Alteration of circadian rhythmicity with aging might depend on physical aerobic capacity.Methods.
Three groups of participants were established based on their peak oxygen consumption (Group 1 < 20mL/min/kg; Group 2 > 20mL/min/kg and <30mL/min/kg; Group 3 > 30mL/min/kg). Each participant had an individual evaluation of their circadian rhythmicity characteristics through two well-known circadian rhythms: core temperature and rest/activity cycles. Nocturnal sleep was also recorded using actimetry and diurnal vigilance tested in a car driving simulator.Results.
The amplitude of the oral temperature fluctuations for Group 1 is significantly lower ( p < .05) than that of Group 3. Group 2 ( p < .01) and Group 3 ( p < .05) were significantly more active during the day than Group 1. The index of inactivity during the night for Groups 2 ( p < .05) and 3 ( p < .01) was higher than Group 1. Results of the car driving simulation showed that for Group 1, the number of lane crossings was significantly higher than Groups 2 ( p < .01) and 3 ( p < .01). In addition, diurnal vigilance was lower in Group 1.Conclusions.
The biological clock seems to be enhanced in older participants with a higher level of physical capacity.