Carbohydrate Loading

Carbohydrate (glycogen) loading temporarily supersaturates muscle glycogen above normal to delay fatigue in prolonged endurance events — it benefits continuous efforts longer than about 90 minutes (marathons, long-distance triathlons, century rides), not short events.

The modern protocol is simpler than the classic 1960s depletion-then-load regimen: in the 1–3 days before the event, while tapering training (see cardio-progression), eat a high carbohydrate intake of about 10–12 g/kg of body weight per day (some protocols use ~8–12 g/kg). One- to two-day loads achieve near-maximal stores without the discomfort and risk of the old week-long depletion phase. Choose mostly easily digested, lower-fiber carbohydrate sources to limit GI bulk.

Expect water-weight gain: because each gram of glycogen stores ~3 g of water (see glycogen), successful loading adds a couple of pounds of glycogen-bound water — normal and not fat. On event day, continue with a familiar pre-event carbohydrate meal and in-race fueling (see endurance-fueling). Loading is unnecessary — and just adds weight — for short or moderate sessions; reserve it for genuinely long efforts.

• Benefits continuous endurance events >~90 min; useless for short events.
• Modern protocol: ~10–12 g/kg/day carbohydrate for 1–3 days while tapering.
• One- to two-day loads suffice; no week-long depletion needed.
• Expect ~2 lb water-weight gain (3 g water per g glycogen) — not fat.
• Continue pre-event meal and in-race fueling on the day.

• glycogen — the store being maximized; explains water gain.
• endurance-fueling — event-day and in-race fueling.
• carbohydrate-timing — broader carbohydrate timing.
• cardio-progression — training reduction that accompanies loading.