How quickly do I lose fitness if I stop exercising for a while?
A period of training protects your fitness for a while after you stop, but the older you are, the faster that effect fades. Start moving again as soon as possible to hold on to what you have built up.
Older people who stop exercising lose their functional fitness, such as balance, walking ability and mobility, more slowly than people who have never exercised. Studies in people over 60 show that a previous period of training still has a noticeable protective effect after stopping. The greater the gains made during the training period, the more is retained. At the same time, the older you are, the faster that protective effect fades.
In obese children, the positive effects on blood fat levels, such as cholesterol and triglycerides, appear to hold up reasonably well after 12 to 48 weeks of inactivity. But the evidence for this is thin: it comes from just five studies that differed considerably from one another, so firm conclusions cannot be drawn.
What happens inside the energy factories of muscle cells after stopping exercise cannot be stated with confidence based on the available studies in older people. What is clear is that exercise improves those energy factories, whether through endurance training or strength training. How quickly that improvement is lost remains unknown for now.
The broad health benefits of regular physical activity in people over 70 have been convincingly shown across 87 studies: a lower risk of dying early, reduced blood pressure, better blood sugar control, greater muscle strength and a better quality of life. That makes the conclusion straightforward: if you are forced to stop for a while, you keep some of your built-up fitness for a period of time. But the longer the break and the older you are, the more of those built-up benefits you gradually lose.
This answer draws on four studies, including one large combined analysis of 87 studies in people over 70 on the broad benefits of physical activity, and one analysis in people over 60 looking specifically at what remains of functional fitness after stopping exercise. The latter provides the most direct answer to the question, but the researchers themselves rate the quality of the evidence as moderate. The data on blood fats in children and on muscle-cell energy factories in older people are based on very small numbers of studies (five and six respectively) and are of limited quality; the researchers themselves emphasise that uncertainty.
When does your muscle strength start to decline?
Muscle strength reaches its peak somewhere between your thirties and forties and gradually declines after that. Regularly training your muscles with weights or resistance is the most effective way to slow that decline.
How much rest do my muscles need between workouts as I get older?
Getting older does not call for more rest, but for more regular training: at least two resistance-training sessions per week, supplemented with adequate protein, is the best-supported approach for counteracting muscle loss.
How much muscle strength do you lose per year after the age of fifty?
After the age of fifty, you can quickly lose 3 to 4% of leg strength per year, far more than muscle mass alone would suggest. Strength training, combined with adequate protein intake, is the most effective way to counter this.
How do I know if I am losing too much muscle mass (sarcopenia)?
A calf circumference below 33 cm or a slow walking speed are good reasons to ask your GP about a grip strength test and muscle mass measurement. You can use these as a first check at home, but a definitive diagnosis requires measurement by a doctor.
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.
How much exercise do I need to live longer?
The biggest health leap comes from just a little exercise. Going from nothing to 150 minutes per week gives a 31% lower chance of dying early; beyond that the benefit grows somewhat further but then levels off.