Objective To evaluate whether deficits of elbow flexor and extensor muscle strength exist in lateral epicondylalgia (LE) in comparison with a healthy control population.

Design Cross-sectional study.

Participants 150 participants with unilateral LE were compared with 54 healthy control participants.

Main outcome measures Maximal isometric elbow flexion and extension strength were measured bilaterally using a purpose-built standing frame such that gripping was avoided.

Results The authors found significant side differences in elbow extensor (−6.54 N, 95% CI −11.43 to −1.65, p=0.008, standardised mean difference (SMD) −0.45) and flexor muscle strength (−11.26 N, 95% CI −19.59 to −2.94, p=0.009, SMD −0.46) between LE and control groups. Within the LE group, only elbow extensor muscle strength deficits between sides was significant (affected–unaffected: −2.94 N, 95% CI −5.44 to −0.44).

Conclusion Small significant deficits of elbow extensor and flexor muscle strength exist in the affected arm of unilateral LE in comparison with healthy controls. Notably, comparing elbow strength between the affected and unaffected sides in unilateral epicondylalgia is likely to underestimate these deficits.

Trial Registration Australian New Zealand Clinical Trials Register ACTRN12609000051246.