Electromyography and nerve conduction velocity for the evaluation of the infraspinatus muscle and the suprascapular nerve in professional beach volleyball players.

BACKGROUND: Beach volleyball is an overhead sport with a high prevalence of infraspinatus muscle atrophy of the hitting shoulder. HYPOTHESIS: Infraspinatus muscle atrophy seems to be caused by a repetitive traction injury of the suprascapular nerve. Early pathological findings might be assessed with surface electromyography (EMG) and nerve conduction velocity (NCV) measurements. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Fully competitive professional beach volleyball players were assessed with a structured interview, shoulder examination, strength measurements (external rotation and elevation), and neurophysiological examination (surface EMG and NCV of the infraspinatus and supraspinatus muscles and the suprascapular nerve, respectively) during the Beach Volleyball Grand Slam tournament 2010 in Klagenfurt, Austria. RESULTS: Thirty-five men with an average age of 28 years were examined. Visible infraspinatus atrophy was found in 12 players (34%), of which 8 (23%) had slight atrophy and 4 (11%) had severe atrophy. External rotation (90%; P < .006) and elevation strength (93%; P = .03) were significantly lower in the hitting shoulder. Electromyography revealed a higher activation pattern in the infraspinatus muscle of the hitting arm in players with no or slight atrophy (P = .001) but a significantly lower activation pattern in players with severe atrophy (P = .013). Nerve conduction velocity measurements showed a significant higher latency and lower amplitude in the hitting shoulder of the total study group and the subgroup with infraspinatus atrophy. CONCLUSION: Professional beach volleyball players have a high frequency of infraspinatus atrophy (34%) and significantly reduced shoulder strength of the hitting shoulder. These findings are not associated with demographic factors. Electromyography and NCV measurements suggest a suprascapular nerve involvement caused by repetitive strain injuries of the nerve. External rotation strength measurements and NCV measurements can detect a side-to-side difference early, while EMG may show compensation mechanisms for progressive damaging of the suprascapular nerve and, as a result, loss of infraspinatus muscle strength.

The shoulders of professional beach volleyball players: high prevalence of infraspinatus muscle atrophy.

BACKGROUND: Beach volleyball is an Olympic overhead sport. It is not well known which clinical and imaging findings are normal and which are associated with symptoms. HYPOTHESIS: There are typical clinical and imaging findings in the hitting shoulders of fully competitive professional beach volleyball players, as compared with their nonhitting shoulders. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: During the Beach Volleyball Grand Slam Tournament in Klagenfurt, Austria, 84 professional players (54 men, 30 women) underwent a questionnaire-based interview and a complete physical examination, including scoring and sonography of both shoulders. Twenty-nine players had shoulder MRIs. RESULTS: The mean age of the athletes was 28 years. Atrophy of the infraspinatus muscle was found in 30% of the hitting shoulders, and it was not typically recognized by the players. The absolute Constant score was significantly lower in the hitting shoulder (87 versus 93 points, P < .0001). Average external rotation strength was decreased in the hitting shoulder (8.2 versus 9.5 kg, P < .0001). There were more abnormalities on the sonography of the hitting shoulder (1.7 versus 0.4, P < .0001) and in the same shoulders on MRI than on sonography (P = .0231). Compression of the suprascapular nerve was not observed. Pain in the hitting shoulder was present in 63% of the players, without clear correlations to the investigated clinical and imaging parameters. CONCLUSION: The prevalence of infraspinatus muscle atrophy in professional beach volleyball players is 30%. The typical, fully competitive player has subjectively unrecognized decreased strength of external rotation and frequent unspecific shoulder pain. Therefore, abnormal clinical and imaging findings in the beach volleyball player should be interpreted with care.

Quadriceps tendinosis and patellar tendinosis in professional beach volleyball players: sonographic findings in correlation with clinical symptoms.

The purpose was to assess quadriceps and patellar tendinosis in professional beach volleyball players and to correlate ultrasound findings with clinical symptoms. During a grand-slam beach volleyball tournaments all 202 athletes (100 men and 102 women) were invited to participate at this study. Sixty-one athletes (38 male, mean age 29.6, 23 female, mean age 27.1) were included. The dominant leg was right in 51 (84%) and left in ten athletes (16%). Lysholm knee score and pain during the game was assessed using a visual analogue scale. Sonography of the quadriceps tendon and the patellar tendon was performed by a blinded sonographer. Sonographic findings were compared between both legs and correlated to clinical findings using a regression analysis. Quadriceps tendinosis was diagnosed in 13 (21%, dominant leg)/21 (34%, non-dominant leg), patellar tendinosis in 13(21%)/18(30%). Only sonographic findings at the quadriceps tendon were significantly associated with pain: thickness of the quadriceps tendon (mean diameter 6.9 mm/7.1 mm, significant for both legs P = 0.011/P = 0.030), abnormal echo texture (11/16; P = 0.001/P = 0.228), areas with positive power Doppler signals (mean number 0.3/0.4; P = 0.049/0.346), calcifications (mean number: 0.9/1.1; P = 0.021/0.864). A relationship between findings at patellar tendon was not found. Quadriceps tendinosis is as common as patellar tendinosis in professional beach volleyball players. Thickening and structure alteration of the quadriceps tendon is associated with anterior knee pain during beach volleyball.