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How long does it take to regain muscle after bed rest?

Bed rest, also known as immobilization, can lead to significant loss of muscle mass and strength. The rate of muscle loss is highest in the first few weeks of bed rest but can continue more slowly over longer periods of immobility. Several factors affect how quickly muscle mass can be regained after a period of bed rest, including the duration of immobilization, the initial level of fitness, age, nutrition and exercise habits. With proper nutrition and exercise, most healthy adults can regain most of their muscle strength within 2-6 months after 1-3 months of bed rest.

How much muscle is lost during bed rest?

During bed rest, muscle breakdown occurs rapidly while muscle building slows down or stops. In the first 1-3 weeks of bed rest, muscle mass declines at a rate of 0.5-1% per day. Without any muscle contraction, protein synthesis can decrease by nearly 50% while protein breakdown increases by 90%.

Several studies have quantified the losses in muscle mass and strength with bed rest:

  • After 17 and 52 days of bed rest, young men lost 12-17% of muscle mass from their legs and arms.
  • Following 90 days of bed rest, subjects lost 15% of their baseline muscle volume.
  • Isometric knee extension strength decreased by 20% after 20 days and 50% after 90 days of bed rest in healthy adults.
  • After 5 weeks of bed rest, peak torque of knee extensors declined by 20-50%.

The rate of muscle loss is highest in the first month of bed rest but continues to decline at slower rate over longer periods of immobilization as muscle tissue is lost. However, even after 3-6 months of continuous bed rest, muscle continues to deteriorate.

Factors affecting muscle regain after bed rest

Several factors impact how quickly muscle mass and strength can recover after a period of immobilization or bed rest:

Duration of bed rest

The longer the duration of immobilization, the more muscle is lost and the longer it takes to recover. With short durations up to 2 weeks, muscle mass and strength can recover within 2-4 weeks with proper training. But with more prolonged bed rest of 3 months or longer, it can take many months to regain normal muscle function.

Initial fitness level

People who are fitter initially tend to lose less muscle with bed rest. Trained individuals also rebuild muscle more efficiently after immobilization. Athletes recover their strength and muscle mass faster than untrained individuals.

Age

Younger adults have better rates of muscle protein synthesis. So they tend to lose less muscle mass during bed rest and regain it more quickly afterwards. Older adults have blunted muscle plasticity so they have greater losses and slower recovery of muscle after immobilization.

Nutrition

Consuming adequate calories and protein is essential to provide building blocks to rebuild muscle. Protein supplementation along with calories can help accelerate muscle regrowth after bed rest.

Exercise

Early reintroduction of exercise, especially resistive exercise, is key to regaining muscle mass after bed rest. The specific exercise program followed makes a major difference in the rate of muscle rebuilding.

Injuries or illness

Injuries, surgery or illnesses that require bed rest can delay recovery and rehabilitation. Underlying health conditions may limit one’s ability to rebuild muscle through exercise after immobilization.

How long to regain muscle after 1 week of bed rest?

For short term disuse of less than 2 weeks, most muscle mass and strength can be recovered in 2-4 weeks with proper rehabilitation. However, the rate of recovery depends on the factors discussed above.

In one study, active young men who underwent 1 week of bed rest lost 3.7% of their quadriceps muscle volume. With supervised resistive exercise 3 times a week for 3 weeks, they recovered 96% of their baseline muscle volume and 100% of strength.

Another study found 1 week of bed rest resulted in 7-10% decreases in muscle protein synthesis in the legs. Healthy active adults recovered their normal muscle protein synthesis levels within 2 weeks of returning to normal activity.

So for most young, active adults, 1 week of bed rest leads to small muscle losses that can recover within 2-4 weeks with proper nutrition and training.

How long to regain muscle after 2 weeks of bed rest?

With 2 weeks of bed rest, muscle loss accelerates, with decreases in muscle mass up to 10%. More intensive training may be required to rebuild muscle tissue after this duration of immobilization.

In one study, active adults underwent 2 weeks of bed rest. They lost 5-10% of muscle mass in their legs. With 6 weeks of cycling exercise for 30 mins per day, they recovered only 51-58% of their quadriceps strength and muscle size.

