Hoping to improve their health, many people opt for vigorous styles of exercise. New research, however, suggests that minimal-intensity, longer-duration physical activity may be best for insulin action and plasma lipids.
The study, published in PLoS ONE (2013; 8 ; doi: 10.1371/journal.pone.0055542), included 18 apparently healthy subjects around 21 years of age. Each participant was randomly selected to follow one of three protocols.
“In the sitting regime subjects were instructed to sit 14 hours per day, to walk 1 hour per day, to stand 1 hour per day and to spend 8 hours per day sleeping or supine,” the authors explained. “In the exercise regime 1 hour of sitting was replaced by 1 hour of vigorous supervised bicycling per day, [and] the rest of the day was spent similarly as during the sitting regime. In the minimal intensity physical activity regime, subjects were instructed to replace 6 hours of sitting with 4 hours of walking at a leisure pace and 2 hours of standing.”
Throughout the intervention, each participant wore an activity monitor to determine time spent active, steps taken, activity intensity and energy expenditure. The goal of the physical activity regimes was to expend 450 calories. Subjects were instructed to make no changes to current dietary habits, but to refrain from alcohol consumption. Insulin sensitivity and plasma lipid measurements were taken on the morning after the 4 days of each intervention.
Insulin sensitivity and plasma lipids improved in the minimal-intensity exercise group. There appeared to be no differences between the inactive group and the vigorous-intensity group.
“One hour of physical exercise cannot compensate for the negative effects of inactivity on insulin sensitivity and plasma lipids if the rest of the day is spent sitting,” the authors added. “Reducing inactivity by low-intensity activities such as walking at a leisurely pace and standing is more effective than physical exercise in improving these parameters in sedentary subjects.”