Associations of daily activities measured by a pattern-recognition activity monitor with overall and abdominal obesity in older people: the IMPACT65+ study

Objectives: The aims of the present study were: (i) to analyze the associations of the time spent in daily activities (i.e., lie, recline, passive sit, active sit, stand, walk at slow pace, walk at average pace, walk at brisk pace, and other activities) with body mass index (BMI) and waist circumference (WC); and (ii) to examine how theoretically reallocating time between these daily activities is associated with BMI and WC. Methods: The sample included 437 older adults (288 women), aged 65 to 92 years, participating in the IMPACT65+ study. The time in daily activities was assessed by the Intelligent Device for Energy Expenditure and Activity (IDEEA). BMI and WC were measured following standardized procedures. Associations of daily activities with BMI and WC were examined using linear regression models adjusting for potential confounders. Isotemporal substitution models were performed to estimate the theoretical effect of replacing one activity with another activity while holding total time constant. Results: The time spent lying and reclining was associated with increased BMI and WC, while the time spent standing, walking at average pace, and walking at brisk pace was associated with decreased BMI and WC. Isotemporal substitution analyses revealed significant hypothetical reductions in BMI and WC when reallocating 15 min from lying or reclining to standing or walking at average pace. Moreover, replacing 15 min from any sedentary activity or light physical activity (except for walking at average pace) with an equal amount of time in walking at brisk pace was associated with lower BMI and WC. Conclusions: This is the first study examining the activity specific and isotemporal associations of daily behaviors (considering body postures and movements) with overall and abdominal obesity in older people. The results could be used in the development of specific recommendations encouraging an active lifestyle in older people.