Abstract

Background: Our objective was to identify the effect of sleep deprivation on a stress test simulating a military march, via changes in heart rate variability (HRV) in special mountain troops. Eight subjects from special mountain troops carried out a simulated march test on a treadmill. The incremental march test had 7 stages of 3 minute duration at a constant velocity of 5 km/h and slopes of 1, 3, 5, 7, 8, 9 and 10 %. To assess the HRV, two heartbeat records were taken over 5 minutes in dorsal decubitus position before and after the march test; the first session took place without sleep deprivation, and the following day with sleep deprivation. Results: The main finding of this study is that the physiological stress imposed by the simulated treadmill march is the same with and without sleep deprivation. There were no significant differences between pre and post HRV data in any of the situations, but effect size was moderate or large (d=0.2 was considered as the Smallest Worthwhile Change). indicating a highly relevant response. However, after comparing with and without sleep deprivation tests no changes were found (non-significant and non-relevant). Conclusions: The stress test performed, did not present differences in physical and physiological responses while being deprived of sleep over 24 hours. A simple test is proposed to evaluate the effect of sleep deprivation as a stressor agent. A treadmill test at a constant speed with increasing slopes would be performed and repeated the following day after 24 hours of sleep deprivation.