The New Fitness Rules

How Many Rest Days Do You Need?

Old school: Wait 48 hours to recover after a strength workout.

New rule: If you've gone hard, you may need an extra day.

You've heard it plenty of times: Take at least a full day off between strength workouts to allow your muscles to rebuild and get stronger. But if you've taken a sculpting class that's left you shaking, press "Pause" a little longer. One study from Brazil determined that beginners who did four sets of 10 reps of biceps curls needed more than 72 hours of rest to recover. "If you start working those same muscles too soon, you could be compromising your results and even risking injury," explains exercise scientist Wayne Westcott, PhD, at Quincy College. That's because after your workout, your muscles have to work hard to rebuild those torn-down tissues, which is what will ultimately make you stronger and more sculpted. "Intensity is definitely more important than frequency," Westcott says. On those off-days, let cardio -- for instance, power walking, running, swimming, and cycling -- serve as an active recovery, so you can burn fat while allowing your muscles to rebuild.