What Happens to Your Body When You Stop Working Out?

Schedules change, injuries happen, and life causes unforeseen interruptions to your plans. If you’re a dedicated exerciser, being thrown off your usual program can feel daunting: Will you lose all your hard-earned gains in strength, speed, or endurance if you have to take a break?

Cardiovascular capacity will decline more quickly than strength or muscle mass, but some of the impact of detraining depends on the length of your break and what you do during your downtime. Your age and existing fitness level can be factors as well.

After a Few Days

For both cardiovascular and strength gains, taking a few days off for a long weekend, for recovery, due to minor injury or illness, or just because plans get in the way, won’t have a negative impact.

In fact, as physical therapist Grayson Wickham told Outside previously, a three or four-day rest period can actually be beneficial because it gives your body time to recover and get stronger following your last workout, especially if it was challenging.

After Two Weeks

As your time off increases, you’re more likely to see an initial decline in cardiovascular capacity than in muscular strength and mass. Much of that loss will be in your VO2 max, or the amount of oxygen your body can take in while exercising. As that number decreases, exercises such as running and cycling will feel more challenging and tiring, and your endurance may decline as well.

A small study published in 2022 found that a two-week pause in training resulted in a decrease in VO2 max among 15 male endurance athletes (though they maintained their muscular endurance).

A 2024 meta-analysis found that in trained endurance athletes, VO2 max is likely to decline by about seven percent after a 12-day break in training.

During a two-week break in training, you’re unlikely to see any decreases in muscle strength, though you may feel some initial stiffness or weakness when you first return to the gym.

After One Month

The 2024 meta-analysis mentioned above also found that after five weeks, VO2 max is likely to decrease by 10 percent. That decline continues as more time passes—13 percent at a month-and-a-half and 20 percent at around two months—up to twelve weeks, after which point no additional decreases were observed.

During this stretch, you’re still unlikely to notice any loss of muscle strength or size, though joint stiffness may continue to progress if you’re not moving much.

Over One Month and Beyond

A 2024 study found that if you’ve been training regularly, you’re more likely to regain your strength and size faster after a period of no exercise. In the study, male and female participants with limited strength training experience were put on a ten-week resistance training program, followed by ten weeks of no training, followed by a repeat of the initial ten-week program. Participants regained their muscle strength and size rapidly during the retraining cycle. The authors noted that, provided you have been training consistently, you don’t need to be “too concerned about occasional short-term training breaks.”

A 2022 meta-analysis came to a similar conclusion and noted that in trained individuals, strength and size gains were not fully lost after periods of no training and often were slightly above pre-training measurements.

What to Do During a Period of Time Off

It can be tempting to change how you eat and how much you eat during a break in working out since you’re not expending as many calories through exercise. But a calorie deficit can actually exacerbate muscle loss. Aim to maintain your existing protein levels, even when you’re not doing cardiovascular exercise or resistance training.

If possible, find other ways to move that don’t exacerbate an injury or illness to avoid muscle and joint stiffness and discomfort. Walking or doing low-impact activities like swimming or yoga can help you move your joints through their full range of motion without the intensity.

When you do get back to the gym, give yourself a little grace—workouts that once felt easy may feel a bit more challenging at first. Schedule time to warm up with dynamic mobility exercises that mimic the movements you’re about to do, and start at a slower pace or with lighter weights.