LONG-TERM FITNESS TRAINING IMPROVES THE CIRCADIAN REST-ACTIVITY RHYTHM IN HEALTHY ELDERLY MALES

In old age, the circadian timing system loses optimal functioning. Thi s process is even accelerated in Alzheimer's disease. Because pharmaco logical treatment of day-night rhythm disturbances usually is not very effective and may have considerable side effects, nonpharmacological treatments deserve attention. Bright light therapy has been shown to b e effective. It is known from animal studies that increased activity, or an associated process, also strongly affects the circadian timing s ystem, and the present study addresses the question of whether an incr eased level of physical activity may improve circadian rhythms in elde rly. In the study, 10 healthy elderly males were admitted to a fitness training program for 3 months. The circadian rest-activity rhythm was assessed by means of actigraphy before and after the training period and again 1 year after discontinuation. As a control for possible seas onal effects, repeated actigraphic recordings were performed during th e same times of the year as were the pre and post measurements in a co ntrol group of 8 healthy elderly males. Fitness training induced a sig nificant reduction in the fragmentation of the rest-activity rhythm. M oreover, the fragmentation of the rhythm was negatively correlated wit h the level of fitness achieved after the training. No seasonal effect was found. Previous findings in human and animal studies are reviewed , and several possible mechanisms involved in the effect of fitness tr aining on circadian rhythms are discussed. The results suggest that fi tness training may be helpful in elderly people suffering from sleep p roblems related to circadian rhythm disturbances.