Daily composition of time spent in physical activity, sedentary behaviour, and sleep can impact quality of life in older Canadians

Take home message

• The way older adults distribute their time across movement behaviours (e.g., physical activity, sedentary behaviour, sleep duration) over the course of a day has implications for quality of life.
• Moving time out of ‘unhealthy’ behaviours (e.g., sedentary behaviour) into ‘healthy’ ones (e.g., moderate and light physical activity and to some extent sleep) can be favourable for quality of life.
• Shifting the focus to ‘the whole day matters’, that is the composition or ‘mix’ of movement behaviours within a 24-hour period, can encourage behaviour change in older adults and is less onerous than prescribing structured physical activity.

Background

• Associations between daily time spent in physical activity, sedentary behaviour, and sleep and quality of life are typically studied without considering that data on these behaviours is compositional, and they are co-dependent variables, that is, the time spent across these behaviours always add up to 24 hours and change in time spent in one is offset by an equal change in time spent in another.
• Previous studies have mainly assessed associations between individual movement behaviours and quality of life using traditional statistical techniques which is problematic and may lead to misleading conclusions, because those techniques cannot account for the compositional properties of movement behaviour data.
• Compositional data analysis is a statistical technique suitable for co-dependent variables that are relative components of a finite sum, such as time spent in movement behaviours adding up to the 24-hour day or another fixed amount of time (e.g., waking hours).

How the study was done

• 7,918 older Canadian adults (men and women) ≥ 65 years of age (mean age = 72.5 years) from the Canadian Longitudinal Study on Aging were studied.
• The associations between time spent in daily movement behaviours and quality of life were analysed using compositional data analysis.
• Daily time spent in physical activity and sedentary behaviour were derived from self-reported Physical Activity Scale for the Elderly (i.e., the “PASE” questionnaire) responses. Nighttime sleep was self-reported separately.
• The responses from those measures were converted to minutes and summed to derive a ‘daily movement behaviour composition’.
• Quality of life was assessed through the Satisfaction with Life Scale.
• Different time reallocation scenarios were tested (e.g., moving 30 minutes from sedentary behaviour into physical activity) to determine the impact on quality of life.

What the researchers found

• Daily movement behaviour composition was significantly associated with quality of life.
• Relative time spent in physical activity was marginally associated with quality of life, and the greatest decrease in quality of life occurred when time spent in physical activity was decreased and replaced with sedentary behaviour.
• Relative time spent in sedentary behaviour was negatively associated with quality of life.
• Relative time spent in sleep was positively associated with quality of life.

Conclusion

• The study offers a unique analysis of how shifts in time spent in different behaviours over the course of a day affect quality of life for older adults.
• Health-promoting initiatives for older adults should aim to reflect an optimal distribution of time spent in these behaviours across an entire day.