INFLUENCE OF PHYSICAL EXERCISE ON AGING RATS .1. LIFELONG EXERCISE PRESERVES PATTERNS OF SPONTANEOUS ACTIVITY

Physical exercise has been shown to delay a number of aging changes an d increase life expectancy but not maximum lifespan. We trained male S prague-Dawley rats in a treadmill from the age of 5 months to 23 month s. Up to this age the mortality (19%) was not different from that of t he sedentary controls (16%). The body weights of the trained animals r emained lower and reached a plateau, while those of the sedentary cont rols continued to increase. The spontaneous activity was assessed in a n open-field setting every-second month. Movement parameters (running distance, running speed, percentage of large and local movements), res ting time and number of changes of direction were calculated. The runn ing parameters were higher for the trained animals from the age of 12 months onwards, the relative difference increasing all the time. The r esting time was lower for the trained animals, while the number of cha nges of direction did not change. It is suggested that this retardatio n of decline of spontaneous physical activity is due to a slowing of d evelopment of sensorimotor disturbances. These observations are compat ible with a better preservation of cholinergic and dopaminergic activi ty.