How long to rest for greater muscle, strength, and weight loss.

THE AMOUNT OF time you rest between sets can determine how quickly and efficiently you gain sizeand strength, and drop fat.

“When it comes to working out, timing is everything,” says Joe Stankowski, C.P.T., a trainer in Wilmington, DE. “The amount of time you rest between sets can have a major impact on how the exercise you’re doing affects your body.”

Rest too long and your workouts lose intensity; rest too little and you burn out too quickly.

Luckily, we have expert advice on how to tailor your rest periods to any fitness goal.

Rest periods for muscle gains

Studies have found that testosterone and growth hormone are produced in greater levels when you rest for short to moderate periods. The amount of time can vary a bit, depending on how many sets you’re going for and how heavy the weight is, “but 60-90 seconds between sets is a good guideline,” says Stankowski.

Rest periods for fat loss

“There are two great approaches to losing fat in your training,” says Stankowski, “and you should apply both in your program.” The first method is simply to burn as many calories as possible. Continuous exercise with little to no rest between sets (such as circuit training) is ideal.

The other highly effective weight-loss strategy is to alternate sets of unrelated exercises (such as squats and rows) that work the entire body, while still allowing enough rest to build muscle. For circuit workouts or higher-calorie-burning programs, keep your resting time between sets to 30 seconds or less. For alternating sets, however, you can bump that time up to 30-90 seconds.

Rest periods for strength gains

“Time is on your side when you’re training for pure strength,” says Stankowski. Both your muscles and central nervous system need time to recover from the effort of lifting very heavy weights. Failing to rest long enough will prevent you from lifting heavy on your next set—and even slow your recovery for your next workout. His advice: “Take three to five minutes of rest, then crank out another set.”

Rest periods for conditioning and efficiency

To build more muscle and finish your workout in less time, try cutting back on your rest periods by five to 10 seconds every week (don’t increase the weight). For instance, if you rested 60 seconds between sets this week, rest only 50-55 seconds next week. You’ll find that in a few weeks you can accomplish the same amount of work in much less time, increasing your overall conditioning dramatically.