Evaluation of HRV as a predictor of response to a modified physical training program in ROTC cadets
Continually enhancing military personnel training is essential in order to prepare soldiers to perform optimally. The soldier’s ability to perform may be closely associated with baseline autonomic nervous system activity, indicated by heart rate variability (HRV). Variability in heart rate may be related to results on the Army Physical Fitness Test (APFT). PURPOSE: The purpose of this study was to determine if ROTC cadets’ APFT scores would improve following a novel 8-week training program, if performance on the APFT was related to baseline HRV, and if training adaptations in APFT performance were related to changes in HRV. METHODS: Twenty ROTC cadets (age 20 ± 1 yr) were evaluated on APFT at baseline, 4 and 8-weeks. A subset of 13 cadets completed HRV recordings using a validated smartphone application immediately upon awakening. The initial 3-days of HRV recordings served as baseline HRV. A subset of 8 cadets recorded HRV after the 4th week APFT through the end of the 8th week. An average of 3 readings at the beginning and end determined ΔHRV, and week 4 and 8 scores were subtracted to get ΔAPFT. RESULTS: APFT scores significantly improved in all fitness measures over the 8-week training program. Baseline HRV was moderately correlated with performance in each event, except for push-ups. Change in HRV and change in APFT scores from week 4 to week 8 was not significantly correlated. CONCLUSION: A periodized, progressive overload program significantly improved APFT scores. A trend towards moderate to strong correlations were found between performance tests and HRV, though they were not all significant in this sample size.
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