The worst nightmare of any lifter — an injury, illness, or ill-timed vacation that sidelines you from your training. If you’ve ever taken a couple of weeks or months off from your workout program, you might have wondered how long it will take for your muscles to wither away. The dreaded wasting of muscle tissue we all fear is known as muscular atrophy.
How long will it take for your muscles to atrophy? And what even causes your muscles to get smaller, anyway? This article will take you through what happens to your muscles when you stop working out and, more importantly, how to rebound stronger than ever.
- What is Muscle Atrophy?
- What Causes Muscle Atrophy?
- How to Prevent Muscle Atrophy
- How to Rebound From Muscle Atrophy
Editor’s note: The content on BarBend is meant to be informative in nature, but it should not be taken as medical advice. The opinions and articles on this site are not intended for use as diagnosis, prevention, and/or treatment of health problems. Speak with your physician if you have any concerns.
To understand what’s going on when your muscles atrophy, it’s helpful to know a little bit about hypertrophy — the growth of skeletal muscles. Skeletal muscles are special because they respond directly to mechanical loading (e.g., lifting weights). Your cells adjust to make muscle protein synthesis occur faster than protein degradation, creating a net positive effect on growth. In other words — hypertrophy.
To maintain skeletal muscle mass, your muscles require a balance of protein synthesis and degradation. Degradation in this context is often normal — you’re always shedding old skin cells as you grow new ones, which is a similar process. If you’re generally healthy, are eating enough (particularly protein), and stimulate your muscles as needed, you can maintain your muscle mass.
Atrophy occurs when that balance is upset. Your muscles atrophy when the rate of degradation exceeds the rate of synthesis. Your myofibers shrink, and — because the structure of skeletal muscle is composed of myofibers — your muscles get smaller.
Working out isn’t simply a mechanical process — it’s also chemical. When you lift weights, your cells send each other a lot of signals. Those signals can say the equivalent of, “Hey, we need to get bigger to support this kind of lifting,” resulting in the kind of protein synthesis necessary to trigger hypertrophy. (1)(2)(3)
If the body cannot send those signals, however, you might find your muscles beginning to waste away or even be consumed for energy themselves. Multiple factors are contributing to the onset of atrophy.
Your muscles won’t disappear after a week of not training — but that doesn’t mean you don’t have to work to maintain them. Studies have found that various muscles can atrophy by as much as eight percent after only five days of complete inactivity, and a little less than three weeks of bed rest can atrophy lower leg muscles by up to 10 percent. (4)(5)
Even dramatically reducing the number of steps you take each day can significantly decrease your muscle volume. According to some literature, over a two-week period, a significant drop in steps taken can shrink your leg muscles by nearly three percent. (6)
While disuse does contribute to muscle wasting, recent literature has pointed to other, possibly more significant factors. A review of athletes suffering from a significant injury (in this case, an ACL tear) found that traumatic joint injuries are strongly correlated with muscle wasting. (7)
There can be other factors at play in atrophy when a severe injury occurs. It can also be about an injury traumatizing the connection between your nervous system and your muscle tissue.
Muscle atrophy can occur as a result of diseases or genetic differences, too. Folks who live through serious health complications are prone to significant muscle wasting. (8)
The diseases themselves and subsequent disuse can create a feedback loop. Your muscles might struggle because protein synthesis is far from a priority in the face of fighting medical conditions. Then, fatigue and pain from illness may cause folks to stay sedentary for prolonged periods of time, which also signals to the body that muscle protein degradation can continue.
You can’t always prevent accidents or illness, but many factors are in your control. To maintain skeletal muscle mass, your muscles require a balance of protein synthesis and degradation. But when degradation tips the scale and you’re losing more than you’re growing, you might start to atrophy.
Being as consistent as you can in your training doesn’t mean never taking breaks, though. The more you know about muscle atrophy, the more willing you might be to let your body rest and recover.
Yoga isn’t lifting weights — but that doesn’t mean it can’t help you maintain muscle mass. A 2018 study published in the Journal of Aging and Physical Activity suggested that regular yoga practice helps your muscles.
Yoga stimulates protein synthesis, so you don’t need to rely only on barbells to build muscle. (9) Whether you’re recovering from an injury or surgery, experiencing illness, or just want to supplement your routine, getting your body moving with some yoga can help fight muscle atrophy.
If you’re an experienced lifter, you don’t need to train every day to prevent muscle atrophy. According to a 2013 review of 27 studies on muscle development and retention in athletes, lifting between two and four times a week can maintain your muscle mass. (10) The more you engage with progressive overload in your training, the more you’ll “remind” your body to maintain and grow more muscle mass.
Take Breaks More Often
You don’t have to worry about losing all your progress when you miss a week of training over the holidays. If all other factors are kept equal, you won’t lose your gains if you take breaks from lifting. In fact, studies suggest that it takes at least three weeks of not lifting for muscles to atrophy. (11)
The takeaway? Yes, disuse can and does cause atrophy — especially in extreme cases. But if you regularly lift and are taking a break from the gym, you might not need to panic as much as you think. In fact, taking breaks more often can help you avoid overtraining and injury — which will likely force you to take unstructured, unwilling time off that can result in your hard-earned muscle going to waste.
If you do wind up losing muscle mass after a long period of not training, rest assured — all hope isn’t lost. You can retrain your body and reawaken your gains. It just might take a little bit of patience.
