Effects of XXXX and strenuous physical activity on the rest-activity circadian rhythm: a study on 500 km and 1,000 km dogsled racers.

@entity1 @entity1949 @entity1295 @entity4934 @entity25
OBJECTIVE: Rest-activity circadian rhythm is strongly linked to an organism's entrainment. Sleep loss and prolonged @entity1295 could affect the circadian system, inducing @entity4934 . The Finnmarksl  pet is Europe's longest dogsled race. In this competition, lasting up to 7 days, @entity1 (mushers) are physically active most of the time, having little and fragmented rest. Therefore, the race provides an opportunity to investigate the effects of prolonged @entity25 . METHODS: Ten mushers, participating in the 500 km and 1,000 km categories, underwent continuous actigraph monitoring (5 days) before and after the race. During the competition, heart rate (HR) was recorded by an HR monitor. RESULTS: There was a reduction in the average activity values during the 24-hr cycle after the race. Although there were signs of a forward phase shift, these were weak and unstable. Nonparametric circadian rhythm analysis (NPCRA) showed reductions in interdaily stability (IS) and relative amplitude (RA). 1,000 km mushers also showed @entity25 . CONCLUSION: A period of 3 days of @entity1949 (3-4 hr of total rest per day), in which subjects were engaged in a prolonged physical effort, was enough to significantly affect the rest-activity rhythm. A longer period (5 days) in such a condition induced even more accentuated alterations, with a disturbance in nocturnal sleep. Disrupted sleep is common among hospitalized @entity1 and those working long shifts. This study demonstrates changes in the structure of the rest-activity circadian rhythm that can result and may suggest opportunities for intervention.
