Research using data from 2131 participants in the 2008 U.K. Health Survey suggests that regular exercise can partly counteract the negative health effects of being sedentary. The analysis grouped people into the following categories:
- physically active and low sedentary 'busy bees' (18.6% of the sample)
- physically active and high sedentary 'sedentary exercisers' (36.7%)
- physically inactive and low sedentary 'light movers' (6.8%)
- physically inactive and high sedentary 'couch potatoes' (37.9%).
Overall, physical activity was significantly associated with lower BMI, lower waist circumference, lower HbA1c levels (HbA1c is a modified form of haemoglobin, commonly used to measure glucose concentration; higher levels indicate poorer control of blood glucose levels), and higher HDL-cholesterol (the 'good' cholesterol). Sedentary time was associated with lower HDL-cholesterol levels.
None of that is a surprise, of course. The interesting aspect of this study is its attempt to disentangle physical activity and sedentary time.
In comparison to the couch potatoes, both busy bees and sedentary exercisers had significantly lower BMI and HbA1c levels, and higher HDL-cholesterol levels.
Busy bees (but not sedentary exercisers) also had lower waist circumferences. Compared to couch potatoes, light movers had only one improvement: higher HDL-cholesterol levels.
What all this shows is not simply the importance of physical activity for health, but that physical activity offsets some of the evils of a high sedentary time. It also suggests that not being sedentary doesn't take you all that far — you still need to exercise.
Bakrania, K., Edwardson, C. L., Bodicoat, D. H., Esliger, D. W., Gill, J. M. R., Kazi, A., … Yates, T. (2016). Associations of mutually exclusive categories of physical activity and sedentary time with markers of cardiometabolic health in English adults: a cross-sectional analysis of the Health Survey for England. BMC Public Health, 16, 25. http://doi.org/10.1186/s12889-016-2694-9