Edvin Dervišević

Vertical jumping tests in volleyball: reliability, validity, and playing-position specifics.

Abstract Sattler, T, Sekulic, D, Hadzic, V, Uljevic, O, and Dervisevic, E. Vertical jumping tests in volleyball: reliability, validity, and playing-position specifics. J Strength Cond Res 26(6): 1532–1538, 2012—Vertical jumping is known to be important in volleyball, and jumping performance tests are frequently studied for their reliability and validity. However, most studies concerning jumping in volleyball have dealt with standard rather than sport-specific jumping procedures and tests. The aims of this study, therefore, were (a) to determine the reliability and factorial validity of 2 volleyball-specific jumping tests, the block jump (BJ) test and the attack jump (AJ) test, relative to 2 frequently used and systematically validated jumping tests, the countermovement jump test and the squat jump test and (b) to establish volleyball position–specific differences in the jumping tests and simple anthropometric indices (body height [BH], body weight, and body mass index [BMI]). The BJ was performed from a defensive volleyball position, with the hands positioned in front of the chest. During an AJ, the players used a 2- to 3-step approach and performed a drop jump with an arm swing followed by a quick vertical jump. A total of 95 high-level volleyball players (all men) participated in this study. The reliability of the jumping tests ranged from 0.97 to 0.99 for Cronbachs alpha coefficients, from 0.93 to 0.97 for interitem correlation coefficients and from 2.1 to 2.8 for coefficients of variation. The highest reliability was found for the specific jumping tests. The factor analysis extracted one significant component, and all of the tests were highly intercorrelated. The analysis of variance with post hoc analysis showed significant differences between 5 playing positions in some of the jumping tests. In general, receivers had a greater jumping capacity, followed by libero players. The differences in jumping capacities should be emphasized vis-a-vis differences in the anthropometric measures of players, where middle hitters had higher BH and body weight, followed by opposite hitters and receivers, with no differences in the BMI between positions.

Risk factors for ankle sprain in volleyball players: A preliminary analysis

Injuries in volleyball are sport specific and occur around the net during spiking and blocking. The most common acute injury in volleyball is ankle sprain. There are limited data about the intrinsic risk factors for the ankle sprains in volleyball players. We investigated the influence of muscle strength, postural balance and active range of motion on the ankle sprain occurrence in volleyball players. In 38 professional volleyball players we have tested the strength of plantar and dorsal flexors using isokinetic dynamometer. Dynamic postural balance was measured using Biodex Balance System and active range of motion was tested by the means of universal goniometry. Following the testing players were prospectively followed up over a season, with injuries and exposure rates registered by the team coaches. Binary logistic regression was used to evaluate the role of individual risk factors. The main findings of our study indicate that higher strength of plantar flexors (odds ratio 1.22, 95% C.I. 1.04-1.43, p< 0.05) and decreasing range of motion in dorsiflexion (odds ratio 0.63, 95% C.I. 0.41-0.97) are significant risk factors for the ankle sprain. The results are suggesting that both risk factors are limiting the ability to land safely from a jump, and that plyometric exercises, proper landing technique and gastrocnemius stretching should be emphasized in the preventive training programs in volleyball players.

The isokinetic strength profile of quadriceps and hamstrings in elite volleyball players

Knowledge of lower-extremity strength can be used in injury prevention, conditioning and rehabilitation of volleyball players. The goals were: (1) to describe the bilateral concentric and eccentric quadriceps (Q) and hamstrings (H) muscle function in volleyball players, (2) to evaluate the differences in Q and H strength, strength ratios and bilateral strength asymmetry among age groups, playing positions and playing levels, (3) to compare bilateral strength asymmetry in Q and H muscles in two different contraction modes. Ninety five professional male volleyball players were tested on an isokinetic machine at 60 ◦ /s to assess concentric and eccentric Q and H strength. We also calculated strength ratios and bilateral strength asymmetries. MANOVAs indicated significant main effect of playing level on relative PT (p = 0.001) and strength ratios ( p< 0.05). International-level players had significantly ( p< 0.05) higher H strength and dynamic control ratio (DCR) of the right leg compared to the 1st and/or 2nd national division players. There were no signs of bilateral strength asymmetry regardless of muscle group tested and contraction mode. Our results suggest that right H strength and DCR could be important for successful volleyball performance. Descriptive data about Q and H muscle function can be used as guidelines for coaches and therapists during training and rehabilitation of male volleyball players.

