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.

All Pain, No Gain — Why It Matters

Whether we’re in it for health, happiness, or the holidays, 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.

Physical exercise, from lifting weights to running intervals, damages muscle fibers, creating the 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 can also increase in size. (Go ahead, it’s OK to look in the mirror!)

While it hasn’t been widely proven, some research suggests that because muscle soreness can peak two days post-exercise, a minimum of 48 hours’ rest is optimal to allow recovery and prevent injury— at least among the soldiers and competitive athletes who were studied The effects of exercise-induced muscle damage on cycling time-trial performance. Burt, D.G., Twist, C. Department of Sport and Exercise Sciences, University of Chester, Chester, United Kingdom. Journal of Strength and Conditioning Research, 2011 Aug;25(8):2185-92. Muscle damage: nutritional considerations. Evans, W.J. USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA. International Journal of Sport Nutrition, 1991 Sep;1(3):214-24. . But for the rest of us, there may be other factors to consider, starting with age, which often means slowed muscle recovery and growth. Fitness level can also weigh in, since fitter people tend to recover faster from familiar activities. Though there may be no consensus on optimal rest time, one point seems certain: Periodic rest is good for the muscles.

Keep on Pushin’? — The Answer/Debate

Still, several studies question the notion of complete rest for muscle groups. One study found low-intensity post-workout exercise— such as swimming laps— can increase muscle relaxation, which benefits recovery Effect of incorporating low intensity exercise into the recovery period after a rugby match. Suzuki, M., Umeda, T., Nakaji, S., et al. Hirosaki University, School of Medicine, Zaifu-cho 5, Hirosaki 036-8562, Aomori, Japan. British Journal of Sports Medicine, 2004 Aug;38(4):436-40. . Other research suggests muscles can work to full capacity even while in the recovery stage (drill sergeant trainers optional) Muscle damage and muscle remodeling: no pain, no gain? Flann, K.L., LaStayo, P.C., McClain, D.A. et al. Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ. Journal of Experimental Biology, 2011 Feb 15;214(Pt 4):674-9. Plyometric exercise increases serum indices of muscle damage and collagen breakdown. Tofas, T., Jamurtas, A.Z., Fatouros, I., et al. Department of Physical Education and Sport Sciences, University of Thessaly, Greece. Journal of Strength and Conditioning Research, 2008 Mar;22(2):490-6. . Some elite weightlifters take almost no rest days and gradually teach their bodies to adapt to nearly constant stress (talk about a hard day’s work!).

On the flip side, more mellow treatments are prescribed to speed recovery, including icing, heating, static stretching, and massage Effect of postexercise recovery procedures following strenuous stair-climb running. Robey, E., Dawson, B., Goodman, C., et al. School of Sports Science, Exercise and Health, The University of Western Australia, Crawley, Australia. Research in Sports Medicine, 2009;17(4):245-59. . Another way to speed recovery: Pay attention to proper post-workout nutrition, including adequate amounts of protein Postexercise muscle glycogen recovery enhanced with a carbohydrate-protein supplement. Berardi, J.M., Price, T.B., Noreen, E.E., et al. Exercise Nutrition Research Laboratory, Faculty of Health Sciences, School of Kinesiology, The University of Western Ontario, Ontario, Canada. Medicine and Science in Sports and Exercise, 2006 Jun;38(6):1106-13. .

The bottom line: There’s no magic formula for optimal days of rest. So take those birthdays and fitness levels into account, and look out for signs that the body needs a break like chronic muscle or joint soreness and impaired physical performance. Be sure to recognize the difference between pain and soreness, and most of all, don’t be afraid to take some time off.

Photo by Justin Singh

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