Watermelon juice's reputation among athletes is getting scientific support in a new study, which found that juice from the summer favorite fruit can relieve post-exercise muscle soreness. The report in ACS' Journal of Agricultural and Food Chemistry attributes watermelon's effects to the amino acid L-citrulline.

Encarna Aguayo and colleagues cite past research on watermelon juice's antioxidant properties and its potential to increase muscle protein and enhance athletic performance. But scientists had yet to explore the effectiveness of watermelon juice drinks enriched in L-citrulline. Aguayo's team set out to fill that gap in knowledge.

They tested natural watermelon juice, watermelon juice enriched in L-citrulline and a control drink containing no L-citrulline on volunteers an hour before exercise. Both the natural juice and the enriched juice relieved muscle soreness in the volunteers. L-citrulline in the natural juice (unpasteurized), however, seemed to be more bioavailable — in a form the body could better use, the study found.