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Open AccessArticle

The Relationship between Vitamin D Status and Rotator Cuff Muscle Strength in Professional Volleyball Athletes

by Do Kyung Kim 1, Geon Park 1, Liang-Tseng Kuo 2,3,*,† and Won Hah Park 1,*,†
Department of Sports Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 03063, Korea
Department of Orthopaedic Surgery and Sports Medicine Center, Chang Gung Memorial Hospital, Chiayi 613, Taiwan
School of Medicine, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan
Authors to whom correspondence should be addressed.
The two authors contributed equally.
Nutrients 2019, 11(11), 2768;
Received: 23 September 2019 / Revised: 11 November 2019 / Accepted: 12 November 2019 / Published: 14 November 2019
(This article belongs to the Special Issue Vitamin D and Sport Performance)
This study aimed to examine the vitamin D status of professional volleyball athletes and to determine its correlation with shoulder muscle strength. We included 52 healthy male professional volleyball players (23.2 ± 4.5 years), who were categorized by vitamin D status (<20 ng/mL: deficiency, 20–30 ng/mL: insufficiency, and >30 ng/mL: sufficiency). We examined the strength of the internal rotator (IR) and external rotator (ER) muscles of the shoulder by using an isokinetic dynamometer. Fourteen players (26.9%) had vitamin D deficiency, 24 players (46.2%) were vitamin D-insufficient, and 14 players (26.9%) were vitamin D-sufficient. There was no significant correlation between vitamin D level and shoulder muscle strength at 60°/s (IR, r = 0.159, p = 0.26; ER, r = 0.245, p = 0.08) and at 180°/s (IR, r = −0.093, p = 0.51; ER, r = −0.037, p = 0.79). Moreover, the isokinetic shoulder strengths were not significantly different across the three groups in all settings. In conclusion, vitamin D insufficiency was common in elite volleyball players. Though not being associated with isokinetic muscle weakness, vitamin D levels should be regularly monitored, and vitamin D should be supplied to young elite athletes, considering its importance for musculoskeletal health. View Full-Text
Keywords: vitamin D; muscle strength; volleyball; athletes; shoulder vitamin D; muscle strength; volleyball; athletes; shoulder
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Kim, D.K.; Park, G.; Kuo, L.-T.; Park, W.H. The Relationship between Vitamin D Status and Rotator Cuff Muscle Strength in Professional Volleyball Athletes. Nutrients 2019, 11, 2768.

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