With the possible exception of Bruce Banner's, muscles need a certain amount of rest in order to strengthen and grow. But while some say muscles need one to two days of rest to recover from exercise, this might not be a one-size-fits-all timeline.
All pain, no gain
Whether they're in it for health, happiness, or an upcoming vacation, many gym-goers want to look and feel a certain way - and fast. But in the process of strengthening the legs, chest, or any other muscle group, rest is just as important as reps.
And for many individuals, not taking an occasional rest day could lead to overtraining, which can mean decreased performance, elevated blood pressure, decreased immunity, disturbed sleep, and more.
Physical exercise, from lifting weights to running intervals, damages muscle fibers and can create that all too familiar soreness (and dread at the sight of stairs). Reduced range of motion, diminished muscle strength, and swelling are all common.
Inflammation happens as the muscles begin to heal. And it's during rest periods that muscles have time to recover and rebuild in stronger formations and increase in size. Peake JM, et al. (2017). Muscle damage and inflammation during recovery from exercise. DOI: 10.1152/japplphysiol.00971.2016
Yep, turns out that strength and muscle gains actually occur outside the gym, during periods of rest, not inside the weight room, according to the American Council on Exercise (ACE).
How long a rest is optimal?
As runner Christie Aschwanden writes in her bestselling book “Good to Go,”muscle pain can peak 24 to 72 hours after a hard workout. This discomfort is often called DOMS (delayed-onset muscle soreness), and it's why a minimum of 24 hours of rest is optimal after a workout.
The recovery period could extend to two to three days, or even a week, depending on the type and duration of the workout, according to research from the ACE Scientific Advisory Panel. Some professional athletes incorporate several weeks of rest after a competitive season.
Other factors include how intensely you work out, how often you work out, what you eat, whether your body is used to the particular movements, and the duration of exercise.
With so many mixed messages out there, one thing's for sure: Some amount of rest in your exercise routine is crucial to enhance muscle growth, and to avoid overtraining.
Try active recovery
Still, your muscles may not need to take a total break from movement in order to fully recover. Some experts say that active recovery - such as massage and light exercise - is often more effective than passive recovery, or complete rest.
Good, low-intensity exercise can include swimming laps, yoga, taking a walk or a light jog, an easy bike ride, even flying a kite - anything that gets your blood flowing without overworking your muscles.
You can also look to more mellow treatments to speed recovery, including icing, heating, static stretching, and massage therapy. (Don't forget about the trusty foam roller!)
One survey found that athletes used activities such as massage, cold water immersion, contrast baths, and stretching as recovery methods. Sleep, however, topped all other recovery methods in popularity. Crowther F, et al. (2017). Team sport athletes' perceptions and use of recovery strategies: A mixed-methods survey study. DOI: 10.1186/s13102-017-0071-3
An interesting finding from a small 2017 study: Active recovery and cold-water immersion showed equal effectiveness in reducing post-exercise inflammation and soreness. Peake JM, et al. (2017). The effects of cold water immersion and active recovery on inflammation and cell stress responses in human skeletal muscle after resistance exercise. DOI: 10.1113/JP272881
A review of the research, on the other hand, found massage to be the most effective post-exercise method for relieving soreness and fatigue. Dupuy O, et al. (2018). An evidence-based approach for choosing post-exercise recovery techniques to reduce markers of muscle damage, soreness, fatigue, and inflammation: A systematic review with meta-analysis. DOI: 10.3389/fphys.2018.00403
Another way to speed recovery: Pay attention to proper post-workout nutrition, including adequate amounts of protein.
There's no magic formula for optimal days of rest. Take your fitness level, intensity, frequency, and duration of activity into account, and look for signs that the body needs a break, like chronic muscle, joint soreness, or a noticeable drop-off in what your body can handle.
Be sure to recognize the difference between soreness and pain and, most of all, don't be afraid to take some time off.