Muscles need fuel to function — that much is clear. But besides optimal pre- and post-workout nutrition, does the body ever need an extra energy boost mid-workout? Studies show there may be some benefit to refueling during a workout — but what and when isn’t the same for everyoneEffect of carbohydrate ingestion on sprint performance following continuous and intermittent exercise.Sugiura, K., Kobayashi, K. Medicine and Science in Sports and Exercise, 1998 Nov; 30[11]:1624-30..

Fuel for Thought — The Need-to-Know

Photo by Caitlin Covington

To run, to lift, to tumble — muscles first turn to carbohydrates (think: fruits, veggies, grains, and dairy) for energy whenever they’re present in the body. Muscles then store those carbohydrates as glycogen, (also available in the bloodstream and liver). But once the body gets moving, we start dipping into that stash — begging the question, are we sure there’s enough? Research suggests it all depends on the type and duration of exercise.

While shorter, low-intensity workouts (like a 15-minute stroll or a few core exercises during a commercial break) can usually make do with what’s stored naturally, an extra energy fix can be clutch during high-intensity, long-duration exercise. (Distance runners don’t stock those fanny packs with energy gels, chews, and jelly beans for nothing!) But why simple carbohydrates rather than a colossal protein bar or big ol’ whole-wheat bagel? Research shows that protein, fat, and complex carbohydrates (those with lots of fiber) can often take too long to digest to be effective fuel for the exercise at hand.

Refuel Right — Your Action Plan

From prepping the gym bag to perfecting that game face, we know there’s plenty to do before hitting the gym. Let’s see if a pit stop at the fridge (or vending machine) should be added to those to-do’s:

  • For cardio sessions under an hour: Drink responsibly. Sipping sports drinks intermittently has been shown to improve performance, though many experts warn not to overdo itCarbohydrate-electrolyte feedings improve 1 h time trial cycling performance. Jeukendrup, A., Brouns, F., Wagenmakers, A.J., et al. International Journal Of Sports Medicine, 1997 Feb;18[2]:125-9.. There’s no need for the extra sugar and calories when the body — if fueled properly all day long — can sustain performance without the boost.
  • For the big game: Keeps carbs close. It seems there’s some science behind Gatorade showcasing basketball and soccer mega-stars in action — drinking sports drinks during high-intensity exercise might in fact improve performanceCarbohydrate feedings during team sport exercise preserve physical and CNS function. Winnick, J.J., Davis, J.M., Welsh, R.S., et al. Medicine and Science in Sports and Exercise, 2005 Feb;37[2]:306-15.. See a doctor if you begin to sweat purple, though!

Keep in mind that a person’s metabolism, age, gender, and weight are all factors in the refueling game. And listening to the body is key: Light-headedness, nausea, and (excessive) fatigue should not come with the territory. Also, some anecdotal evidence shows that suddenly adding major doses of carbohydrates to a workout routine can result in discomfort, upset stomach, and diarrhea (ick, it’s true). Of course, everyone’s different, so a little trial and error can never hurt — just be sure to do it before game day! So whether we’re Kobe or just an average kid in the weight room, remember that optimal performance can’t happen without the right fuel before and during showtime.

The Takeaway

While moderate doses of simple carbohydrates might improve performance during cardio, not all exercise requires a mid-workout reboot.

What’s your favorite mid-workout snack? Tell us in the comments below!

This article has been read and approved by Greatist Experts Lindsey Joe and Joe Vennare.