Possible Clues:

• __-loading (pre-marathon preparation)
• "Hydrate" lead-in
• __-loading
• __-loading (racer's ritual)
• Runners' term
• ___-load (prepare for a marathon)
• ___-loading (pre-marathon prep)
• ___-loading (marathoner's routine)
• __ loading (racer's ritual)
• Starch, to a trainer