Elbow tendinopathy injuries are very common in tennis players. One of the commonly accepted theories describing the development of elbow tendinopathy in tennis is based on stiffness of the forearm skeletal muscle units and their repetitive overuse in the forehand stroke. Our objective was to use a novel microcontroller based wearable device to compare the influence of different forehand spin levels (flat, topspin and lob) and ball exit speed on forearm muscle activity in the potential onset of elbow tendinopathy in experienced adult tennis players. Peak normalised extensor carpi radialis (ECR) and flexor carpi radialis (FCR) muscle activity corresponding to each forehand shot and ball exit speed were determined and analysed. For the ECR shots (flat = 121, topspin = 272 and lob = 273) by 8 players, Kruskal-Wallis test (p < 0.001) and Post-Hoc tests revealed a significant difference between the flat and topspin spin levels (p < 0.01) and flat and lob spin levels (p < 0.001). For the FCR shots (flat = 125, topspin = 301 and lob = 303) by 9 players, Kruskal-Wallis test showed no significant difference between the three spin levels. For the corresponding ball speed, the Kruskal-Wallis (p < 0.001) and subsequent Post-Hoc (p < 0.001) showed that flat hits had the significantly highest ball speed followed by topspin then lob accordingly for both muscles included shots. Our results suggest that coaches could consider recommending players to hit forehands with topspin in order to potentially reduce the risk of developing lateral elbow tendinopathy.

The use of wearable devices for player motion analysis is becoming a popular method to measure kinematic parameters associated with player techniques in racket sports. This systematic review focused on identifying the current applications of wearable technology for player motion analysis in racket sports (tennis, table tennis, badminton and squash) through two research questions: (1) What are the existing applications of wearable technology for player motion analysis in racket sports? (2) What data analysis methods are used to quantify and evaluate player motion? A comprehensive search of MEDLINE, EMBASE, SPORTDiscus, Scopus, Web of Science, and IEEE databases was undertaken following PRISMA reporting guidelines. Included studies must have only used external wearable technology mounted to either the player or the racket for the potential application of player motion analysis in a racket sport, tested the wearable technology under normal playing conditions and not only focused on detecting/classifying the player's stroke or activity movement. Of the 6616 articles found, a total of 15 studies met the inclusion and exclusion criteria. Tennis and table tennis were the most popular sports researched and inertial measurement units and electromyography sensors were the most common types of sensors used. This review found that wearable devices were mainly used to analyze (1) movement similarities and differences of players at different playing levels, (2) variability in racket, upper limb and joint movement patterns and (3) movement differences associated with different ball spin levels. These technologies can create a new level of accessible personalized training in these sports.

Upper limb tennis injuries are primarily chronic, resulting from repetitive overuse. We developed a wearable device which simultaneously measures risk factors (grip strength, forearm muscle activity, and vibrational data) associated with elbow tendinopathy development resulting from tennis players’ technique. We tested the device on experienced (n = 18) and recreational (n = 22) tennis players hitting forehand cross-court at both flat and topspin spin levels under realistic playing conditions. Using statistical parametric mapping analysis, our results showed that all players showed a similar level of grip strength at impact, regardless of spin level, and the grip strength at impact did not influence the percentage of impact shock transfer to the wrist and elbow. Experienced players hitting with topspin exhibited the highest ball spin rotation, low-to-high swing path brushing action, and shock transfer to the wrist and elbow compared to the results obtained while hitting the ball flat, or when compared to the results obtained from recreational players. Recreational players exhibited significantly higher extensor activity during most of the follow through phase compared to the experienced players for both spin levels, potentially putting them at greater risk for developing lateral elbow tendinopathy. We successfully demonstrated that wearable technologies can be used to measure risk factors associated with elbow injury development in tennis players under realistic playing conditions.

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