Achilles Tendon Cross Sectional Area Changes Over a Division I NCAA Cross Country Season
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Tracking Achilles tendon cross sectional area (CSA) changes may help clinicians understand exercise adaptations and Achilles tendon injury mechanisms. To track adaptations in the Achilles tendon in response to a cross country season. DESIGN: Longitudinal study. Musculoskeletal (MSK) ultrasound images were obtained in a research laboratory. Cross country athletes ran with no restrictions outdoors and indoors. Participants were Division I NCAA cross country athletes (N = 24, age = 19.9 ± 2.1 years, mass = 61.32 ± 20.16 kg, height = 168.92 ± 17.16 cm, sex = 8 males and 16 females). Achilles tendon CSA was obtained through MSK ultrasound imaging at a pre-season baseline measurement, every 3 weeks throughout the season, and at post-season for a total of 4 measurements. Participants followed their normal running regimen outlined by their cross country coach. The dependent variable was Achilles tendon CSA measured by ultrasound imaging. We used a repeated measures ANCOVA to determine differences in CSA over the cross country season. CSA increased from baseline (0.439 ± .081 cm), to 0.466 ± 0.096 cm at 3-weeks, to 0.471 ± 0.092 cm 6-weeks, and decreased to 0.451 ± 0.104 cm at the post-season measurement. The 3-week and 6-week measures significantly increased from baseline (F3,72 = 8.575, p < .001). Achilles tendon CSA increased during the cross country season, but returned to baseline values at the end of a cross country season. Clinicians should be aware of the changing nature of the Achilles tendon CSA when treating cross country runners.