Association Between Age and Achilles Cross-Sectional Area in NCAA Division One Collegiate Female Gymnast

Monitoring changes in Achilles cross-sectional area (CSA) or thickness may provide clinicians with insights into exercise-induced adaptations and the mechanisms of Achilles tendon injury. It has been reported that an increase in thickness of 20% or more along the course of the Achilles tendon from the proximal calcaneus may be a clinical sign of structural pathology. Evaluating the relationship between an athlete’s age and Achilles tendon thickness may offer a valuable metric for understanding tendon health. PURPOSE: This study evaluates the association between age and Achilles tendon thickness, CSA, and thickness change in collegiate gymnasts. METHODS: Bilateral Achilles tendon thickness was measured at the intermalleolar line (IMT) in twenty-four NCAA DI female gymnasts (age: 20.0 ± 1.6 yrs, wt: 57.8 ± 5.7 kg, ht: 159.5 ± 6.2 cm, experience: 15.6 ± 1.7 yrs). CSA was also measured at this point. Thickness measurements were also recorded at the calcaneal insertion (CT) and at the thickest portion of the tendon (T). Percentage difference in thickness was calculated between CT and T. RESULTS: Thirteen tendons (27%) demonstrated greater than 20% percent difference between T and CT. ANOVA assessing the effect of birth year, weight and height on IMT, it was found that birth year (p = 0.009) and height (p = 0.012) were significant predictors of IMT. A post-hoc Tukey HSD test indicated a statistically significant difference in IMT between individuals born in 2003 and 2002 (p = 0.03). ANOVA also revealed a significant difference in Achilles CSA (p = 0.049) based on birth year. A post-hoc Tukey HSD test indicated a significant difference between individuals born in 2003 and 2002 (p = 0.027) for Achilles CSA. Those born in 2003 had significantly smaller Achilles IMT and CSA than those born in 2002. CONCLUSION: In these gymnasts, birth year was significantly impactful, but this may be due to small sample sizes in each group (24 gymnasts born 2001-2006) and the potential impact of random height and weight variations. Additionally, 27% of gymnast tendons demonstrated probable structural signs of pathology. Despite this, gymnasts continue to participate fully in training and events. Future research should investigate the interaction between age and injury on tendon thickness and injury with a wider sample of participants.