Body weight changes and voluntary fluid intakes of beach volleyball players during an official tournament

The aim of this study was to calculate sweat rates (measured by weight changes), voluntary fluid intakes, and fluid balance of beach volleyball players during a tournament. Data was collected during the 3 days of the tournament for male players (n=47) age M=26.17 (S.D.=5.12) years old. Participants were weighed before the warm up and they reweighed immediately after the game. The differences in body weight were calculated in grams. The voluntary fluid intake of players during the game was also recorded by observers, whose inter and intra reliability were evaluated (inter r=.89 and intra reliability r=.93). Fifty matches took place with a M=42.2min duration per match. A wide individual variation appeared in fluid intake and sweat loss. The calculated average sweat rate, fluid intake rate and fluid balance of players during each match were M=1440ml, M=731ml and M=-0.8%, respectively. Air temperature ranged from 26 degrees to 38 degrees C (M=33.58 degrees C, S.D.=2.8) and humidity from 42% to 75% (M=56.04%, S.D.=8.7) and both were measured in each day of tournament, at the beginning and at the end of each game. Although players' dehydration (-0.8%) was of mild level, it was more or less the same as it was reported in other team sports studies. ANOVA did not prove differences between elite and non-elite athletes in sweat loss and fluid intake (p>.01). Sweat rate was associated only with humidity (r=.99, p<.01) and with fluid intake (r=.315, p<.05). The athletes should be aware of the great significance of fluids and to intake greater quantities in order to prevent weight loss and at the same time loss of vital elements that would cause their performance to decline.     

排球运动员赛前心理特征及其调控研究

采用问卷调查法、文献资料法、比较分析法等对福建省排球运动员较常出现缺乏自信心、比赛经验不足、易受外界因素干扰等等心理问题进行分析，并结合排球训练时间对心理训练的方法进行了研究和探讨，研究表明，具体可行有效的心理训练方法可以提高排球运动员的心理素质，为创造优异成绩奠定良好的心理基础。     

A valid and reliable method to measure jump‐specific training and competition load in elite volleyball players

Use of a commercially available wearable device to monitor jump load with elite volleyball players has become common practice. The purpose of this study was to evaluate the validity and reliability of this device, the Vert, to count jumps and measure jump height with professional volleyball players. Jump count accuracy was determined by comparing jumps recorded by the device to jumps observed through systematic video analysis of three practice sessions and two league matches performed by a men's professional volleyball team. Jumps performed by 14 players were each coded for time and jump type and individually matched to device recorded jumps. Jump height validity of the device was examined against reference standards as participants performed countermovement jumps on a force plate and volleyball‐specific jumps with a Vertec. The Vert device accurately counted 99.3% of the 3637 jumps performed during practice and match play. The device showed excellent jump height interdevice reliability for two devices placed in the same pouch during volleyball jumps (r  = .99, 95% CI 0.98‐0.99). The device had a minimum detectable change (MDC ) of 9.7 cm and overestimated jump height by an average of 5.5 cm (95% CI 4.5‐6.5) across all volleyball jumps. The Vert device demonstrates excellent accuracy counting volleyball‐specific jumps during training and competition. While the device is not recommended to measure maximal jumping ability when precision is needed, it provides an acceptable measure of on‐court jump height that can be used to monitor athlete jump load.     

Daily and weekly training load and wellness status in preparatory,regular and congested weeks: a season-long study in elite volleyball players

The study aimed to assess the changes in the perceived internal load and wellness status of volleyball players in preparatory, regular (i.e. uncongested), and congested weeks during a full season. Thirteen elite volleyball players were studied (237 training sessions and 37 official matches). Session-RPE, muscle soreness, stress, fatigue, sleep quality, and the Hooper Index were measured daily using questionnaires. Training sessions were classified based on the number of matches per week and the days before or after a match: preparatory (no match), regular (one match), and congested weeks (two or more matches). Pairwise comparisons found significantly greater session-RPE scores (p < 0.05) one day before the match (304.74 A.U.), in regular weeks than in congested weeks (204.40 A.U.). Matches during the congested weeks (364.71 A.U.) had significantly higher session-RPE scores (p < 0.05) than regular weeks (252.97 A.U.). Three days before the match involved significantly higher values of muscle soreness, fatigue, stress, and sleep quality than regular weeks. Match accumulation increased the session-RPE training load of the matches. This study provides insights into the training load and well-being status before competition, for training the day of competition, and after the competition.     

Choice of jumping strategy in two standard jumps,squat and countermovement jump-effect of training background or inherited preference?

