Exploring patterns of accelerometry-assessed physical activity in elderly people

Abstract

Background: Elderly people obtain significant health benefits from physical activity (PA), but the role of activity patterns has scarcely been researched. The present study aims to describe the patterns of PA among different intensities of activity in elderly people. We assess how patterns differ between more and less active groups ('rare', 'average', and 'frequent'), and explore whether and how various PA parameters are associated with functional exercise capacity (FEC).

Methods: PA was measured in 168 subjects (78 males; 65-89 years of age), using a triaxial GT3X accelerometer for ten consecutive days. Subjects were divided into three groups by activity and the groups were compared. A multiple linear regression model was used to predict FEC.

Results: Participants greater than or equal to 80 years are most prone to being sedentary for long periods, while women and the obese are the groups most likely to spend insufficient time in moderate to vigorous PA (MVPA). Rarely active elderly people had a decreased proportion of long bouts of MVPA and light PA and of short bouts in sedentary behavior than frequently active subjects did (p<0.001). As predictors of FEC, younger age, lower BMI, male sex, better lung function, absence of multimorbidity, longer times and longer bouts of MVPA emerged as significant parameters (r(2)=0.54). Patterns of MVPA explained most of the variance.

Conclusions: PA patterns provide information beyond reports of activity alone. MVPA in elderly people may be increased by increasing the proportion of long bouts, in order to increase FEC as well as average PA. However, health conditions may limit PA. In rarely active people (often with reduced FEC, worse lung function, and diagnosis of multimorbidity or disability), longer periods of time in light PA may be sufficient to increase the overall level of activity.

Figure 1

Structure of physical activity variables. PA = physical activity; G = GINI-Index; high G = mainly few long bouts are responsible for the activity pattern; low G = mainly short bouts of similar length contribute to the activity pattern.

Figure 2

Visualization of PA counts per minute (A) and PA bouts (B) over three hours. PA = physical activity; MVPA = moderate to vigorous physical activity. A) The two lines (at 100 and 1952 counts) reflect the cut-points for light activity and MVPA. Values ≤ 100 correspond to sedentary PA, values between 100–1951 to light PA and ≥ 1952 to MVPA [10]. B) 1-minute-bout.

Figure 3

Lorenz curves of sedentary (A), light (B), and moderate to vigorous (C) physical activity. The GINI-index (G) corresponds to the area between the curve and the line of perfect equality (G = 0), marked by a solid line. High G = mainly few long bouts are responsible for the activity pattern; low G = mainly short bouts of similar length contribute to the activity pattern.

Figure 4

Distribution of PA bouts of sedentary (A), light (B), and moderate to vigorous (C) physical activity.