Although all fruits are healthy, some fruits are better than others for runners. The best fruits for runners include bananas, acai berries, oranges and blueberries. Because of their high potassium content, bananas not only provide fuel for your workout, but also prevent muscle cramps while running. Acai berries originate in the Brazilian rain forests and feature a significant amount of antioxidants. The berries also contain amino-acid complexes that support muscle contraction during exercise. Both blueberries and oranges contain a high vitamin C content, which helps repair muscle damage that might occur while running.