How Fast Do You Lose Fitness When Not Exercising?

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When it comes to fitness, we've all heard the saying, "Use It or Lose It." While it's true that when you stop exercising you lose fitness, how quickly you lose it depends on several factors, including how old you are, how fit you are, how long you have been exercising, and how long you stop.

Losing fitness when you stop working out, also called detraining or deconditioning, is one of the key principles of conditioning.

The principle of use/disuse simply means that when we stop exercising, we generally begin to decondition and lose both strength and aerobic fitness. Most of us need to stop exercising on occasion for any number of reasons. Illness, injury, holidays, work, travel, and social commitments often interfere with training routines. When this happens, we will often see a decline in our level of conditioning.

Detraining in Fit Athletes

Deconditioning in fit athletes generally does not appear to happen as quickly or drastically as in beginning exercisers. In fact, one recent study looked at well-conditioned adolescent athletes who had been training regularly for a year. After three weeks of detraining, researchers found that the athletes' muscle strength and sport performance was not affected.

Detraining in Beginning Athletes

The outcome tends to be much different for new exercisers. A 2001 study followed new exercisers as they began a training program and then stopped the exercise. Researchers had sedentary individuals start a bicycle fitness program for two months. During those eight weeks, the exercisers made dramatic cardiovascular improvements and boosted their aerobic capacity substantially. At eight weeks, they quit exercising for the next two months. They were tested again and were found to have lost all of their aerobic gains and returned to their original fitness levels.

Detraining and Exercise Frequency and Intensity

Other research is looking at the effects of decreasing training level, rather than completely stopping all exercise. The results are more encouraging for athletes who need to reduce training due to time constraints, illness, or injury. A 2005 study followed sedentary men through three months of strength training, three times a week. They then cut back to one session per week. They found that these men maintained nearly all the strength gains they developed in the first three months.

There are many individual differences in detraining rates so it's impossible to apply all of these study results to all athletes and those who are new to exercise. But it appears that if you maintain some higher intensity exercise on a weekly basis, you can maintain your fitness levels fairly well for the long-term.

Studies have shown that you can maintain some of your fitness level depending on your level of athleticism even if you need to change or cut back on your exercise for several months. In order to do so, you need to exercise at about 70% of your VO2 max at least once per week.

If you stop exercise completely for several months it's difficult to predict exactly how long it will take you to return to your former fitness level. After a three-month break, it's unlikely that any athlete would return to peak condition within a week. The time it takes to regain fitness appears to depend on your original level of fitness and how long you've stopped exercise.

Tips for Maintaining Fitness During Time Off

6 Sources
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By Elizabeth Quinn, MS
Elizabeth Quinn is an exercise physiologist, sports medicine writer, and fitness consultant for corporate wellness and rehabilitation clinics.