Six male subjects, three professional ballet dancers and three elite volleyball players, performed maximal vertical jumps from 1) a static preparatory position (squat jump), 2) starting with a countermovement (countermovement jump) and 3) a specific jump for ballet and for volleyball, respectively. The jumps were recorded on highspeed film (500 Hz) combined with registration of ground reaction forces, and net joint moments were calculated by inverse dynamics. The purpose was to investigate the choice of strategy in two standard jumps, squat jump and countermovement jump. The volleyball jump was performed with a sequential strategy and the ballet jump was performed with a simultaneous strategy. In the two standard jumps, the choice of strategy was individual and not related to training background. This was additionally confirmed in a test of seven ballet dancers and seven volleyball players.     

Strategies for the prevention of volleyball related injuries

Although the overall injury rate in volleyball and beach volleyball is relatively low compared with other team sports, injuries do occur in a discipline specific pattern. Epidemiological research has revealed that volleyball athletes are, in general, at greatest risk of acute ankle injuries and overuse conditions of the knee and shoulder. This structured review discusses both the known and suspected risk factors and potential strategies for preventing the most common volleyball related injuries: ankle sprains, patellar tendinopathy, and shoulder overuse.     

Prospective study of change in patellar tendon abnormality on imaging and pain over a volleyball season

Objective

Patellar tendon injury, defined by tendon abnormality (TA) on imaging and by pain, is common among volleyball players, but little is known about change in this injury over a volleyball season. Increased activity in the season compared with the off season may result in the development of TA and/or pain. This study investigated the behaviour of TA and pain over a competitive volleyball season.

Methods

Tendon abnormality and pain were measured in 101 volleyball players at the beginning and end of a season. Pain was measured with the single leg decline squat test, which loads the patellar tendon, and TA was detected with ultrasound imaging. Hours of weekly activity were measured and compared during the season and the off season. The proportion of tendons that underwent development and resolution in TA and/or pain over the season was investigated.

Results

Hours of weekly activity was greater during the season than in the off season. Most of the tendons investigated (66.3%) did not undergo a change in TA or pain over the season. Tendon abnormality and/or pain developed in 16.6% of tendons and resolved in 11.2%.

Conclusions

The tendons of volleyball players respond variably to the increased load over the season. Change in TA and pain does not appear to be entirely dependent upon load.     

Effect of a specific exercise strategy on strength and proprioception in volleyball players with infraspinatus muscle atrophy

Infraspinatus muscle atrophy is common in professional volleyball players, but it is unclear whether commonly observed strength and proprioception deficits can be reversed with training. Fifty‐four participants were recruited into an infraspinatus atrophy group (IAG , n = 18) and a non‐atrophy group (NAG , n = 18) of elite volleyballers plus a healthy non‐athletic control group (CG , n = 18). IAG were trained with a progressive, specific shoulder external rotator strengthening routine for 32 sessions over 8 weeks. Shoulder external rotation peak torque (SERPT ) and threshold to detect passive movement (TTDPM ) and joint position sense (JPS ) were measured before and after the intervention. At baseline, no significant difference was detected in strength or proprioception between the injured and control groups, but the normal athletes were stronger and had better proprioception than either IAG or CG (P  < .001). IAG (d  = 2.78) and NAG (d  = 0.442) improved strength significantly after training. IAG improved TTDM and JPS (P  < .001, d  = −0.719 and −2.942, respectively) but were still worse than NAG (P  < .001). Elite volleyball players with Infraspinatus muscle atrophy have strength and proprioception deficits which can be improved by a specific exercise program to normal but not elite athlete control levels.     

Does a drop landing represent a whole skill landing and is this moderated by fatigue?

This study aimed to determine whether the landing phase of a drop landing (DL) differed with respect to a complete jumping and landing task, a spike jump (SJ), and whether fatigue altered the landing of these movements. Fourteen male volleyball players performed five DL and SJ in a counterbalanced order under two experimental conditions: non‐fatigued and fatigued. Fatigue, induced by repetitive jumping sets, was confirmed by decrements in vertical jump height >25% and increased blood lactate >6 mmol/L. Each landing task was characterized by the resultant ground reaction forces (GRF), sagittal plane kinematics and muscle recruitment patterns of six lower extremity muscles. Two‐way repeated analysis of variance results indicated a main effect of movement on many of the GRF, kinematic and electromyographic variables characterizing landing, indicating that the two tasks required substantially different lower limb biomechanics during landing. Although fatigue did not alter the GRF in either task, there were significant movement × fatigue condition interactions. The significant between‐task differences in the biomechanical variables characterizing landing and the differential effects of fatigue on each landing task, question the validity of using a DL as an experimental task to investigate lower limb landing mechanics of whole jumping and landing movements.