Effects of Two Programs of Physical Activity on Psychological Functions in Aging People

Physical activity (PA) is now well known as a positive moderator of cognitive aging. Several studies showed that PA programs reduce depression and improve cognitive functions. However, several questions remain unclear: (1) what kind of PA induces the larger effects? (2) What is the optimal duration of PA programs to induce these positive effects? (3) Does this benefit affect all psychological functions in the same way or is it selective to specific cognitive processes? PURPOSE: To determine which psychological function is positively and selectively affected by a PA program designed to improve aerobic fitness. METHODS: Thirty-six sedentary older adults (10 males, 26 females, M = 66.4 years, SD = 4.8) were randomly assigned to a swimming or a stretching program that lasted 5 months, 2 times a week (60 min per session). Swimming sessions included aquatic activities at target intensity between 50 and 70% of heart rate reserve (HRR). Stretching sessions included stretching, balance and limb coordination exercises at target intensity between 30 and 50% of HRR. All the participants performed a battery of physical and psychological tests three times: at the beginning of the PA program, at mid time and at the end of the program. VO2max. was evaluated by the Rockport 1 mile test. The psychological tests evaluated mental health (geriatric depression scale, self-efficacy questionnaire), processing speed and executive functions (the Stroop test, the random number generation task, 3 switching tasks, the 2-back task, 2 running span tasks). RESULTS: The two programs improved VO2max in the same way (M = 13.3%). Both PA programs reduced depression, improved self-efficacy, speed of information processing and executive functions. This positive effect of exercise was not observed for all psychological functions at mid time of practice. In addition, the swimming program improved behavioral inhibition and working memory updating significantly more than the stretching program after five months. CONCLUSIONS: The duration of the PA program, the type of exercise included in the program and the type of psychological tests used are three important determinants of the positive effect of exercise on mental and cognitive health. The improvement in VO2max does not seem to be a critical determinant of cognitive improvement.