A new study on healthy and physically active adolescents shows that just two weeks of inactivity affects the body adversely and can even increase the risk of chronic diseases.

A team of British researchers has studied 28 healthy and physically active young people who, before the study, took on average of 10,000 steps a day.

They were then instructed to take only 1,500 steps per day for two weeks and it turned out that their bodies had already begun to change.

The researchers saw, among other things, a decrease in muscle mass, an increase in fat mass, a decrease in insulin sensitivity and changes in metabolism.

Study design

The 28 study subjects were physically active men and woman with a mean age of 25 years and a mean BMI of 25 kg/m2. They wore a SenseWear armband to measure the amount of physical activity.

Comprehensive health checks including fat and muscle mass, mitochondrial function and physical fitness were done at the start of the study and end. A dietary journal was also undertaken to ensure no changes to food intake during the study.

Then a 14-day step reduction protocol began, which reduced participants’ activity by more than 80%.

Results

Cardio-respiratory fitness levels declined sharply and the participants were unable to run for as long or at the same intensity as previously.

They showed a substantial loss of skeletal muscle mass. A reduction in both total lean mass (average 0.36kg) and leg lean mass (average 0.21kg). They gained about 0,5 kilos (1 pound) in total body weight.

They also saw increases in waist size, central fat percentage, and triglyceride levels, or the amount of fat in their blood. The mitochondrial function also declined but this effect was not statistically significant.

This may lead to an increased risk of chronic diseases such as type 2 diabetes and heart disease as well as premature death, according to the researchers. study author Daniel Cuthbertson, Ph.D., of the University of Liverpool especially points out the harmful effects of central fat, that is related to visceral fat.

Visceral fat is the kind found deep within your abdominal cavity around vital organs like your liver and pancreas. This kind of fat is more metabolically harmful and can lead put you at risk of heart disease and diabetes, according to study author Daniel Cuthbertson, Ph.D., of the University of Liverpool.

The study was presented at this year’s European Congress on Obesity (ECO) in Porto, Portugal (17-20 May).

Reference:

University of Liverpool: Just 2 weeks of inactivity could lead to changes that increase risk of developing disease