Physical activity buffers fatigue only under low chronic stress

Area of Science:

• Psychology
• Exercise Science
• Stress Research

Background:

• Fatigue is a prevalent complaint in the general population.
• Physical activity (PA) is known to have positive health effects.
• The immediate impact of daily PA on momentary fatigue, particularly moderated by chronic stress, requires further investigation.

Purpose of the Study:

• To investigate the hypothesis that everyday physical activity (PA) improves fatigue.
• To examine the moderating role of self-perceived chronic stress on the relationship between PA and fatigue.
• To assess the short-term effects of PA on momentary fatigue in healthy students under different conditions.

Main Methods:

• Thirty-three healthy students underwent two five-day ambulatory assessment periods (control and examination preparation).
• Participants used electronic diaries to report fatigue and completed saliva samples for cortisol and α-amylase.
• A triaxial accelerometer continuously recorded PA, and self-perceived chronic stress was assessed.

Main Results:

• PA level in the preceding 15 minutes did not predict momentary fatigue.
• No significant effect of condition (control vs. examination) on fatigue was observed.
• A significant interaction revealed that the fatigue-reducing effect of PA was stronger in individuals with lower chronic stress.

Conclusions:

• Everyday PA demonstrates an immediate short-term buffering effect on general fatigue, but only when individuals experience lower levels of chronic stress.
• The short-term benefits of PA on fatigue appear to be limited or absent in the face of higher chronic stress.
• Findings underscore the importance of considering chronic stress when designing PA interventions for fatigued populations.