Effect of time of day on the relationship between mood state, anaerobic power, and capacity

Mood state was estimated in six men using the Profile of Mood States questionnaire, with a "right now" directional set prior to performance of a modified Wingate power test, once at 03.00 hr., 09.00 hr., 15.00 hr., and 21.00 hr., on different days. Anaerobic power was measured as peak power output in 5 sec., and anaerobic capacity was measured as total external work performed during the 30-sec. test. Intraindividual difference scores were calculated as a subject's score minus his mean over the four tests. Multiple regression analyses showed that time of day and the Profile of Mood States fatigue score accounted for 51% of the variance in peak power and 62% of the variance in anaerobic capacity. However, the relationships between fatigue and subsequent anaerobic power and capacity reached statistical significance only at 21.00 hr. These results suggest that intraindividual differences in the mood state are related to subsequent performance. Greater than usual levels of fatigue are associated with reduced performance capacity. However, this relationship is dynamic and is dependent upon the time of day.