Effect of exercise training on total daily physical activity in elderly humans

This study examined the effect of 12 weeks of exercise training on daily physical activity in elderly humans. Training consisted of a weekly group session and an individual session with cardio- and weight-stack machines. A group of 15 subjects served as the exercise group [EXER mean age 59 (SD 4) years]land 7 subjects as the controls [CONT mean age 57 (SD3)years]. Physical activity and physical fitness were measured before the start of training (T), at week 6 and week 12 (T-0, T-6, T-12 respectively) in EXER, and at T-0 and T-12 in CONT. Physical activity over 14 days was measured using a tri-axial accelerometer and physical fitness was measured during an incremental exercise lest. At T-12, mean maximal power output had significantly increased in EXER compared to [CONT 8 (SD 12) vs -5 (SD 9) W; P < 0.02] and mean submaximal heart rate (at 100 W) had reduced [-10 (SD 7) vs -2 (SD 6)beats min(-1); P < 0.05]. No differences or changes in physical activity were observed between EXER and CONT. At T-6, physical activity on training days was significantly higher than on non-training days (P < 0.001). When the accelerometer output of the training session was subtracted from the accelerometer output on training days, at T-12 non-training physical activity was significantly lower than on non-training days (P < 0.004). Accelerometer output of the individual training session at T-12 had significantly increased compared to T-6 (P < 0.05), whereas, accelerometer output of the group training session had remained unchanged. In conclusion, in elderly subjects an exercise training programme of moderate intensity resulted in an improved physical fitness but had no effect on total daily physical activity. Training activity was compensated for by a decrease in non-training physical activity.