You’re bound to fall off the fitness wagon sometimes. Whether it’s due to injury, illness or a busy schedule, even the most devout athletes have periods where they can’t hit the gym. But how long does it take for your previous hard work to come undone? The detraining phase, as it’s known, can take a major hit on your cardiovascular levels first. When you stop doing cardio for 10-12 days, your stroke volume, work capacity and cardiac output decline. VO2 max, which is one big measurement for cardio fitness, can drop as much as 20 percent in two weeks.

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Those who are just starting to work out feel the impact of taking a break the most. As PictureFit explains, a study showed that VO2 max dropped to baseline levels after eight weeks of inactivity. For athletes, it drops about 25 percent after a three-week break, which is significant for those training for competitions or sports.

You'll notice a difference in muscle mass after a three-week hiatus from strength training. Athletes can get away with four weeks of a break, unless they need tons of speed power and coordination, both of which start to decline after two weeks. Muscle mass decreases after about two to three weeks.

However some think it’s not really all muscle that you’re losing; they believe it’s mostly a water and glycogen loss instead. Glycogen can drop by as much as 50 percent in two weeks. One study showed that after three weeks, 1.5 pounds of lean mass was lost due to water. PictureFit says that while it might seem like your muscles are getting smaller, the reality is they might just appear that way due to the loss in liquids. As with most things, age plays a role in determining how much muscle you’ll lose as older individuals lose mass more quickly.

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For more about what happens to your body during a fitness break, watch the whole video from FitShow:

See Also:

Cardio Vs. Weight Lifting: Which You Should Do First For Optimal Performance, And Why

The New Normal For Body Size: Why Fewer Americans Are Trying To Lose Weight