Sleep duration and physical performance during a 6-week military training course.

Abstract

Sleep is vital in influencing effective training adaptations in the military. This study aimed to assess the relationship between sleep and changes in physical performance over 6 weeks of military training. A total of 22 officer-trainees (age: 24±5years) from the New Zealand Defence Force were used for this prospective cohort study. Participants wore wrist-actigraphs to monitor sleep, completed subjective wellbeing questionnaires weekly, and were tested for: 2.4-km run time-trial, maximum press-up and curl-ups before and after 6 weeks of training. Average sleep duration was calculated over 36 nights (6:10±0:28hr:min), and sleep duration at the mid-point (6:15hr:min) was used to stratify the trainees into two quantile groups (UNDERS: 5:51±0:29hr:min, n=11) and (OVERS: 6:27±0:09hr:min, n=11). There were no significant group×time interactions for 2.4-km run, press-ups or curl-ups (p>.05); however, small effects were observed in favour of OVERS for 2.4-km run (59.8 versus 44.9s; d=0.26) and press-ups (4.7 versus 3.2 reps; d=0.45). Subjective wellbeing scores resulted in a significant group×time interaction (p<.05), with large effect sizes in favour of the OVERS group for Fatigue in Week 1 (d=0.90) and Week 3 (d=0.87), and Soreness in Week 3 (d=1.09) and Week 4 (d=0.95). Sleeping more than 6:15hr:min per night over 6 weeks was associated with small benefits to aspects of physical performance, and moderate to large benefits on subjective wellbeing measures when compared with sleeping < 6:15hr:min.