim of this research was to analyse the impact of various game structures on score and time-related variables in elite volleyball. A total of 114 male matches and 76 female matches (38 matches ...for each tournament) were analysed in under-23 world championships. An observational design was implemented to measure match duration, points scored per match and set, set point differences, tournament phase, match balance, and set tendencies in various game structures (set to 21, to 25 or to 15 points) in male and female categories. Standardised differences in mean values showed that a 15-point set game structure led to shortest matches and smallest time variability in match duration, the largest number of points per match, and greatest equality in terms of set score differences in both the male and the female category. The use of various game structures in training may be useful to coaches and conditioning specialists when planning training schemes and sessions, by introducing different game structures to manage volume and intensity in training more effectively. These results may also be useful to local and/or national volleyball federations willing to attract new young players, to promote learning and to render volleyball a fun activity, by implementing S15 at initial stages. In addition, they could be useful to international federations or committees, so as to attract larger audiences and sponsors interested in more appealing matches with high levels of competitiveness and entertainment.
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