Lean Mass Is Predictive Of Lower Extremity Tendinopathies In Female Army Basic Combat Trainees

A large (n = 80,000), long-term observational study identified age, BMI, and alcohol consumption as risk factors for lower extremity tendinopathy-related conditions (TRCs). Analyses of data from trainees in U.S. Army Basic Combat Training (BCT; n = 2,988) may provide unique insight into risk factors for TRCs as trainees are of similar age and do not consume alcohol. Secondly, a more comprehensive anthropometric measurement (DEXA) should improve the predictive ability to identify sex-specific TRC risk factors. PURPOSE: To determine sex-specific therapeutic targets for the development of TRCs in BCT trainees. METHODS: All-cause TRCs occurring at or below the knee were identified using International Classification of Diseases-10 codes. Injured trainees (plantar fasciitis, n = 14; patellar tendonitis, n = 11; Achilles tendonitis, n = 8; other lower leg tendonitis, n = 8) were matched (1:2, if available) to uninjured trainees (n = 76) based on age, sex, and race/ethnicity. Conditional regressions assessed the sex-stratified relationships between pre-BCT anthropometric, demographic, and self-report survey data (physical activity, sleep quality, grit & resilience scores, and ACFT scores) and all-cause TRCs during BCT. RESULTS: Injured trainees were young (21 ± 4 yrs), majority female (n = 26, vs. male, n = 15), and comprised of White (34%), African American (27%), Hispanic (22%), and Other Combined Races (17%). After matching for sex, age, and race/ethnicity, anthropometric parameters of weight (p = 0.08), BMI (p = 0.07), lean mass (p = 0.12), fat mass (p = 0.40), and %BF (p = 0.94) were not significantly predictive of TRCs. However, after stratifying for sex, odds ratios for females show that greater weight (OR = 0.91; 95%CI = 0.84, 0.99; p = 0.02) and greater lean mass (OR = 0.87; 95%CI = 0.78, 0.98; p = 0.02) were protective against TRCs. Therefore, for every 1 kg increase in lean mass there was 12.9% reduction in odds of females sustaining a TRC. Unexpectedly, all pre-BCT demographic, and self-report survey data were unrelated. CONCLUSION: The weight-related protections against TRCs in female trainees may be partially explained by the protective effects of having more lean mass; however, lean mass was not predictive within men. Growth of lean mass should be the pre-BCT training focus of female trainees to reduce the risk of a TRC. Supported by: Authors’ views not official U.S. Army or DoD policy. Funding: USAMRDC