Athletes are often encouraged to build a rest day into their workout schedule. However, at some point, most athletes will need to take a longer break from their practice, whether to recover from an injury, illness, or exhaustion, or simply out of desire. What happens to the strength and endurance an athlete has built when he or she needs to take days, weeks, or months off?

Some research suggests that athletes may be able to take as many as three weeks off from training without significant losses to strength or muscle mass. Laith Jazrawi, MD, chief of the Division of Sports Medicine and orthopedic surgeon at NYU Langone Orthopedic Center, explains to MyFitnessPal that it’s not just muscle loss that decreases athletic performance after a long break, but also a dip in cardiovascular endurance.

Strength or weight training can be easier to rebuild, but Dr. Jazrawi emphasizes that it is important to restart exercise carefully and slowly after a hiatus to avoid tearing a tendon. “If someone goes back to lifting heavy weights immediately, that’s where they run the risk of tearing or breaking,” he says.

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