For the millions of us out there who enjoy training and even racing with music, the quest for ideal running songs is an endlessly fascinating pursuit. Dr. Costas Karageorghis has spent two decades researching the correlation between music and athletic output. Not surprisingly, he discounts the impact music has on top-flight distance runners. 'The elite choose to focus on regulating their bodies and efficiency,' he says. 'They focus inwardly, not on music.' Yet for the rest of us, he sings a different tune. 'With non-elite athletes, I've found that listening to the right songs before and during exercise will not simply reduce feelings of tiredness, it will also increase performance levels by up to 20 percent,' he says.