Context : Running-related Achilles tendon injuries have been observed more frequently in males, which may reflect sex differences in tendon morphology or mechanics during running. Males exhibit a larger Achilles tendon cross-sectional area and some measures of Achilles tendon loading in running, but sex differences in measures of tendon loading have not been thoroughly characterized. This study examines sex differences in the Achilles tendon cross-sectional area and Achilles tendon loading variables associated with running kinetics and kinematics. Design : Cross-sectional. Methods: Recruited from a university population, 26 female and 23 male healthy recreational runners ran at 3.35 m/s on an instrumented treadmill and were assessed using 3-dimensional motion capture, musculoskeletal modeling, and diagnostic ultrasound. A multivariate analysis examined differences between sexes in Achilles tendon loading and additional running variables with alpha set to .05. Mean differences (MD) and confidence intervals (CIs) were reported. Results: Males displayed greater peak Achilles tendon force (MD = 0.94 body weight BW; 95% CI, −1.48 to −0.33), peak gastrocnemius force (MD = 0.52 BW; 95% CI, −0.75 to −0.29), and Achilles tendon cross-sectional area (MD = 0.1 cm 2 ; 95% CI, −0.15 to 0.04) compared with females ( P .05). Conclusions : Male runners produced greater peak Achilles tendon force when running at the same speed, but similar peak Achilles tendon stress was observed between male and female recreation runners. Male runners had a greater Achilles tendon cross-sectional area. These findings may have implications to running-related injury based on sex.
Olver et al. (Thu,) studied this question.