Recent Research shows that 17 ounces of Watermelon juice consumed one hour before exercise leads to less muscle soreness after your workouts. There is no research on its effect as a post recovery drink. But I suspect it may work. Currently, there is good research on chocolate milk as a top choice as a muscle recovery drink.

Watermelon Juice: Potential Functional Drink for Sore Muscle Relief in Athletes
Martha P. Tarazona-Díaz, Fernando Alacid, María Carrasco, Ignacio Martínez, and Encarna Aguayo
Journal of Agricultural and Food Chemistry 2013 61 (31), 7522-7528