Next to the rarely true excuse, “Of course I´m not too heavy… I just have heavy bones,” the couch potato gene could be the perfect excuse for those who find exercise something of a chore. It may not be an attitude problem: ‘I’m not lazy, it’s my genes!’

In investigating couch potatoes scientists have discovered why some of us have fun working out for hours while others lack energy and can barely summon the get-up-and-go to reach for the TV remote.

They believe they have identified the genes that produce an enzyme in our muscles during work outs called AMP kinase (AMPK), which controls the way we metabolize food into energy. It´s pretty straight forward: AMPK is switched on when you exercise. Those who generate large quantities of AMPK tend to have more energy. However those with lesser amounts of AMPK have less energy – and are likely to be out of breath immediately.

Dr. Gregory Steinberg from the McMaster University in Ontario, Canada, believes the discovery could lead to treatments for those who find it difficult to exercise, including the high risk groups of obese patients, and those suffering from asthma.

His research team announced the news after finding significant results while working on two groups of mice: one healthy group and one bred without the two suspected genes behind AMPK production. (Scientists regularly remove or “knock out” genes to study a gene’s function).

Dr. Steinberg and his team watched both mice groups during their routine work out, including their favorite: running!

Interestingly the mice looked identical but while the normal mice could run for long distances, those without the genes for the AMPK enzyme in their muscles could only run a short distance, becoming tired nearly immediately. The researchers studied these knock out mice in detail and found that the mice without the muscle AMPK genes had lower levels of mitochondria (the “energy factories” in cells) and an impaired ability for their muscles to take up glucose while they exercised. So these mice had a double handicap: their cells weren’t getting fuel and weren’t making energy.

When you exercise you boost the number of mitochondria in your muscles. If you don’t exercise, the number of mitochondria decrease and your overall energy level will decrease. So by removing these two genes the scientists identified one of the key regulators of the mitochondria: the enzyme AMPK.


One should be very careful about directly applying results from studies based on mice to humans. While mice are a very good model system for studying genetic mechanisms and behavior, it just isn’t that simple. However the findings might still be important for individuals who find it difficult to exercise, such as the obese or asthmatics. Their inability to exercise may subsequently cause other complications such as diabetes and heart disease. And we know that exercise helps neurogenesis and slow down neurodegenerative diseases.


The scientific take home message for couch potatoes: since we are living a sedentary lifestyle and gradually removing activity from our lives due to emerging technology, the base level of fitness in the population is going down and that is reducing the mitochondria in people’s muscles. This in turn makes it so much harder for people to start exercising. It is way better not to let yourself get to that stage, but if you do no need to blame a genetic defect, there is something you can do about it!