Overnight sleeping heart rate variability of Army recruits during a 12-week basic military training course

• Published in: European journal of applied physiology 2022-09, Vol.122 (9), p.2135-2144
• Main Authors: Macartney, Michael J., Larsen, Penelope, Gibson, Neil, Michael, Scott, Drain, Jace, Peoples, Gregory E., Groeller, Herbert
• Format: Article
• Language: English
• Subjects: Biomedical and Life Sciences; Biomedicine; Cardiorespiratory fitness; Heart rate; Human Physiology; Military training; Occupational Medicine/Industrial Medicine; Original; Original Article; Sports Medicine; Tumor necrosis factor-α
• ISSN: 1439-6319; 1439-6327
• DOI: 10.1007/s00421-022-04987-3

Purpose This study aimed to quantify sleeping heart rate (HR) and HR variability (HRV) alongside circulating tumor necrosis factor alpha (TNFα) concentrations during 12-week Basic Military Training (BMT). We hypothesised that, despite a high allostatic load, BMT would increase cardiorespiratory fitness and HRV, while lowering both sleeping HR and TNFα in young healthy recruits. Methods Sixty-three recruits (18–43 years) undertook ≥ 2 overnight cardiac frequency recordings in weeks 1, 8 and 12 of BMT with 4 h of beat-to-beat HR collected between 00:00 and 06:00 h on each night. Beat-to-beat data were used to derive HR and HRV metrics which were analysed as weekly averages (totalling 8 h). A fasted morning blood sample was collected in the equivalent weeks for the measurement of circulating TNFα concentrations and predicted VO 2 max was assessed in weeks 2 and 8. Results Predicted VO 2 max was significantly increased at week 8 (+ 3.3 ± 2.6 mL kg −1  min −1 ; p