Replacing sedentariness with high-intensity physical activity enhances cardiorespiratory fitness in children

As little as 10 minutes of high-intensity physical activity per day reduces the amount of adipose tissue and enhances cardiorespiratory fitness in 6-8-year-old children, according to a new study from the University of Eastern Finland. The higher the intensity of physical activity, the stronger the association with the amount of adipose tissue. Exchanging sedentary behaviour -mainly sitting - for even low-intensity physical activity reduces the amount of adipose tissue. In order for physical activity to enhance cardiorespiratory fitness, the intensity needs to be at least moderate.

The results published in Sports Medicine are part of the Physical Activity and Nutrition in Children (PANIC) Study carried out in the University of Eastern Finland. The study was conducted in collaboration with the University of Cambridge.

The study investigated the associations of physical activity and sedentary time with body adiposity and cardiorespiratory fitness in 410 Finnish 6-8-year-old children. Physical activity and sedentary time were assessed using a combined heart rate and movement sensor, Actiheart. Body adiposity, on the other hand, was measured using dual-energy X-ray absorptiometry (DXA), and cardiorespiratory fitness was assessed using a maximal exercise test on a cycle ergometer. Various confounding factors including diet quality and sleep length were controlled for in the analyses.

The study showed that the more children spent time doing physical activities, the lower their total body and central body adiposity were. The association between physical activity and body adiposity grew in tandem with physical activity intensity. Children engaging in as little as 10 minutes of high-intensity physical activity every day had 26-30% less central body fat than children who did not engage in high-intensity physical activity. The intensity of physical activity had to be at least moderate in order for it to be associated with enhanced cardiovascular fitness.

The findings indicate that exchanging 10 minutes of sedentariness for 10 minutes of high-intensity physical activity decreases the total body and central body adiposity by 13 per cent. Moreover, replacing sedentariness with light or moderately intensive physical activity also seems to decrease the amount of adipose tissue, but not as much as high-intensity physical activity. Exchanging 10 minutes of sedentariness for moderate- or high-intensity physical activity enhances cardiovascular fitness.
The findings indicate that even small changes to exercise-related lifestyle habits can have an impact on children's weight management and cardiovascular fitness. Increasing the amount of physical activity at various intensity levels and reducing the amount of sedentary time seem to be an important way of preventing overweight and enhancing cardiovascular fitness in childhood.