Carbohydrates, caffeine, beetroot juice, and creatine monohydrate (a popular muscle-building supplement) are all common pre-workout supplement ingredients that have been shown to improve exercise performance.
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., CSSD, 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.
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. Still, the authors caution that more research must be done on women and older individuals to make sure the results can be generalizable.