Strength Asymmetry of the Shoulders in Elite Volleyball Players

Abstract

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 608/s using an isokinetic dynamometer and dominant-nondominant differences in shoulder strength and strength ratios using repeatedmeasures 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 externalrotation/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.Key Words: isokinetic testing, muscle imbalances, injury prevention, muscle strength Key PointsMale volleyball players had a lower external-rotation/internal-rotation strength ratio of the dominant shoulder. Female volleyball players at a higher skill level were 2.5 times more likely to have abnormal strength ratios. When analyzing shoulder strength findings, we must consider hand dominance. Functional screening of volleyball players could include isokinetic testing.I sokinetic strength testing can play an important part in the comprehensive evaluation and rehabilitation of a patient with a shoulder injury. 1 Of all the muscle groups of the shoulder, evaluation of the shoulder external rotators (ERs) and internal rotators (IRs) is most informative because those muscle groups are responsible for dynamic stabilization of the glenohumeral joint. 2 One ...

Isokinetic Performance of Shoulder External and Internal Rotators in Adolescent Male Volleyball Athletes

“…When comparing IR and ER PT average value, IR muscles presented average values higher than the ER muscles at both assessed angular velocities. This is an expected result both for non-athletes [27] and for volleyball athletes [8,9,16,[18][19][20][21].…”

“…During ER analyses, only at the angular velocity of 180°/s were the PT average value of the NDL significantly lower than those of the DL. When comparing this data with other volleyball studies, at the 60°/s angular velocity [8,9,17,18,20], and at the 90°/s [21], no significant differences were demonstrated between the DL and the NDL with respect to PT average analyses. At the angular velocity of 60°/s, Wang and Cochrane [19] found significantly different PT averages between the limbs, however, the NDL demonstrated higher values than the DL.…”

“…However, a detailed assessment of biomechanics and muscle performance is fundamental in the evaluation, treatment and prevention of shoulder injuries in players. At present there is a lack of studies related to the evaluation of isokinetic parameters which could reveal important information about possible risk factors for shoulder injuries in volleyball players [9]. The well-established outcome parameter in isokinetic analyses is peak torque (PT) [10], and considering volleyball asymmetric movements of the shoulder, imbalances in PT values between the dominant (D) and non-dominant (ND) shoulders are expected.…”

Desempenho muscular isocinético dos ombros em atletas de rúgbi

“…Os resultados do presente estudo não demonstraram diferenças estatisticamente significativas na velocidade angular de 180º/s, entretanto a 60º/s o MD apresentou valores médios significativamente superiores ao do MND, tanto para a musculatura RE como da RI na análise do PT. Estudos isocinéticos com atletas de modalidades esportivas assimétricas, como voleibol [17,[19][20][21][22][23], handebol [24,25], tênis [26][27][28], basebol [29,30] e polo aquático [31] também demonstraram que o MD apresenta valores maiores de PT dos RE e/ou RI. A utilização preferencial de um dos membros durante os principais movimentos de uma determinada prática esportiva faz com que haja um aumento da força muscular desse membro.…”

The use of a sphygmomanometer to measure shoulder isometric strength: a validity and reliability study

“…Measurement of shoulder strength also allows for intervention program effectiveness to be evaluated and can be used to help screen athletes at risk of shoulder injury (1). Assessment of both dominant and non-dominant shoulder strength can provide an insight into specific regions of weakness in some sporting populations and assist in injury prevention (2).…”