Fatigability is closely associated with discoordination between heart rate variability and physical acceleration during free-moving days in younger women

BackgroundFatigability is related to several diseases and the autonomic nervous system. We investigated whether fatigability is associated with the coordination between the physical acceleration (PA) and heart rate variability (HRV) in women.MethodOverall, 95 adult women were divided into younger group (n = 50; age: 22–59 years) and older group (n = 45; age: ≥ 60 years). HRV and PA data were simultaneously obtained every minute for 24 h. We defined %lag0 as the percent ratio of lag = 0 min between HRV and PA in 1 h. Cornell Medical Index was used to determine the degrees of physical and psychological symptoms.ResultsIn the younger group in the hour before sleep, the participants with high fatigability scores had significantly lower (p < 0.05) %lag0 than did those with low fatigability %lag0. Additionally, those with higher fatigability combined with exhaustion in the morning had significantly lower %lag0 than did those without exhaustion in the hour before sleep but not in the hour after waking up (p < 0.05).DiscussionThese results suggest that the coordination between HRV and PA in younger women was closely associated with their fatigability in the hour before sleep. Additionally, exhaustion in the morning may be related to the discoordination of HRV and PA the previous night.