Designing wearable technology solutions to measure technique and risk factors associated with elbow injury development in tennis players

Abstract

Medial and lateral elbow tendinopathy injuries are common in tennis players. Suggested risk factors include improper stroke technique, repetitive overload nature on the forearm musculature, grip strength and vibration frequencies. However, currently it is not known if the forehand tennis stroke itself contributes to the development of elbow tendinopathy, especially in the context of the level of playing experience, spin level applied to the ball and preferred forehand grip position.

We conducted a systematic review focused on the current applications of wearable technologies for player motion analysis in racket sports and the data analysis methods used to quantify and evaluate player motion under realistic playing conditions. Our findings showed inertial measurement units and electromyography sensors were the most common types of sensors used in the wearable devices.

We then designed, prototyped and tested a novel wearable device (TRAM-2) which can simultaneously measure player technique (changes in racket face angle and racket head speed) and risk factors associated with elbow tendinopathy development (grip strength, forearm muscle activity and vibrational transfer) on a large cohort of tennis players of various levels of playing experience under realistic playing conditions for the forehand stroke. TRAM-2 was first tested on 4 players (2 experienced and 2 recreational) in a pilot study and then on 50 tennis players (25 experienced and 25 recreational) under realistic playing conditions and the results were statistically analysed using statistical parametric mapping analysis. Our key findings are the first to show and contradict the concepts of (1) higher grip strength leads to increased transfer of shock and vibration to the player’s arm and (2) when skeletal muscles stiffen near maximum contraction, the vibrations from impact are transferred more efficiently up forearm when compared between the flat and topspin spin levels.