Muscle Atrophy After Injury: How to Protect Your Muscle Strength While You Recover

A sprained ankle, a torn rotator cuff or a knee surgery can sideline you for weeks, and the injury itself is only part of the story. When a limb stays in a brace, a sling or a cast, the muscles around it get far less work, and they start to shrink.

That is muscle atrophy after injury, and it is one reason a leg or shoulder can feel weak long after the pain fades. The good news is that muscle lost to inactivity can be rebuilt. Here is why it happens, how quickly strength fades and what helps protect it while you heal.

Muscle atrophy is the wasting or loss of muscle tissue. After an injury, the most common type is disuse atrophy, which happens when muscles are not used enough. In healthy young adults, muscle lost to inactivity can be rebuilt by loading it again through exercise, according to a 2020 review in Sports Health on muscle atrophy after ACL injury. The same review notes that after a traumatic joint injury such as an ACL tear, atrophy can continue even with exercise, so the goal during recovery is to limit how much strength you lose and follow a guided rehab plan.

Injuries reduce muscle use in several ways, and many of them are part of protecting the injured tissue. It is also why an arm or leg often looks thinner after cast removal. This is different from the gradual changes in muscle power that come with age, which our guide for aging athletes covers.

Muscle loss from disuse starts quickly. A 2022 review by Hardy and colleagues in the Journal of Cachexia, Sarcopenia and Muscle, the time course of disuse muscle atrophy of the lower limb, found that healthy adults lost measurable quadriceps size within the first days, averaging about half a percent per day over the first two weeks.

The review measured muscle size, not strength, but in their discussion the authors cite earlier research showing that the early loss of muscle function can be even greater than the loss of size. Either way, the first two weeks of an injury matter.

You cannot always avoid some muscle loss after an injury, but you can limit it. Loading the muscle through exercise is what rebuilds it, with nutrition as a supporting countermeasure. During recovery, that comes down to a few practical habits.

Food is one of the few things you fully control while you heal. A 2020 review in Nutrients by Marshall and colleagues on nutritional strategies to offset disuse-induced muscle atrophy in older adults concluded that, for this group, a nutrient-rich, whole-food diet with adequate high-quality protein is the leading nutritional strategy for protecting muscle during periods of disuse. The authors also see a possible role for targeted supplements, while noting that most of the evidence comes from healthy volunteers and calling for more research.

As a clinical member of Avastar® Health Systems, our sister brand for supplements, we can point patients who want help meeting their nutrition goals to three products built around muscle and recovery. Each one is described below using Avastar’s own product information.

Because Avastar describes creatine as supporting muscle performance when combined with exercise, it fits most naturally once you are back to strength-based rehab or training. Talk with our team before adding any supplement, especially if you are pregnant or nursing, have a medical condition or take medications.

Muscle atrophy after surgery follows the same pattern as any injury: the repaired area is protected, so its muscles work less for a while. Rebuilding that strength is part of recovery. Our ACL reconstruction recovery guide explains that rebuilding quad and hamstring strength is not optional, because the muscles around the knee protect the new graft during the return to activity.

Many of the repairs our team performs, including rotator cuff repair, meniscus repair and ACL reconstruction, are done through small incisions with arthroscopic surgery, an approach designed to reduce recovery time and discomfort.

For joint-specific detail, including muscle loss after knee surgery, see our guides to rotator cuff surgery recovery and arthroscopic knee surgery recovery.

Our sports medicine team diagnoses and treats sports injuries using both non-operative and operative approaches, with the goal of helping you heal, regain strength and flexibility, and return to the activities you care about. Rehabilitation is personalized and focused on strength, mobility and function.

We treat the injuries that most often sideline active patients, from rotator cuff and ACL tears to ankle sprains and hamstring strains, and post-surgical rehabilitation is one of our core focus areas.

Recovery is not one thing. It is a system. Our care follows The BioMastery™ Philosophy, developed by Avastar® Health Systems and adopted by our practice, which organizes health around how the body heals: regenerative medicine and biological repair, movement and structural longevity, metabolic health, cognitive reserve, and recovery and adaptation. Protecting and rebuilding muscle after an injury draws on several of those pillars at once, so a plan may include one or more of these options:

Muscle atrophy after injury starts early, but much of that strength can be rebuilt. Following your rehab plan, staying active where you safely can and eating enough protein give your muscles a better chance to hold on to their strength while you heal.