Watermelon is rich in the amino acid L-citrulline, which converts to L-arginine and promotes nitric oxide production. Nitric oxide is a gas released that opens blood vessels and improves blood flow. It helps clear away lactic acid buildup so you can workout longer and harder.
Plus, watermelon, as the name implies is packed with water- 92% water, making it extremely hydrating.
Snack on watermelon as a pre-workout snack, add some watermelon juice to your water, or enjoy a few slices during an endurance session.