woman runner breathing hard because she's out of shape


How fast do you fall out of shape?

How quickly do you lose your fitness?

The general rule is "use it or lose it," but how quickly you'll lose it depends on your:

  • fitness level
  • age
  • length of break
  • reason for the break

That's a lot of variables. So let me just say, every individual is unique and different. But, everyone who stops working out (deconditions) will experience changes to their muscles, cardiovascular system and weight in different ways.


The body likes to hold on to strength for as long as it can. Inactivity for most people (non-athletes) will result in decreased muscles strength at a rate of one to three percent per day with noticeable strength loss occurring after about two and a half to three weeks. But it depends on why you take the break.

If you're not sick and are able to work in some movement and light exercise, you can decrease this slide by up to four or five weeks without significant strength loss. If you are sick or completely immobilized (think bed rest), muscle strength can decrease by 50 percent in just three weeks. 

For athletes taking a break, general strength doesn't change much during a two week hiatus. But the muscles used for skills that are very specialized for certain sports, such as slow-twitch muscle fibers for endurance athletes, will decline at a faster rate. 

Cardiovascular system

Sadly, cardio lovers, we lose the conditioning strength of our heart and lungs more quickly than we lose muscle strength. When you work out regularly, every beat of your heart can handle more blood. When you decondition, your heart gradually loses its ability to handle extra blood flow -- up to five percent in 24 hours -- and your resting heart rate increases by four to 15 beats within three to four weeks before it plateaus. One study on the effects of deconditioning shows that VO2 max (the body's maximum oxygen intake) gains made in the last two months before a break are completely lost after one month of inactivity. 

For endurance athletes a study found that four weeks of inactivity resulted in a 20 percent decrease of their VO2 max. Athletes who had been training regularly for at least a year and then suddenly stopped lost half of the aerobic conditioning after three months.


When you take an extended break from your exercise routine, your metabolism will begin to slow and the number of calories you burn daily will change. That means you'll need to adjust your calorie intake to avoid weight gain.  

The way your body looks will begin to change also. Your muscles will eventually shrink back to where they started: Bye bye six pack. And any extra calories above what your body can burn will be stored as fat: Hello love handles. 

Stopping the slide

Now the good news: The effects of deconditioning on your muscles, cardiovascular system and weight can all be reversed, (wait for it) with exercise. And the bad news: you're not going to get back into shape in a few days. Strengthening the muscles, increasing your VO2 max and losing the weight can take twice as long to build back as it did to lose. 

Exercise puts stress on the body and any good workout program includes rest days to help your body recover. There is a benefit to active recovery (light activity) and complete rest. Here are some tips to stop the slide of deconditioning:

  • Avoid the all or nothing mindset. You don't need to do 30 minutes of exercise all at once. If a project kept you from your three mile run, try to squeeze in two 10 minute walks. Doing something, instead of nothing can help you feel better about yourself, both physically and mentally.
  • Don't let your busy schedule be an excuse. Look at your schedule ahead of time and pencil in small amounts of time to exercise. Try to weave in ways to be active throughout you day, like walking and climbing stairs.
  • Do body-weight workouts. You don't need a gym to exercise, instead use your own body weight as resistance for strength training. Push-ups, squats, lunges and crunches are all examples of body-weight workouts you can fit in just about anywhere.
  • Accept your current abilities. Starting off your exercise routine too fast could lead to injury and frustration, and cause you to abandon exercise for good. If you were doing bicep curls at 15 pounds prior to your break, start at 10 pounds now and slowing increase from there.

Remember, it is good to incorporate rest days in your workout routine and take a break when you need to. Try not to judge yourself too harshly. The gym will still be there waiting for you when you are ready to return.


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