Relationships Between Sedentary Behavior, Physical Activity and Cognitive Function of the Elderly Based on Isochronous Substitution Model

Objective Isochronous substitution model was adopted to simulate different physical activities and sedentary behavior (SB) to examine the changes of cognitive function of the elderly.

Methods 308 elderly people in Nanjing were selected by multi-stage and hierarchical sampling method. The time of SB, light physical activity (LPA) and moderate to vigorous physical activity (MVPA) were measured by three-dimensional accelerometer. The cognitive function was measured by Montreal Cognitive Scale (MoCA). The isochronous substitution model was used to evaluate the relationships between SB, LPA and MVPA and cognitive function.

Results ① After controlling age, educational background and wearing time, a positive correlation was found between physical activity and cognitive function. ② After 30-minute LPA isochronous substitution for SB, the computing ability of the elderly (β=0.080), directional ability (β=0.077) increased significantly (P<0.05). ③ After 30-minute MVPA isochronous substitution for SB, the performance function of the elderly (β=0.389), memory (β=0.611), attention (β=0.123), computing power (β=0.085), language ability (β=0.250), abstraction ability (β=0.168) and directional ability (β=0.080) were all significantly increased (P<0.01), otherwise it was decreased. ④ With the time increase of MVPA substitution for SB, the cognitive function increased rapidly; on the contrary, it decreased slowly. With the time increase of MVPA substitution for LPA, the cognitive function increased slowly; on the contrary, it decreased rapidly.

Conclusion ① 30-minute LPA or MVPA substitution for SB can improve the cognitive function of the elderly in varying degrees. ② 30-minute MVPA isochronous substitution for LPA can also improve the cognitive function of the elderly. ③ With LPA substitution for SB, the cognitive function increases slowly; on the contrary, it decreases slowly. With MVPA substitution for LPA, the cognitive function of the elderly increases slowly; on the contrary, it decreases rapidly. With MVPA substitution for SB, the cognitive function of the elderly increases rapidly; on the contrary, it decreases slowly.