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

Round 1

Reviewer 1 Report

This is a clearly written manuscript with appropriate methods and well defined questions. The authors present results of a study focused on evaluating the correlation between vitamin D levels and rotator cuff muscle strength. The study included professional volleyball players who were categorized into three groups based on their vitamin D status. The athletes assessed for age, height, body weight, BMI, and isokinetic muscle strength including internal rotation and external rotation strength of the shoulder. The authors conclude that they did not find a significant correlation between vitamin D status and isokinetic shoulder muscle strength. Other than the suggestions below, the manuscript is clear and appropriate.  

Comments:

Some this information is included in the discussion section, but it would be nice if authors can construct their argument in the discussion section around these questions:

Were the eating and outdoor training behavior of athletes monitored? Can the authors explain what they think might be the reason for variation in vitamin D status among athletes who were examined? It is possible that because these athletes are undergoing physical training on a regular basis, they may not exhibit any immediate impact of vitamin D insufficiency, however, individuals who are not as physically active may exhibit muscle strength weakness. What are the author’s view on this and if the authors could include this in the discussion section of the manuscript?

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

With pleasure I read the interesting manuscript entitled “The relationship between Vitamin D status and Rotator Cuff Muscle Strength in Professional Volleyball Athletes”, dealing with the impact of Vitamin D status on rotator cuff muscle strength in professional volleyball athletes. The authors conclude saying that vitamin D insufficiency is common in elite volleyball players, which result important for the athlete community in terms of performance issue approaches,without actually reporting innovative insights, and that the vitamin D status is not associated with isokinetic muscle weakness, which result in contrast with some published data, as the same authors declare in the manuscript. However, the innovation of the study is represented by the fact that the authors focus on the shoulder rotator cuff strength and they justify their results speculating that elite athletes are highly trained and have minimal margins for improvement and enhancement of muscle strength, which is quite interesting and deserves some further insights. Overall, the manuscript is coherent and demonstrates a sufficient background and structure to support the conclusions of the study. There are some oversights throughout the text such as the vitamin D status assessment, which are differently described in abstract and in materials and methods section and should be revised and made equal (Insufficiency: 20-30 ng/ml).

Author Response

Please see the attachment.

Author Response File: Author Response.docx