Time-Course of Recovery for Biomarkers and Physical Performance after Strenuous Military Training: A Systematic Review

Abstract

The objective of the present review was to evaluate the time-course of recovery of biochemical marker levels and physical performance after strenuous military training, and identify which biomarkers are affected. A systematic literature search was conducted using the databases MedLine (Ovid) and Web of Science (WoS) to identify studies until January 2023. Varying relevant search terms were used, related to military training, Special Forces, physical performance, and biomarkers. Records were based on strict inclusion and exclusion criteria. Twelve studies met the inclusion criteria and were selected for this review. A variety of physiological and psychological markers were measured, and military training lasted from 4 to 62 days, with recovery periods varying from 24 h to 6 weeks. Among these studies, full recovery was observed in two studies, while seven studies showed almost full (79–90%) recovery, and in three studies, 44–63% of markers recovered after the measured recovery period. However, in some studies, additional markers could be defined as recovered, depending on the criterion for recovery. In the majority of the studies, most of the measured variables recovered during the follow-up, but often, some variables remained unrecovered, and at times, only modest recovery was seen. It is important to point out that recovery duration depends on the duration and intensity of the military training stressor. Overall, resolution varies between the markers, and sometimes, recovery might not occur, even after prolonged recovery. Therefore, it is important to measure the recovery status of soldiers with both biomarkers and physical performance markers, especially after strenuous training, to maximize operational capability during prolonged missions.