Light physical activity throughout the day and physical function in older adults: A cross-sectional study

Research has demonstrated that habitual light physical activity (LPA) in later life may contribute to preventing muscle loss and disability in older adults. Given that LPA dominated overall physical activity duration throughout the day, investigating the impact of the timing of LPA on physical function among older adults is essential for optimizing health interventions. This cross-sectional study explored the association between LPA timing and performances in four physical function tests among older adults. This study explored the associations between diurnal patterns of light physical activity and physical function performance. The study involved 200 older adults attending the geriatric outpatient clinic at National Taiwan University Hospital. Participants were on average 76.3 years old (SD = 6.6), with 55.5% being female. We collected LPA data using wrist-worn accelerometers for a continuous 7-day period. Principal component analysis (PCA) was employed to categorize daily periods of LPA. Multivariable-adjusted linear regression analyses were conducted to examine the associations between LPA timing and performance in the following physical function tests: grip strength, basic mobility (Timed Up and Go [TUG] test), walking speed, and lower limb muscle strength (five sit-to-stand test). Adjustments were made for gender, age, moderate-to-vigorous physical activity, and average daily triaxial accelerometer wear time. The findings indicated that higher LPA levels during the morning to noon period (08:00-13:00) were positively associated with improved performance across all four physical function tests. Furthermore, increased LPA in the late afternoon (12:00-17:00) and evening (18:00-24:00) was positively associated with better outcomes in the basic mobility (TUG test), walking speed (6-m walking test), and lower limb muscle strength (five sit-to-stand test), after controlling for relevant confounders. This study underscores the significance of the timing of light physical activity in enhancing various aspects of physical function in older adults independent of MVPA. Timing of LPA plays a crucial role in enhancing physical function in older adults, with morning activity being particularly beneficial. This supports tailored activity recommendations for geriatric care.