A carb loaded diet

To avoid running out of carbohydrates for energy, some endurance athletes like
long-distance runners, swimmers and bicyclists load their muscles with glycogen
by eating extra carbohydrates in combination with doing depletion exercises
several days before an event:
First exercise to exhaustion. Your workout
must be identical to the upcoming event to deplete the right muscles.
Then
eat a high-carbohydrate diet (70-80 percent carbs, 10-15 percent fat, 10-15
percent protein) and do little or no exercise starting three days before your
event.
Muscles loaded with unused glycogen will be available to work for
longer periods of time during competition. See your doctor for advice before
trying a carb-loading diet.

orthoinfo.aaos.org