In another trial, older adults had a 10% decrease in thigh muscle cross sectional area after 2 weeks of bed rest. With 8 weeks of supervised resistive training, they recovered 96% of their baseline muscle size.

So while young active adults may recover within 4 weeks, it can take 6-8 weeks to regain most of the muscle lost after 2 weeks of immobilization for middle-aged and older adults.

How long to regain muscle after 1 month of bed rest?

One month of continuous bed rest can result in losses of 10-15% of muscle mass, with significant reductions in muscle strength. It takes several months to rebuild muscle tissue after this duration of immobilization.

In NASA bed rest studies, subjects underwent 30 days of strict bed rest. They lost 11-17% of muscle mass in their legs. In one study, it took them 12 weeks after bed rest to fully recover their leg press and leg extension strength with intensive resistive exercise.

For older adults, the process takes longer. After 28 days of bed rest, older men lost 5-10% of their quadriceps muscle mass. It took 16 weeks of supervised resistive training for them to regain 96% of their baseline muscle size.

So for most adults, it takes about 2 to 4 months to recover the muscle mass and strength lost after 1 month of bed rest with proper exercise.

How long to regain muscle after 90 days of bed rest?

Prolonged bed rest of 90 days results in severe muscle wasting, with losses of up to 30-50% of muscle size observed in studies. Full recovery can take over 6 months with intensive rehabilitation.

In one trial, healthy adults underwent 90 days of bed rest. They lost 29% of their muscle volume and 34% of strength after 90 days. After 140 days of rehabilitation, they recovered only 80% of their baseline muscle volume and 86% of strength.

Another study found 90 days of bed rest resulted in a 48% decrease in knee muscle volume in older adults. With 52 weeks of resistive training, they recovered 96% of their muscle size prior to bed rest.

So after 3 months of continuous bed rest, even a full year may be required to fully regain normal levels of muscle mass and function, particularly in older adults.

How long to regain muscle after 6 months of bed rest?

After extended immobilization of 6 months or longer, muscle tissue may be largely replaced by fat and fibrous tissue. Significant effort is required to retrain the body to rebuild muscle after such severe atrophy.

One study found 6 months of bed rest resulted in a 54% decrease in muscle fiber cross-sectional area. Three months of rehabilitation recovered only one-third of the loss. After a full year of training, muscle size was 90% of baseline.

Another 6 month bed rest study observed a 45% reduction in thigh muscle volume. Two months of resistive exercise helped recover only 64% of this volume. Only after a year of supervised training was 97% of muscle size regained.

So after 6 months or more of continuous bed rest, it can take a year or longer to achieve near complete recovery of muscle mass and strength.

Nutrition for rebuilding muscle after bed rest

Consuming adequate protein and calories can help accelerate muscle regrowth after bed rest or immobilization. Some guidelines include:

  • Protein intake: 1.2 – 1.5 g/kg body weight per day
  • Evenly distribute protein at meals and snacks throughout the day
  • 20-40 grams of protein per meal maximally stimulates muscle protein synthesis
  • Leucine rich proteins (whey, eggs, beef, fish) optimally support muscle regrowth
  • Carbohydrates: sufficient to fuel exercise and activity
  • Fat: 20-30% of total calories

Ensure adequate calories to prevent ongoing weight/muscle loss. Weight gain often occurs during rehabilitation, which may help drive muscle regrowth.

Exercise program to regain muscle after bed rest

Exercise, especially resistive strength training, is critical for rebuilding muscle after periods of unloading. Some general tips include:

  • Start exercise as soon as feasible after medical clearance
  • Focus initially on activating muscles prior to loading
  • Use moderate loads (~60% 1RM) for higher volumes (3-4 sets x 10-20 reps)
  • Emphasize large muscle groups (quads, hamstrings, chest, back, glutes)
  • Progress load gradually over weeks as strength improves
  • Aerobic exercise helps maintain cardiovascular fitness
  • Stretching promotes flexibility and mobility

A proper periodization program that cycles volume and intensity maximizes muscle rebuilding.

Conclusion

The duration of bed rest or immobilization has a major impact on the time course of muscle rebuilding. While short term disuse of 1-2 weeks can recover within weeks, long term bed rest of months or more may require a year or longer to regain normal muscle mass and strength after atrophy. Proper nutrition and exercise programming accelerates the process of muscle regrowth after disuse.