This is the optimal amount of time to rest between sets in order to build muscle, according to a trainer

Going to the gym, grabbing some weights, and ripping out your reps day after day is going to help you build up some serious muscles. There’s no doubt about it. But if you really want to up your game, there’s one easy tweak you can do during your workouts to ensure you’re getting the best possible results: watch the clock.

Whether you’re working on toning your arms with a pair of dumbbells or using one of the many machines, the easiest way to make sure you’re getting the most out of your reps is making sure you’re not underdoing (or overdoing) your rest period between sets. While most people tend to take just a few seconds before busting out another set, Betina Gozo, Nike master trainer, says it’s actually better to give your body much longer than that.

“It’s best to rest about one to two minutes between sets, maybe even three to five depending on how your body metabolizes carbs for food energy, how many reps you’re doing, and how heavy you’re lifting,” Gozo says. “When you’re strength training, your body is utilizing the ATP [adenosine triphosphate] created by the phosphocreatine system, and it uses phosphagens to give you energy and power your movements. When focusing on hypertrophy, one to two minutes is enough time for the phosphagen stores to replenish, and if you’re focusing on true strength with only one to three reps, your body will need a bit longer because of the increased load.”

So now you know exactly how long to wait between sets. But how many reps should you be doing? According to Gozo, it depends on which level you’re at in your strength training routine.

“If you’re in a foundational state of strength training, I always recommend higher reps [12 to 15] so that you can ensure your body is used to the movement patterns and moving correctly,” she says. “Once you feel confident in the movements and your goals are hypertrophy or bodybuilding, then shooting for six to 12 reps at moderate to heavy weight is ideal.”

Between your sets, don’t just grab your phone and scroll through Instagram to pass the time. Stay in the right headspace by grabbing a drink of water, getting in a nice stretch, foam rolling, or going on a short walk around the gym. Once the time is up, you’ll be ready to jump right back in again. And it won’t take long before all your hard works pays off.

Here’s how HIIT weightlifting can totally upgrade your routine. And while you’re at it, you might want to add these hanging leg raises into the mix, too, which strengthen your core and massage your hip flexors at the same time.