Training for a Big Race? Hold the Carbs at Dinnertime

Many athletes eat large helpings of carbs the night before a big race to make sure they have enough fuel for the next day. But research has found that loading up the night before may end up slowing you down. Published in Medicine & Science in Sports & Exercise, the study put 21 experienced triathletes on a new training and diet program for four days every week, for three weeks. The training portion of the program consisted of two parts: In the afternoon, all the athletes performed high-intensity interval training, designed to increase fitness and deplete their bodies’ carbohydrate stores; then, prior to breakfast the next morning, the athletes cycled moderately for an hour on stationary bikes. On each training day, all the athletes ate the same amount of carbs, but with one difference: half the athletes ate their carbs throughout the day, including during workouts (a "standard sports diet"); the other half ate their carbs only during breakfast and lunch (a "sleep-low diet"), to limit their bodies’ ability to use carbohydrates for energy. On non-program days, athletes were allowed to eat what they wanted and train at an easier pace. Researchers found that:

  • The group eating the sleep-low diet finished a 10K run about 75 seconds faster at the end of the study than they did at the beginning of the study, while the group eating the standard sports diet showed no improvement.
  • The group eating the sleep-low diet also showed greater improvements in muscle efficiency and performance during morning cycling over the course of the trial, and lost more body fat, compared with the standard sports diet group.
These findings suggest that timing is everything when it comes to carb loading. If you're getting ready for a race, it might be a good idea to double up on healthy carbs like whole wheat bread, oats, brown rice, barley, and quinoa in the morning and afternoon, and then skip them in the evening to fuel your need for speed on race day.


Source: Medicine & Science in Sports & Exercise


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