Trust Your Muscle Memory
If you’ve been an athlete for some time now, you’ll likely be able to get your full strength back fairly quickly. When your muscles go through hypertrophy, the cells grow new nuclei. Even if you stop strength training, the nuclei don’t just disappear.
When you start lifting again after a period of detraining, all your body has to do is kickstart protein synthesis. The nuclei in your muscle cells are still present, and research suggests they can help guide muscle back into fighting shape. (12) Therefore, retraining may not be as difficult on your body as starting training for the first time — and you can renew your gains more easily.
Especially if you’re coming back after illness or injury, get back into the game slowly. Just because your muscles may respond well to training doesn’t mean your body won’t have to re-acclimate.
Everything from your nervous system and lungs to your muscles won’t be ready to handle three plates on the bar right away if you’ve been gone for a while. Make sure you’re spending even more time than usual in the warm-up phase of your training sessions. Get back to lifting gradually to avoid injuring yourself by moving too much too quickly.
Supplement Your Protein
After an injury — or while you’re working back into your training — extra protein can help. A 2020 study published in the journal Advances in Nutrition found that protein intake combined with rehab work can kickstart muscular recovery. (13) In other words, even though you want to get back into training slowly, don’t skimp on your protein intake.
Even if you take all the necessary steps to prevent muscular atrophy, sometimes you’ll lose valuable muscle anyway. Unavoidable injuries, illnesses, or family needs can prevent you from training — or even physically moving around — for weeks on end. Your muscles may, indeed, suffer some temporary losses in the process.
But it helps to know that muscles don’t disappear overnight, especially if you’re still moving around in general — so taking strategic breaks from training may actually help hypertrophy in the long run. Rebounding from a bout of muscle atrophy likely won’t take as long as you fear, either. Just make sure you lift with your head instead of your ego, eat your protein, and remember that training for gains is as much about balance as it is about hard work.
- Dumitru, A., Radu, B. M., Radu, M., & Cretoiu, S. M. (2018). Muscle Changes During Atrophy. Advances in experimental medicine and biology, 1088, 73–92.
- Maestroni, L., Read, P., Bishop, C., Papadopoulos, K., Suchomel, T. J., Comfort, P., & Turner, A. (2020). The Benefits of Strength Training on Musculoskeletal System Health: Practical Applications for Interdisciplinary Care. Sports medicine (Auckland, N.Z.), 50(8), 1431–1450.
- Bamman, M. M., Roberts, B. M., & Adams, G. R. (2018). Molecular Regulation of Exercise-Induced Muscle Fiber Hypertrophy. Cold Spring Harbor perspectives in medicine, 8(6), a029751.
- V. R. Edgerton, M. Y. Zhou, Y. Ohira, H. Klitgaard, B. Jiang, G. Bell, B. Harris, B. Saltin, P. D. Gollnick, R. R. Roy, al. et. Human fiber size and enzymatic properties after 5 and 11 days of spaceflight. Journal of Applied Physiology. 1995;78(5). Published 1995 May 01.
- H., Akima, S. Kuno, Y. Suzuki, A. Gunji, T. Fukunaga. Effects of 20 days of bed rest on physiological cross-sectional area of human thigh and leg muscles evaluated by magnetic resonance imaging. Journal of Gravitational Physiology. 1997 Jan;4(1):S15-21. Published 1997 Jan. PMID: 11541171.
- Rikke Krogh-Madsen, John P. Thyfault, Christa Broholm, Ole Hartvig Mortensen, Rasmus H. Olsen, Remi Mounier, Peter Plomgaard, Gerrit van Hall, Frank W. Booth, Bente K. Pedersen. A 2-wk reduction of ambulatory activity attenuates peripheral insulin sensitivity. Journal of Applied Physiology. Published 2009 Dec.
- Lepley LK, Davi SM, Burland JP, Lepley AS. Muscle Atrophy After ACL Injury: Implications for Clinical Practice. Sports Health. Published 2020 Nov/Dec;12(6):579-586. doi: 10.1177/1941738120944256.
- Philip J. Atherton, Paul L. Greenhaff, Charles H. Lang. Control of skeletal muscle atrophy in response to disuse: clinical/preclinical contentions and fallacies of evidence. American Journal of Physiology. 2016 Sep 1; 311(3): E594–E604.Published 2016 Sept.
- Colletto M, Rodriguez N. Routine Yoga Practice Impacts Whole Body Protein Utilization in Healthy Women. Journal of Aging and Physical Activity. 2018 Jan 1;26(1):68-74. Published 2016 Jan.
- McMaster DT, Gill N, Cronin J, McGuigan M. The development, retention and decay rates of strength and power in elite rugby union, rugby league and American football: a systematic review. Sports Medicine. 2013 May;43(5):367-84. Published 2013 May.
- Ogasawara, R., Yasuda, T., Ishii, N. et al. Comparison of muscle hypertrophy following 6-month of continuous and periodic strength training. European Journal of Applied Physiology 113, 975–985 (2013). Published 2013.
- J. C. Bruusgaard, I. B. Johansen, K. Gundersen. Myonuclei acquired by overload exercise precede hypertrophy and are not lost on detraining. PNAS 107(34): 15111–15116. Published 2010 Aug.
- Howard, E. E., Pasiakos, S. M., Fussell, M. A., & Rodriguez, N. R. (2020). Skeletal Muscle Disuse Atrophy and the Rehabilitative Role of Protein in Recovery from Musculoskeletal Injury. Advances in nutrition (Bethesda, Md.), 11(4), 989–1001.
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