Is complexity of daily activity associated with physical function and life space mobility among older adults?

PURPOSE: Information about mobility, and physical function may be encoded in the complexity of daily activity pattern. Therefore, daily activity pattern complexity metrics could provide novel insight regarding the relationship between daily activity behaviour and health. The purpose of the present study was to examine the association between the complexity of daily activity behaviour, and mobility and physical function among community-dwelling older adults aged 75, 80, and 85 years-of-age.

METHODS: A total of 309 participants wore accelerometers concurrently on the thigh and the trunk for at least 3 consecutive days. Five activity states (lying, sitting, standing, walking, or activity other than walking) were defined in three different temporal grains (5 s, 1 min, 5 min) and Lempel-Ziv complexity was evaluated. We assessed complexity of daily activity behaviour with life-space mobility and physical function with distance in preferred pace 6 min walk, and short physical performance battery.

RESULTS: Weak positive associations were observed between complexity of daily activity and mobility and physical function at the finest temporal grains in both sexes (Spearman rho 0.19 to 0.27; p < 0.05). No significant associations were observed in the coarsest temporal grain in either sex.

CONCLUSIONS: Lempel-Ziv estimates of daily activity complexity with a fine temporal grain seems to be associated with community-dwelling older adults' physical function. The coarsest 5 min temporal grain may have smoothed out physiologically meaningful short activity bouts. Since complexity encodes information related to timing, intensity, and patterning of behaviour, complexity of activity could be an informative indicator of future physical function and mobility.