Heart Rate Variability And It's Association With Overuse Injury In College-aged Runners

Purpose: Mechanical loading and unloading of somatic tissue holds an integral role in overuse injury development. The autonomic nervous system (ANS) is a primary regulator of inflammatory mechanisms involved in tissue homeostasis and repair. Monitoring ANS may indicate somatic tissue response to physiological overloading associated with injury. This study investigated the association between ANS activity, indexed by relative changes in heart rate variability (ΔHRV), and the development of overuse injuries. METHODS: Division I cross-country athletes were recruited for a prospective, 3-month cohort study. Daily resting HRV was measured with Polar Team2 chest strap monitors; training load was recorded via session rate of perceived exertion. Overuse problems were measured by the Oslo Sports Trauma Research Centre (OSTRC) Overuse Injury questionnaire. A linear mixed effects model was used. RESULTS: N = 29, mean age 21(1), male = 18. Mean number of weekly HRV recordings was 5.6 ± 0.7. The average weekly response rate was 97%, with 25 of 29 (86%) participants responding to all questionnaires. Of 242 overuse problems, 42 (17%) were ‘substantial overuse problems’, resulting in moderate to severe reductions in training load and sport performance. No statistically significant associations were found between ΔHRV (relative changes in the root mean squared of successive RR intervals (ΔRMSSD), p = .801, 95%CI -1.70, .13; relative changes in the standard deviation of RR intervals (ΔSDNN), p = 0.096, 95%CI -.24, -.02) and overuse injury. No significant effects (p = 0.39) were found when study week was added to test for confounder effects. Training load was not significantly associated with overuse problems when added to the model with ΔRMSSD (p = 0.64, 95%CI -.06, .17) or ΔSDNN (p = 0.60, 95%CI -.06, .11). CONCLUSION: While not statistically significant, this study explored a novel idea of ANS monitoring for early detection of developing overuse injury. These findings represent a step towards improved understanding of overuse injury pathophysiology through monitoring patterns of change in a global, dynamic system involved in tissue injury and repair. Future research should incorporate broader, integrative approaches to investigate how complex interactions among risk factors contributes to the emergence of overuse injury.