Prevalence Of Hypohydration In Military Servicemembers Before A Multi-day Field Training Exercise

Abstract

It is well established that hypohydration negatively impacts physical and cognitive performance. Despite the importance of hydration, athletes frequently participate in training or competition hypohydrated. While data exists in athletes, there is a lack of data on Military servicemembers’ (SM) hydration status prior to field training exercises or combat. For our nation’s Warfighters, starting a mission hypohydrated can put their lives at risk. Performance decrements can have profound consequences on mission readiness and decrease survivability and lethality on the battlefield. While the recently revalidated Military fluid replacement guidelines (TB MED 507) have been shown to effectively replenish known fluid losses without causing overhydration, they do not address hydration status before training events. PURPOSE: To describe the hydration status of Military SMs prior to a physically rigorous, multi-day field training exercise. METHODS: Data was collected from three training iterations from 2017-2019. In total, first morning void urine samples were collected from 93 Military SMs (2017, n=23; 2018, n=33; 2019, n =37). Hydration status was determined by urine specific gravity (USG) with cutoffs according to the American College of Sports Medicine (ACSM) and the National Athletic Trainers’ Association (NATA) guidelines: euhydration <1.010, minimal hypohydration 1.010-1.020, hypohydration 1.021-1.030, severe hypohydration >1.030. For each cohort, only USG data was collected. RESULTS: The mean (SD) USG for the sample was 1.020 (0.009). Using the ACSM cutoffs (hypohydration >1.020), 50.5% of Military SMs were hypohydrated at the start of the field training exercise. Using the NATA cutoffs, 18.3% (n=17) were euhydrated; 31.2% (n=29) were mildly hypohydrated; 40.9% (n=38) were hypohydrated; 9.7% (n=9) were severely hypohydrated. CONCLUSIONS: Despite the Military’s emphasis on appropriate hydration strategies, just over half of the SM cohort were hypohydrated, while approximately 10% were severely hypohydrated. Future studies need to explore these findings. Although this evidence is preliminary, TB MED 507 may need to be updated to provide specific and clear guidance on strategies for hydration assessment and fluid replenishment prior to participation in operational training events or combat.