American Council on Exercise by American Council on Exercise

If you’ve been sidelined by an injury, or you’re considering taking a break from exercise, you might wonder if you’ll lose your hard-earned strength and endurance. Some loss of fitness is inevitable, but there are ways to help minimize it.

Here’s what happens to your body when you take a break from exercise.

Matters of the Heart

The degree to which cardiovascular fitness declines during a period of de-training depends upon what kind of shape you were in to begin with. Individuals who are extremely fit, such as highly trained athletes, experience a rapid drop in fitness during the first three weeks of detraining, after which the rate of loss tapers off.

A significant level of fitness—higher than that of an untrained person—is retained for about 12 weeks. Individuals with low-to-moderate fitness levels show little change in cardiovascular fitness within the first few weeks, but their abilities rapidly decline in the weeks immediately following that period.

Performance Jitters

The ability to perform a given sport or activity, whether it involves swinging a bat in softball or running 10Ks, invariably declines when the sport is abandoned for any length of time. Marathoners experience a noticeable reduction in endurance performance during a maximal aerobic treadmill test after just 15 days of inactivity.

Similarly, swimmers experience a decrement in arm strength within as little as a month layoff from their normal training regimen.

Numerous variables come into play when analyzing the ability to perform a particular sport-specific skill, making it difficult to analyze the effects of detraining. Some are like riding a bike—you never forget how—while others, such as the ability to deliver an accurate serve in tennis, involve specific timing and well-trained muscles.

Speaking of Muscles...

With the exception of a genetically blessed few, most of us have to work at building strength through formal or informal strength-training workouts. Again, well-trained athletes have the edge, because the positive effects of training remain evident for weeks, sometimes even months, after training is stopped.

Lesser-trained individuals can expect to see their muscle strength and conditioning levels decline at a slightly faster rate, though not at the levels seen in sedentary individuals.

Stem the De-training Tide

Experts agree that the best way to avoid losing much of the health and fitness benefits you’ve worked so hard to achieve is to do something. If you can’t find the motivation to run for a few weeks or longer, try walking instead. Cross-training is popular because it is a viable means of maintaining, or even increasing, one’s fitness level.

Runners can give their knees a break by switching to cycling, swimmers can work their legs on a stair stepper, and aerobics enthusiasts can take their workouts outdoors by hiking through a local park or reserve.

If an injury is keeping you from your favorite activities, take your worries to the pool. Of course, it’s always advisable to check with your physician before resuming exercise after an injury. Regardless of which activity you choose, be sure to progress gradually.

If boredom is the problem, now is the time to try that sport you’ve been considering for so long. In-line skating, tai chi, boot-camp workouts—whatever strikes your fancy. The key is to keep your heart and muscles challenged to minimize the de-training effects that come when you are taking a break from your usual routine.

Additional Resources

Common Sports Injuries, Causes, Symptoms, Diagnosis, and Treatments:
Detraining, Deconditioning, and Losing Fitness:
Dealing with Sports Injuries:

Preview the PDF