In my last article, I discussed the tempo at which you should strength train for optimal success and for injury prevention as well. This week, I am adding the rest component to the strength-training workout.

When you’re strength training, there’s more to consider than reps and how much weight to pick up. Another important factor in improving: rest between sets.

The amount of break time you take determines how your muscles adapt to the movement, says Carwyn Sharp, Ph.D., chief science officer for the National Strength and Conditioning Association. “Matching rest periods and intensities places the appropriate amount of stress on the muscles and their energy systems,” he says.

Besides working your muscles in different ways, the breather you take between exercises correlates to injury prevention. “If you wait too long to move your muscles again, they become cold, which increases the risk of injury due to muscle damage,” says Peter McCall, exercise physiologist and American Council on Exercise trainer. “On the other hand, if you don’t rest long enough, your body can’t replenish the muscles’; energy efficiently, so you’re exercising in a fatigued state. This can lead to poor form and therefore injury.”

In my experience, most of my clients want to shed extra weight and tone, sculpt and strengthen their muscle, not add extra mass like a body builder. For these clients, rest periods are less than 30 seconds.

Fitting into a smaller pants size involves a combo of many approaches, Sharp says. Eliminating rest periods and pushing through a 30-minute workout without stopping will certainly help you torch more calories, a key to losing weight—but that’s not the only factor.

“Maintaining or increasing muscle mass and strength are also important, because they allow your body to burn more calories while at rest”; he explains. The more muscle you have, the higher your calorie burn throughout the day, even when you’re sitting on the couch. If you’re new to weight training, you can also try the plan below.

If your goal is to get stronger and faster and add muscle mass, then I recommend pumping heavy iron—(85 percent or more of the max weight you can lift); you should rest a minimum of two minutes between sets. This will maximize your strength gains. Even better, waiting three minutes will help lower your perceived exertion levels or how hard you think you’re working, while still boosting your stamina.

“The rest between sets determines your ability to sustain the heavy weight for subsequent sets,”; says Estevao Scudese, study author and associate researcher at Federal University of Rio de Janeiro in Brazil. This study also supports resting longer to lift more later.

So what should you do during those minutes of rest? Sit and relax, especially if you focused on your legs. Another study found that rest intervals are particularly important when working major muscle groups, like those in your lower body. If you worked your shoulders, arms, or chest and prefer not to take a seat, Butler suggests walking around the room. Another option: Shake out your limbs to release any tension, and help keep yourself calm and loose between sets.

For those who just can’t squeeze in the necessary wait time, try doing super sets. This involves alternating exercises that focus on different muscle groups. For example, do push-ups followed by deadlifts—the upper body can then rest while you work your lower half and vice versa.

One more note about lifting heavy weights: It’s a great (safe!) idea to have a spotter. Whether that’s a fellow lifter or a trainer, knowing a spotter is there can put you at ease mentally, allowing you to complete reps with better form.

Of course any of these outcomes will improve your health—strength, muscle mass, endurance, and weight loss are all positive outcomes. So if you end up cutting your rest a little shorter or making it longer than planned, don’t fret: You’ll still gain benefits. Just keep in mind that the heavier the weight you’re lifting, the longer you should wait to pick it back up.

Even more important: Listen to your body. If you feel too tired or your heart rate is too high to start another round, give yourself a few extra seconds. If you’re feeling strong and energized, make your rest time a little shorter that day.