Beets. They are a superfood. Roast some up for the week and you will have them for pre or post workout.

Several studies suggest that dietary nitrates like those found in beets may enhance athletic performance.

Nitrates appear to affect physical performance by improving the efficiency of mitochondria, which are responsible for producing energy in your cells (12Trusted Source).

According to one review, beetroot juice could enhance endurance by increasing how long it takes to become exhausted, boosting cardiorespiratory performance, and improving efficiency for athletes (13Trusted Source).

Promisingly, beet juice has also been shown to improve cycling performance and increase oxygen use by up to 20% (14Trusted Source, 15Trusted Source).