Novice marathoners who consumed a high percentage of their kilojoules in the days and morning before their first 42.2km race performed better than other new marathoners, according to an observational study published in the International Journal of Sport Nutrition and Exercise Metabolism.
Forty-six runners documented their food intake for the three days before and morning of their first marathon. Their average finishing time was 4:26, within a 42-minute window. According to the researchers, a small but significant part of the variance in times was attributable to pre-race diet, with those who consumed a moderate to high amount of their kilojoules as carbohydrates in the 24 to 36 hours before the marathon doing better than otherwise similar runners.
This might seem like no-duh news, but it’s real-world reinforcement of conventional carbo-loading theory, and has to do with something that all marathoners can control.
The key, of course, is to make sure you’re really carbo-loading – that is, effectively increasing your muscles’ glycogen stores – rather than just stuffing your face.