How does beet juice improve endurance?

Beet juice enhances endurance primarily by increasing nitric oxide levels, which causes vasodilation. Vasodilation improves the delivery of blood to muscles and other tissues during extended periods of endurance work. Although individual reactions to beet juice can vary, it is recognized for enhancing the performance of moderate to long-duration endurance activities because it is not a stimulant and does not interfere with sleep 1 2.