Identifying Differences in Elastographic Properties of Calf Muscles and Tendons Across Subsets of Tennis Players

Abstract

Objective. Calf strain occurs frequently in tennis players and has been termed "tennis leg". To date, there is a lack of information showing how injury history, age, gender, or level of play, may predispose tennis players to injury (1, 2). The purpose of this study was to investigate the elastographic properties of the gastrocnemius-soleus complex in a group of club-level tennis players. We hypothesized that elastographic properties of the gastrocnemius-complex are affected by age and sport specificity (tennis only vs multi-sport). Methods. Participants were recruited through contact personnel of a local tennis club. At the club's annual summer tournament, each participant voluntarily consented and completed a survey to obtain information about age, level of play, length of play, participation in other sports, relevant injuries, and relevant surgeries. Participants underwent ultrasonography that included visualization of the medial gastrocnemius musculotendinous junction, soleus muscle, and Achilles tendons, bilaterally. Shear wave speed (SWS) was gathered from ultrasonography for all tissues to provide a comparative standard unit of measurement. The data was analyzed with a mixed effects model. Results. 20 participants with mean age 33.5 years old (range, 14-61) were evaluated. There was a statistically significant trend in medial gastrocnemius SWS depending on age, participation in sports other than tennis, and two different metrics for skill level (highest level of competitive play and USTA NTRP rating). There was a statistically significant trend between Achilles tendon SWS and highest level of competitive play. Results showed no significant trends for any of the tissues and serving hand, whether the ultrasound was conducted before or after a match, or for any of the four metrics for tennis experience (times playing tennis per week, overall tennis experience, years playing > 3 times per week, and whether a player had > 10 or < 10 years of experience). No statistically significant trends were observed for the soleus muscle when compared to any of the demographics. Conclusions. Age, exclusively playing tennis as opposed to other sports, and two metrics of skill level (highest level of competitive play and USTA NTRP rating) significantly affected gastrocnemius SWS. Highest level of competitive play was the only metric found to affect Achilles tendon SWS. Soleus SWS exhibited no significant changes with any of the variables, despite following similar trends with gastrocnemius SWS.