With the exception of people named Bruce Banner, muscles need a certain amount of rest in order to strengthen and grow. But while some sources suggest muscles need 48 hours or more to recover from exercise, there might not be a one-size-fits-all timeline.
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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 a feeling of soreness (and dread at the sight of stairs). But during rest periods, muscles have time to reconstruct (or recover) in stronger formations and increase in size. Yep, turns out that strength and muscle gains actually occur outside the gym, during periods of rest, not inside the weight room.
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Some research suggests that because muscle soreness can peak two days post-exercise, a minimum of 48 hours of rest is optimal to allow recovery and prevent injury—at least among the competitive athletes who were studied. Other experts suggest resting up to 72 hours between workouts if you're an exercise newbie, while some say eight hours of good sleep is enough for your body to recover.
Finally, one meta-analysis determined that for optimal strength development, one to two rest days between sessions is ideal for beginners training three days per week and experienced exercisers training two days per week.
Still, there are other factors to consider when it comes to determining adequate rest. Those who are older, for instance, may experience slowed muscle recovery and growth. Other factors include how intensely you work out, how often you work out, what you eat, 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 keep symptoms of overtraining at bay.