The ancient Greeks held the belief that plentiful sun exposure was vital for physical performance, and they required Olympian athletes to bathe in the sun as part of their training. A growing body of research indicates that the sunbathing practices of these ancient athletes were well-informed. Sun exposure influences a wide variety of physiological processes that affect athletic performance, including testosterone and nitric oxide production, circadian rhythms, alertness, skeletal muscle function, and vitamin D status. Read on to learn how safe sun exposure can help you reach your highest athletic potential.