Allostatic Load Detected By Wearable Precedes Overuse Musculoskeletal Injury In Us Marine Corps Officer Candidates

Overuse musculoskeletal injuries (MSKIs) impede the physical readiness of military personnel. Allostatic load (AL) theory posits that stress-induced physiologic activity leads to musculoskeletal pathology toward overuse MSKIs. Analyzing the physiologic mediators of AL by wearables before overuse MSKI onset may verify their use for preventive means in this populace. PURPOSE Assess the physiologic activity of mediators of AL by a wearable in US Marine Corps Officer Candidates (MOCs) before overuse MSKI onset versus those who did not sustain overuse MSKI during a 10 wk Officer Candidates School (OCS) training course. METHODS Wearables recorded energy expenditure (EE; kcal/day; kcal/kg/day), sleep architecture (time [hh:mm:ss/night] and percent [%/night] of deep, light, REM sleep, awake bouts, total sleep), daytime heart rate (HR; bpm/day), sleep HR (bpm/night), distance (m/day) and steps (steps/day) during OCS. Data after first overuse MSKI was removed. Mann-Whitney U-test compared device metrics between groups (α = 0.05). RESULTS 69 MOCs (23 women) were included. 21 MOCs (8 women) sustained an overuse MSKI. In both sexes, MOCs before overuse MSKI showed significantly greater relative EE (+2.94-7.86 kcal/kg/day, p < 0.001) and lower % REM sleep (-7.89--5.22%/night, p = 0.001-0.009) compared to MOCs who did not sustain an overuse MSKI. Men before overuse MSKI showed significantly higher daytime HR (+4.93 bpm/day, p < 0.001), sleep HR (+3.89 bpm/night, p < 0.001), absolute EE (+692.00 kcal/day, p < 0.001), light sleep (+00:24:00/night, p < 0.001), % light sleep (+5.5%/night, p < 0.001) and awake bouts (+00:01:00/night, p = 0.024) than men who did not sustain an overuse MSKI. Women before overuse MSKI showed significantly greater deep sleep (+00:45:00/night, p < 0.001), % deep sleep (+10.27%/night, p < 0.001) and lesser % light sleep (-5.44%/night, p < 0.001) and REM sleep (-00:22:30/night, p = 0.007) than women who did not sustain an overuse MSKI. Steps (men: +566 steps/day, p = 0.563; women: +528 steps/day, p = 0.669), distance (men: +225.30 m/day, p = 0.612; women: +209.21 m/day, p = 0.817) and total sleep (men: +00:17:31/night, p = 0.053; women: +00:24:01/night, p = 0.079) were similar between groups. CONCLUSION Wearables detected AL in MOCs before overuse MSKI onset to advise their use for overuse MSKI risk evaluation. ONR N00014-21-1-2725