A week or two off usually costs you little or nothing. After a few months off, you lose muscle size before you lose strength, and both tend to come back faster than they took to build the first time.
A week or two off
A short break is unlikely to set you back. A 2024 trial put young adults with some lifting experience on a 9-week program, and half of them stopped lifting for one week halfway through. Leg muscle grew about the same in both groups, though the group that rested gained a little less lower-body strength.
A 2020 study gave teenage athletes 3 weeks off. Their muscle thickness, strength and sport performance didn't drop. The group was small and all teenagers, so the results may not apply to adults. Taken together, the two studies suggest a holiday or a busy week or two won't cost you much of what you've built. Some lifters plan an easier week on purpose. See What is a deload week?
A month or more off
Longer breaks cost you some muscle and strength. Recent studies measured these changes after different amounts of time off.
| Time off | Who | What happened |
|---|---|---|
| 7 weeks | Men new to lifting | Leg lean mass rose 6.5% with training, then fell 4.6% during the break |
| 10 weeks | Adults new to lifting | Strength and muscle size both dropped |
| 12 to 24 weeks | Older adults | No clear drop in muscle size |
| 20 weeks | Adults new to lifting | Muscle size fell back to where it started, but strength stayed higher |
| 31 to 52 weeks | Older adults | A clear drop in muscle size |
Most of these studies were small, and most used people who had only lifted for a few months before their break. There's less recent research on people who have trained for years.
Strength lasts longer than size
In the 2019 study with a 20-week break, people's muscle size fell back to where it started, but they stayed stronger than when they began. The researchers credited a long-lasting learning effect, meaning your nervous system holds on to much of the skill of a lift even after the muscle shrinks.
Muscle memory and coming back faster
In a 2024 trial, adults trained for 10 weeks, took 10 weeks off, then trained for 10 more. During the first 5 weeks back, their strength and muscle size went up faster than in people lifting for the first time. By the end, they had caught up with a group that never took a break. The researchers suggested that occasional breaks probably matter little over years of lifting.
A 2018 study in a small group of men found something similar. They were new to lifting and gained 6.5% in leg lean mass, lost most of it during a 7-week break, then reached 12.4% above where they started after 7 more weeks of training. Training also changed how some muscle genes were switched on or off, and some of those changes lasted through the break.
The 2019 study didn't find this effect. A leg trained before the break didn't regain size any faster than a leg that hadn't been trained. A 2025 review concluded that muscle memory is real, though scientists are still working out why it happens.
How to keep your muscle when you're busy
You can hold on to what you've built with a lot less training. A 2021 review found that younger adults kept their strength and muscle size for up to 32 weeks with 1 strength session a week and 1 set per exercise, as long as the weights stayed heavy. Older adults may need up to 2 sessions a week and 2 to 3 sets per exercise to keep their muscle size.
So if you're down to one short workout a week during a busy month, keeping the weight heavy with fewer sets may keep most of your progress. See How many days a week to work out?
Cardio fitness during a break
Your cardio fitness can start to slip within the first few weeks. Researchers often measure it as VO2 max, the most oxygen your body can use during hard exercise. A 2022 review of 21 studies in athletes found that VO2 max dropped during breaks of under 4 weeks and dropped more during longer ones. Athletes who stopped for 1 to 3 months lost about as much as those who stopped for longer, so the drop seemed to level off after the first month or so.
Athletes who kept doing some exercise during their break lost less than those who stopped all training. All 21 studies were in athletes, so the results may differ if you exercise for general health.
In the 2021 review, people kept their endurance for up to 15 weeks with as few as 2 sessions a week, or with workouts cut to 13 to 26 minutes, as long as each workout stayed as hard as before. Those studies were in the general public, and the reviewers said there isn't enough data yet for athletes. Across cardio and lifting, the reviewers concluded that keeping the effort up seems to matter most. For one way to fit both into a week, see our cardio and lifting week example.
Coming back after a break
Your strength comes back quickly, but your first few sessions after a long break will likely leave you sorer than usual. See Is it OK to work out when you're sore? for why that happens and ways to ease back in. From there, most people add weight or reps a little at a time, the same way they built up the first time. See Progressive overload explained.
Common questions
Will I lose muscle if I take 2 weeks off?
Probably little or none. In the studies above, a 1-week break didn't slow muscle growth and a 3-week break didn't lower muscle thickness or strength.
How long does it take to get my muscle back?
Usually less time than it took to build. In the 2024 trial, people who took 10 weeks off caught up with a group that never stopped within 10 weeks of training again.
Does eating more protein stop muscle loss during a break?
Not on its own. A 2024 review of studies on people on bed rest or with a limb in a cast found that extra protein didn't prevent muscle loss. In the 2021 review, what kept muscle was lifting, even 1 heavy session a week.
Do older adults lose muscle faster?
Recent studies haven't compared younger and older adults directly. In the 2022 review of older adults, muscle size held for 12 to 24 weeks off and dropped clearly after 31 to 52 weeks.
Do fitter people lose more cardio fitness during a break?
For athletes, yes. In the 2022 review, athletes with a higher VO2 max lost more during breaks longer than 4 weeks, and athletes under 20 lost more than adults. Over breaks shorter than 4 weeks, the review found no clear difference by fitness level or age.
Sources
- Coleman M. et al. Gaining more from doing less? The effects of a one-week deload period during supervised resistance training on muscular adaptations. PeerJ (2024). (Disclosure: one author is on a fitness equipment company's advisory board, and another co-founded a training company.)
- Gavanda S. et al. Three weeks of detraining does not decrease muscle thickness, strength or sport performance in adolescent athletes. International Journal of Exercise Science (2020).
- Seaborne R.A. et al. Human skeletal muscle possesses an epigenetic memory of hypertrophy. Scientific Reports (2018).
- Halonen E.J. et al. Does taking a break matter: adaptations in muscle strength and size between continuous and periodic resistance training. Scandinavian Journal of Medicine and Science in Sports (2024).
- Psilander N. et al. Effects of training, detraining, and retraining on strength, hypertrophy, and myonuclear number in human skeletal muscle. Journal of Applied Physiology (2019).
- Grgic J. Use it or lose it? A meta-analysis on the effects of resistance training cessation (detraining) on muscle size in older adults. International Journal of Environmental Research and Public Health (2022).
- Serrano N. et al. Muscle memory theory: a critical evaluation. The Journal of Physiology (2025).
- Spiering B.A. et al. Maintaining physical performance: the minimal dose of exercise needed to preserve endurance and strength over time. Journal of Strength and Conditioning Research (2021).
- Zheng J. et al. Effects of short- and long-term detraining on maximal oxygen uptake in athletes: a systematic review and meta-analysis. BioMed Research International (2022).
- Hughes A.K. et al. The effect of protein or amino acid provision on immobilization-induced muscle atrophy in healthy adults: a systematic review and meta-analysis. Experimental Physiology (2024).
