Strategizing your pre-gym fuel is serious business. You want to make sure not to slow yourself down (a big bowl of pasta right before a run is a recipe for some sluggish miles). And you want to take advantage of the fact that what lands on your pre-gym plate can boost your performance if done right. Well, after reading the findings of a new Frontiers In Physiology study, your new go-to might just be a big bowl of leafy greens. (See also: The Best Pre- and Post-Workout Snacks for Every Workout )
Researchers from the University of Leuven in Belgium wanted to see how nitrates—which are packed into leafy greens like spinach and arugula or root veggies like beets—might be able to directly boost athletic performance. To test it out, they had 27 people of average fitness do some sprint interval testing (short, intense cycling intervals) three times a week. The researchers split people into three groups: two groups trained at low oxygen levels to stimulate gym sessions at higher altitudes and one group trained under normal conditions. Of the two high-altitude groups, one took a 400mg nitrate supplement while the other popped placebos.
After five weeks of training, the athletes in the high-altitude nitrate group showed enhanced muscle fiber composition. Here’s why we care: performing intense workouts, especially the short, high-energy bursts you do in a HIIT class or while doing intervals on the treadmill, requires your muscle fibers to work hard and fast to sustain your power. The stronger your muscle fibers (and the longer they're able to last before getting tired), the better you're able to do that. The study didn't test for the effects of nitrate supplementation at regular altitudes so we can't extrapolate these specific results. But plenty of other studies have found that getting an extra dose of dietary nitrates can help your sweat sessions at any altitude, especially when it comes to powering you through an intense workout.
So how much spinach do you need to down to see the effects? The amount of nitrates in a single serving varies (nitrate concentration is heavily dependent on growing conditions, like the soil and fertilizer used on your spinach before it hits the farmer's market). But most studies estimate that you'd be able to get your 400mg in 2 to 3 cups of spinach. Whether you fuel up with a hearty salad or a pre-gym green juice, that's totally doable. Consider your juicing addiction warranted.