Measurements of tennis players' specific forearm muscle force imbalance to assess the potential risk of lateral epicondylitis

Abstract : Several studies suggested that lateral epicondylitis could potentially develop among tennis players presenting a muscle force imbalance, defined as a functional ratio weakness between agonist and antagonist muscles and/or a predominance of synergic muscles during the movement. Consequently, the measurement of muscle force capability and the assessment of imbalance between antagonist and agonist muscle groups could be useful in the context of clinical follow-up, ascertaining the subject's functional capabilities to return to tennis practice. The purpose of the present study was to develop a method to quantify subject's specific imbalance in forearm muscles to improve the knowledge about lateral epicondylitis. The study included a group of healthy male tennis players (n=11, no history of musculoskeletal problems) and specific tennismen profiles (recovered lateral epicondylitis (n=2), expert (n=1) and woman (n=1)). Maximal isometric net torques in both flexion and extension were measured at the metacarpophalangeal and wrist joints using an isokinetic ergometer. Tennis players' specific fingers and wrist muscle force imbalance between agonistic and antagonistic prehension muscles were estimated using a twostep calculation procedure including (i) an EMG-calibration procedure in order to integrate the muscle coactivation in net joint torques calculation and; (ii) the calculation of the antagonist/agonist torque ratio from corrected joint torques. The results showed dissimilar muscle force imbalances between the healthy men group and recovered lateral epicondylitis players. The observed differences between healthy players and recovered lateral epicondylitis suggested that the proposed method of muscle force imbalance estimation may provide a useful assessment of functional recovery in lateral epicondylitis. (C) 2014 Elsevier Ltd. Open access under CC BY-NC-ND license.