What happens to your cells when you don't move enough?

Muscles are more than just engines of movement: with every contraction they release hundreds of signalling proteins to other organs, such as the liver, fatty tissue and the brain. People who move little suppress that continuous flow of signals. This is probably one of the most important mechanisms behind the link between a sedentary lifestyle and chronic disease, even though the total effect on all those signalling proteins has not yet been fully mapped.

A clearly measurable consequence of inactivity is that cells respond less well to insulin. Muscle, liver and fat cells then process sugar less efficiently, and visceral fat (the fat surrounding your organs) accumulates. These are early disruptions that precede several chronic diseases. The risk of type 2 diabetes demonstrably increases as a result. Regular exercise partially reverses this: on average, long-term blood sugar levels fall by 0.4 to 1.0 percentage points, a clinically relevant difference.

Your blood vessel walls suffer as well. Inactivity promotes low-grade inflammation and affects the cells lining the blood vessels in a way that contributes to the formation of plaques, the beginning of atherosclerosis. The exact contribution of inactivity independent of other risk factors is difficult to isolate, but the relationship is biologically plausible and is becoming increasingly well supported.

For women with a predisposition to polycystic ovary syndrome (a hormonal disorder), an inactive lifestyle can further amplify the cellular dysregulation, including insulin resistance and oxidative stress. The evidence for this is more limited than for diabetes or cardiovascular disease, but the direction is consistent.

The good news: even less than the officially recommended 150 minutes of moderate exercise per week already delivers health benefits at the cellular level. And regularly getting up and moving throughout the day, even if you already exercise, helps limit the damage caused by prolonged sitting.