Daily consumption of this vegetable can increase exercise performance. Here's what you need to know.
You Need to Know About Nitrates
Nitrates are chemicals that have been linked to a bunch of different physiological functions in cells, including the creation of mitochondria and the repair of skeletal muscle. They've also been shown in several studies to improve exercise performance.
However, very few studies have been done to see if nitrates improve the strength of muscle contractions. That's what makes a new Italian study so interesting.
The researchers recruited 7 athletically active male students and measured their performance on two occasions. Six days before the first test, the students ate a diet with normal amounts of nitrate. Six days before the second test, students tripled their blood nitrate levels by eating foods rich in nitrates (spinach, collard greens, and bananas).
The two tests involved cycle sprints (a measure of moderate intensity aerobic performance) and leg extensions (a measure of high-intensity intermittent muscular performance).
After ingesting a nitrate-rich diet, cycle sprints showed that the students used less oxygen when cycling at a moderate intensity. In other words, their sprint performance improved because they used less energy.
The nitrate-rich diet also enhanced muscle work, as measured by an isometric leg extension machine where the students were required to try as hard as they could to push against an immovable object. Each rep lasted 3.5 seconds, with 10 seconds of rest between each rep. The "set" was judged to be over when the students could no longer push at least 75% as hard as they could on the first rep.
On the control diet, students could only squeeze out a mean of 32.5 reps. On the nitrate-rich diet, they squeezed out a mean of just over 47 reps.
How to Use This Info
It's probably no secret that taking in a higher level of nitrates contributes to athletic performance, but research showing that it contributes to high-intensity muscular contractions is rare.
Of course, supplement companies have long claimed that supplemental nitrates increase exercise performance by "increasing blood flow," but there doesn't seem to be much evidence of that. Additionally, it looks like nitrates obtained through foods raise blood levels to a much greater degree than supplemental forms.
As far as specific foods, the study involved feeding the subjects daily servings of spinach (40 grams, or about 1 cup), collard greens (80 grams, or about 1 cup), banana (140 grams, or one large banana), and pomegranate juice (0.5 liters). However, there are lots of foods that are high in nitrates, including broccoli, walnuts, cranberries, cocoa, shrimp, eggplant, arugula, and many others.
You don't have to eat these same foods if you want to increase performance before a particular event like a race or some other endurance contest. Just make yourself a big, honkin' daily salad, starting about a week out before the event. Make sure to use ingredients like arugula, spinach, walnuts, and maybe cranberries. You might also have a banana at a later point in the day.
Alternately, if you're a lifter who just wants to enjoy perpetually high nitrate levels so that you can ride that exercise as long as you can, take the easy way out and just make it a practice to eat one banana a day, take a daily dose of curcumin (which has been found to increase the conversion of nitrates and nitrites in plasma to nitric oxide), and add spinach to as many meals as you can.
Spinach is an innocuous vegetable as it has a benign taste and "melts" down to practically nothing when you add it to scrambled eggs, soups, or stews. You can also throw it into a pan of whatever meat you're cooking and it'll mind its own business while it cooks down to a smattering of green.
- Simone Porcelli, et al. "Effects of a Short-Term High-Nitrate Diet on Exercise Performance," Nutrients 2016, 8(9): 534.