We all love that extra zing a dose of caffeine can provide when we’re feeling a weary. A jolt of pre-workout caffeine just before you hit the gym can put some extra pep in your step and help you reach your goals. That’s why it’s a common ingredient in sports supplements. Here’s how it affects your performance:

ACT FAST

When your brain is on point, so is your body. In addition to giving you energy, caffeine boosts mental alertness and sharpens focus, which can speed up your reaction time and enhance your overall performance as you push through heavy lifts. Caffeine is an effective energy-boosting supplement that works best when taken one to two hours before your workout. That timing ensures you will have peak levels of caffeine in your bloodstream right when you hit those machines at the gym.

GO LONG

The infusion of energy caffeine provides can be sustaining enough to power you through longer bouts of exercise. That can translate to better endurance on the treadmill, on the pavement and in the weight room. If your goal is to hammer out extra miles or push through extra sets and reps, caffeine can help you push a little longer before you tap out.

BOOST YOUR BURN

If you’re working to get lean and sculpted, caffeine can be a great ally. When taken in doses between 100 to 400 milligrams, it has thermogenic properties—meaning it revs up your metabolism, allowing you to torch maximum calories during your workout and throughout your day. An eight-ounce cup of coffee contains about 85 milligrams of caffeine, and studies have shown that as little as one to two cups of caffeinated coffee per day can help you burn extra calories. If java isn’t your thing, or you want additional performance benefits, pre-workout supplements that contain caffeine are a great way to get an energy shot along with other helpful nutrients like protein and amino acids.

Since caffeine has diuretic properties, too much could counteract your goal of maintaining fluid balance. If your pre-workout supplement contains it, be sure to drink plenty of caffeine-free fluids before, during and after you exercise. And, if you’re taking other sport supplements, be sure to check the ingredient labels so you can make sure you’re not getting more than 400 milligrams of caffeine a day. Any more than that and you might feel jittery and anxious.