The Army Combat Fitness Test (ACFT) is a performance assessment used by the U.S. Army to assess a cadet’s strength, endurance, and agility with a series of six events to ensure that cadets are combat ready. Heart rate variability (HRV) is an instrument that measures cardiac autonomic modulation. SI was measured and calculated by using the CardioMood (sister company Corsano) equation n(SI = [Amplitude of Mode%]/[2*Mode* (RRmax – RRmin)]

Military Medicine, usad009, https://doi.org/10.1093/milmed/usad009