Elbow flexor and extensor muscle weakness in lateral epicondylalgia
Coombes BK, Bisset L, Vicenzino B.Br J Sports Med. 2011 Jun 27. [Epub ahead of print]
As sports medicine professionals, one of the first items ingrained into us during our education is to compare an injured joint or muscle to its uninjured counterpart. Through this process we can hopefully identify what is normal for the individual and if strength and stability deficits are present post-injury. Is it possible though, that comparing bilaterally might not be as strong an indicator to normal function as we have been lead to believe, especially if the dominant extremity is injured? In this study, Coombes et al. investigated elbow flexor and extensor strength in individuals with unilateral lateral epicondylalgia (LE). One hundred sixty-five individuals with the following symptoms were recruited: unilateral pain over the lateral epicondyle for > 6 weeks, aggravation from palpation, gripping and resisted wrist and/or finger extension. All patients in both the affected and control groups (n=54) underwent bilateral dynamometric voluntary isometric testing for both elbow flexion and extension with the maximum value from 3 repetitions in each direction being utilized for analysis. Pain-free grip strength was also measured via a digital grip dynamometer with the patient lying supine and the elbow in a relaxed, extended, and pronated position. The subjects performed 3 grip repetitions per side and were instructed to grip smoothly until pain was elicited on the affected side. Upon comparison, elbow flexion and extension strength of the affected arm was significantly less when compared to the matched arm of controls. The strength of the unaffected arm was comparable to that of the arm-matched controls. Pain-free grip strength was significantly lower for the LE group when compared to controls as well.
While these findings aren’t surprising, it should be noted that the dominant extremity was affected in 73% of the subjects. When doing side to side comparison under these conditions, the authors state that the deficits in both elbow flexion and extension strength tend to be underestimated. By virtue of this, getting a true read on the extent of the injury might be difficult due to the pre-existing asymmetry of strength. What are your thoughts on this? Can the same be said for any injury to the dominant extremity? When evaluating your athletes do you take into consideration the fact that the healthy non-dominant side is being used as your frame of reference and more than likely weaker than the healthy dominant extremity? Is it possible that rehabbing an athlete back to a point where the dominant side strength is equal to the non-dominant side is setting them up for future injury?
Written by: Mark Rice
Reviewed by: Stephen Thomas