Find out the truth about the benefits, safety, and downsides of pre-workout supplements, according to experts.


By Mallory Creveling
Updated December 02, 2020

You may have heard your CrossFit or HIIT class friends refer to downing some "pre" before they hit the gym. Or perhaps you've seen companies advertising products meant to power you through a tough sweat. These pre-workout supplements have gained steam lately, as many people tout their energizing effects.

Because of the increase in popularity, more science has looked into the benefits and whether these pre-workout mixes actually have a positive payoff on performance. With any supplement, though, there could be some risks. Ahead, experts deliver the full ~scoop~ on pre-workout powders and pills.

When a Pre-Workout Supplement Can Give You a Boost

Science offers conflicting research about whether pre-workout supplements improve performance, and most studies (on the positive and negative side) involve fairly small test groups. One study found that while participants reported higher energy and concentration, the physical payoffs were lacking. Meanwhile, another study showed better energy, along with increased muscular endurance and anaerobic capacity.

The best research focuses on individual ingredients, rather than the combo that comes in a typical pre-workout supplement.

Caffeine: "The most common ingredient in pre-workouts is caffeine," says Pam Bede, R.D., a sports dietitian with EAS Sports Nutrition. "That's because this familiar ergogenic aid has been used by athletes with the hopes of improving endurance, delaying fatigue, and even lowering the rate of perceived exertion (how difficult you perceive the workout to be)." For example, several studies show there are benefits of caffeine on strength and power outputs. Bede says the optimal dose of caffeine is .9 to 1.4 mg per pound of body weight. For example, a 150-pound person would require about 135 to 200 mg of caffeine about 20 minutes before a workout. (FYI, that's less than a small cup of coffee at most cafés.)

Branched Chain Amino Acids (BCAAs): These popular pre-workout ingredients are the building blocks of protein and are meant to protect glycogen stores in the muscles (so you can work out longer), and they may also help with recovery, says Bede. Science backs this up: One study supports the role of BCAAs in recovery and the building of muscular anaerobic power (your body's ability to generate force). Other research found that BCAA supplementation helps maintain muscular performance. (Beta-alanine, specifically, is included in many pre-workout products.)

Nitric Oxide (NO) Boosters: You might also find nitric oxide boosters in a pre-workout mix. (These may be listed under names such as L-arginine, L-citrulline, or L-norvaline.) These help with blood flow and nutrient and oxygen delivery to the muscles, says Bede. This can contribute to giving your muscles a "pumped up" look and feeling. One research review says the nitrate from beetroot juice can improve cardio endurance and time to exhaustion. Keep in mind that instead of a supplement, you could just go straight for the beet juice pre-workout. Though the exact amount you need depends on your size, Bede suggests aiming for 300 to 500 mL of the juice or about 400 to 500 mg of a nitrate supplement. (Here's more on nitric oxide and how to get more without supplements.)

Protein and Creatine: Finally, protein (including creatine) is a big draw for many supplement takers — though that need isn't usually addressed in a pre-workout product. You're more likely to find protein in "recovery" supplements (or straight-up protein powder) than in pre-workout blends, although the BCAAs in pre-workout supplements do provide protein-building amino acids. Wayne Westcott, Ph.D., professor of exercise science at Quincy College, does call out protein (about 20 to 25 grams just before or just after a strength session) for scientifically helping women gain lean muscle mass and lose body fat — though that can be via a supplement or whole-food source. Creatine, on the other hand, can be found in some pre-workout supplements (or sold separately) and can be used to improve performance during high-intensity workouts, as previously reported in this guide to pre-workout and post-workout supplements.

Credit: Shutter2U/Getty

Why You Have to Be Careful with Pre-Workout Supplements

Now, let's talk safety. As with all supplements on the market, pre-workout products aren't regulated by the U.S. Food and Drug Administration (FDA). That means manufacturers don't need to test the safety of the specific product. And the amount of each ingredient could vary from package to package. (Related: Why This Dietitian Is Changing Her View On Supplements)

Opting for a reputable brand — one that has a stamp of approval from a third party, such as the Good Manufacturing Practices or GMP stamp, which ensures a dietary supplement contains everything it says it does — is a good way to know if you're getting a safe pre-workout product, says Bede. However, these stamps aren't 100 percent foolproof, and you'll still want to check the ingredient list to note whether the pre-workout supplement has more caffeine than you can handle or a long list of ingredients you've never seen before.

If you're sensitive to caffeine, you should be especially skeptical of pre-workout supplements, adds Bede. Most contain a variation of the stimulant to provide an energy boost. For some people, this can cause shaking, rapid heart rate, and other side effects that could actually hinder your workout. She also tells her clients to stay away from bitter orange, synephrine, and anything with a chemical makeup similar to ephedra and ephedrine — an ingredient banned by the FDA for causing serious side effects, such as heart conditions. (For a list of ingredients to look out for, check out the FDA's page on supplement ingredients.)

Consumers are paying more attention to what's in their food and supplements (hi, clean eating) and some brands are taking note and prioritizing high-quality ingredients and easy-to-read labels. Take The Go Life, a nutritional supplement meant to improve your physical performance and cognitive focus, for example: brand cofounder and former pro cyclist, Alex Cesaria, says they pay particular attention to their ingredients because consumers have become so in-tune with product labels. Cesaria and his team also decided to make their supplement in pill form to help regulate the amount of each ingredient. "When you scoop a powder, it's hard to know exactly how much you're getting," says Cesaria. "The precise delivery is something we find important."

One other safety precaution when considering supplements: "Do not take the advice of salespeople in supplement stores; these people are not nutrition experts," says Torey Armul, R.D.N., a sports nutritionist and spokesperson for the Academy of Nutrition and Dietetics. "Consult with a registered dietitian to create a safe, effective, and tailored fueling plan to meet your needs."

The Best "Natural" Pre-Workout? Whole Foods

You can find many of the ingredients in pre-workout supplements — the ones that research has shown to improve performance, such as caffeine or nitric oxide — in real foods, too. Plus, with those real foods, you also get other good-for-you nutrients. (Here are a ton of pre-workout snack options.)

"I recommend a 'food first' approach for both recreational and elite athletes who are looking to fuel their workouts," says Armul. "Real foods, rather than powders or supplements, are ideal because they offer the best variety of macro and micronutrients, tend to be easiest to digest, and are more palatable."

Armul recommends keeping it simple with a snack one to two hours pre-workout, making sure endurance athletes get a heavy serving of carbohydrates and weightlifters get a combo of carbs and protein. Watch the fiber and fat, cautions Armul, as you'll digest those more slowly, which could lead to digestive discomfort. (Related: 20 Foods You Shouldn't Eat Before a Workout)

So Should You Take a Pre-Workout Supplement?

If you're a recreational exerciser, you probably don't need a pre-workout supplement. Beet juice, whole-food protein sources, and natural caffeine sources such as matcha or coffee can likely provide the benefits you're looking to achieve when taking a pre-workout supplment — but without the risk.

If you do choose to grab a pick-me-up pre-workout, do your research. "Don't just turn to the product's website or Amazon page for info," says Bede. "Really look into each ingredient to make sure it's safe, effective, and will improve your performance." (And when in doubt, consult a doctor or a dietitian before popping any pre-workout powders or pills.)