What happens to your cells when you don't move enough?
Moving too little demonstrably disrupts how your cells handle sugar, signals and inflammatory processes. Even a small increase in daily movement helps limit that damage.
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.
Claims are based on reviews, guidelines and mechanistic studies (PMID 22473333, 27810402, 40549398, 27189025, 33883728, 36190593, 21694556). Causality is most strongly supported for diabetes and fitness; for atherosclerosis and PCOS the evidence is more associative and limited.
How much exercise do I need to live longer?
The biggest health gain comes from just a little exercise. Going from nothing to 150 minutes per week gives a 31% lower risk of premature death; after that the benefit increases somewhat more, but levels off.
Is sitting a lot harmful, even if I exercise enough?
If you meet the exercise guideline, that largely neutralises the risk of prolonged sitting. If you do not meet it, every additional hour of sitting counts. Prolonged TV viewing is a point of attention even for physically active people.
How quickly do I lose fitness if I stop exercising for a while?
Your aerobic endurance declines quickly: a measurable difference is already present after 10 days. If you maintain your intensity when training less, you can limit the loss considerably.
Can cold showers make your cells healthier?
Cold showers do not demonstrably make your cells healthier: they actually inhibit growth and recovery processes in muscle cells after training, without delivering the supposed anti-inflammatory benefits. If you do strength training, it is better to delay the cold shower until after the recovery window.
Is it better to occasionally go on a long walk, or are short bursts of movement spread throughout the day more beneficial?
For fitness and day-to-day blood sugar control it makes little difference whether you exercise in spread-out bouts or in one continuous session; for the post-meal blood sugar peak, spread-out movement appears slightly more effective. Choose the approach you can most easily sustain.
Does walking do enough to maintain your muscles?
Walking alone is not enough to maintain muscle as you age. Add strength training and ensure adequate protein intake for the best results.