Pre-workout supplements have been studied on a bunch of workout metrics, including strength, power, and endurance, as well as time it takes to fatigue, and perception of effort—or how hard it feels like you’re working during a given task.
For those reasons, people may choose to take pre-workout before a variety of workouts, from trying to increase their 1-rep max on the back squat, power through an interval-heavy running workout, or simply have enough gas left in the tank to crank out the final burpee in a HIIT class.
But does pre-workout actually do these things? It’s a mixed bag: Some pre-workout ingredients are well studied and can actually help improve your performance—those are the ones we’ll cover more in depth, below—but the majority of pre-workouts probably won’t. The ones that don’t work are ineffective at best, and dangerous for your health at worst. Here’s what you need to know.
What are the benefits of pre-workout?
There are a few common pre-workout supplement ingredients that have been shown to improve exercise performance, including carbohydrates, caffeine, beetroot juice, creatine monohydrate, and beta-hydroxy-beta-methylbutyrate (HMB). Here’s a brief overview of what the research indicates they might do for you.
1. Carbohydrates
The reason carbs help is pretty obvious—they’re your body’s go-to source of energy and what experts recommend eating before a workout to properly fuel.
“Evidence supports a range of carbohydrate uses for various athletic applications, from taking in 30 to 60 grams per hour during endurance events to simply rinsing the mouth with a carbohydrate solution before sprint events,” Georgie Fear, R.D., C.S.S.D, a board-certified sports dietitian with One by One Nutrition, tells SELF.
After all, when exercising—especially at high intensities with boot camps, indoor cycling classes, and lifting sessions—your body uses blood glucose and glycogen (stored carbs) as its main energy source. So topping off your levels before you start your workout can help increase energy availability and performance, she says.
2. Caffeine
Meanwhile, caffeine obviously is a stimulant known for boosting energy and alertness, and research shows it can help improve sports performance too. Many of the studies have been done on small sample sizes, but there’s actually a lot of research backing caffeine’s ability to improve workout performance. In fact, a 2020 review of 21 previously published meta-analyses on caffeine concluded that supplementation of it may enhance aerobic endurance, muscle strength, muscle endurance, jumping performance, and speed. While the exact amounts varied per study, you’d likely need to take between three to six milligrams of caffeine per kilogram of bodyweight (that’s 204–408 mg of caffeine for a 150-pound person) for it to work as a performance aid, the review says.
Still, the authors caution that more research must be done on women and older individuals to make sure the results can be generalizable.
3. Beetroot juice
Beetroot juice is a little less researched, but a 2017 review on relevant studies found that it has consistently been shown to increase the body’s levels of nitric oxide—a natural vasodilator that expands blood vessels and increases blood flow—and improve cardiovascular performance. Plus, a 2020 study published in the International Journal of Sports Physiology and Performance found that people who took a beetroot supplement before a 30-second, all-out cycling sprint test produced more power and felt lower rates of perceived exertion than those who didn’t take the supplement. While it’s important to note that research on beets is still pretty new, and most studies are small, so far all of them show promising results.
4. Creatine monohydrate
Creatine monohydrate is often included in pre-workout formulas. Creatine is a derivative of three amino acids that’s naturally produced in the body and stored in the muscles as a source of quick energy. Creatine can help you exert more effort during your workout, especially for high-intensity intervals, Ansari explains, and in turn support greater muscle growth.