Strength asymmetry of the shoulders in elite volleyball players.

CONTEXT Volleyball players are reported to have shoulder strength imbalances. Previous authors have primarily investigated small samples of male players at a single skill level, without considering playing position, and with inconsistent findings. OBJECTIVE To evaluate shoulder strength asymmetry and a history of shoulder injury in a large sample of professional volleyball players of both sexes across different playing positions and skill levels. DESIGN Descriptive laboratory study. PATIENTS OR OTHER PARTICIPANTS A sample of 183 volleyball players (99 men, 84 women). MAIN OUTCOME MEASURE(S) We assessed shoulder internal-rotator and external-rotator concentric strength at 60°/s using an isokinetic dynamometer and dominant-nondominant differences in shoulder strength and strength ratios using repeated-measures analyses of variance. Peak torque was normalized for body mass and external-rotation/internal-rotation concentric strength. RESULTS Internal-rotation strength was asymmetric in favor of the dominant side in both sexes, regardless of previous shoulder injury status. Male volleyball players had a lower shoulder strength ratio on the dominant side, regardless of previous shoulder injury status. However, this finding was valid only when hand dominance was taken into account. Female volleyball players playing at a higher level (ie, first versus second division) were 3.43 times more likely to have an abnormal strength ratio. Playing position was not associated with an abnormal shoulder strength ratio or strength asymmetry. CONCLUSIONS In male volleyball players, the external-rotation/internal-rotation strength ratio of the dominant shoulder was lower, regardless of playing position, skill level, or a previous shoulder injury. In female players, the ratio was less only in those at a higher skill level. Although speculative, these findings generally suggest that female volleyball players could have a lower risk of developing shoulder-related problems than male volleyball players. Isokinetic shoulder testing may reveal important information about the possible risk factors for shoulder injuries, so we recommend including it in the functional screening of volleyball players.

Quadriceps and hamstrings strength in team sports: Basketball, football and volleyball

Isokinetic strength evaluation of the quadriceps (Q) and hamstrings (H), in both concentric (con) and eccentric (ecc) mode of contraction, is an important part of the comprehensive evaluation and rehabilitation of athletes. Systematic preseason isokinetic evaluation of the knee is very useful in highlighting the athletes at risk for those injuries as well as for the optimization of the training process. The main purpose of this short review was to present the major findings of studies relating to this issue.

Vertical jump performance of professional male and female volleyball players: effects of playing position and competition level.

Abstract Sattler, T, Hadžić, V, Dervišević, E, and Markovic, G. Vertical jump performance of professional male and female volleyball players: effects of playing position and competition level. J Strength Cond Res 29(6): 1486–1493, 2015—Vertical jump (VJ) performance is an important element for successful volleyball practice. The aims of the study were (a) to explore the overall VJ performance of elite volleyball players of both sexes, (b) to explore the differences in VJ performance among different competition levels and different playing positions, and (c) to evaluate the sex-related differences in the role of the arm swing and 3-step approach with arm swing on the jump height. We assessed the VJ capacity in 253 volleyball players (113 males and 140 females) from Slovenian first and second Volleyball Division. The height of squat jump (SJ), countermovement jump, block jump, and attack jump was tested using an Optojump system. We observed significant differences (p ⩽ 0.05) in VJ height between different levels of play that were most pronounced in the SJ. Position-related differences in VJ performance were observed in male players between receivers and setters (p ⩽ 0.05), whereas in females, VJ performance across different playing positions seems equal. Finally, we found that male players significantly better use the arm swing during VJ than females (p ⩽ 0.05), whereas the use of eccentric part of the jump and approach before the spike to improve VJ performance seem to be equally mastered activity in both sexes. These results could assist coaches in the development of jumping performance in volleyball players. Furthermore, presented normative data for jump heights of elite male and female volleyball players could be useful in selection and profiling of young volleyball players.