7 min readPathway sheetOften a 5-mark answer; sometimes part of a 10-mark carbohydrate answer

Glycogen (carbohydrate) loading

Glycogen loading fills muscle glycogen well above normal before endurance events over 90 minutes. Today it simply means 10-12 g/kg a day for 36-48 hours with tapered training.

Who benefitsContinuous endurance events over about 90 minutes: marathon, road cycling, triathlon

Modern method (ACSM/AND/DC 2016)10-12 g/kg/day for 36-48 hours, with a training taper

EffectMuscle glycogen can roughly double; race pace is held for longer

Side effectWeight gain of about 1-2 kg: each gram of glycogen is stored with about 3 g of water

Methods of glycogen loading

Method	Plan	Merits and drawbacks
Classic (Scandinavian, 1960s)	Exhausting exercise, then about 3 days of very low carbohydrate with training, then about 3 days of very high carbohydrate with rest	Very high stores, but tiredness, irritability, low blood sugar and poor training in the low phase; rarely used now
Modified (Sherman, 1981)	Training tapers over 6 days; moderate carbohydrate (about 50% of energy) for 3 days, then high (about 70%) for 3 days	Similar stores without the depletion phase; easier to follow
Modern short method	10-12 g/kg/day for 36-48 hours with reduced training (ACSM/AND/DC 2016)	Simple, fits the taper week; the method used today

How to plan carbohydrate loading (modern method)

1
Check the event: continuous and longer than about 90 minutes? (Marathon yes; 400 m, kabaddi or a T20 innings no.)
2
Taper training in the final week so glycogen is not burned as fast as it is stored.
3★
For the last 36-48 hours, eat 10-12 g/kg/day of carbohydrate.
4
Choose low-fibre, low-fat carbohydrate: white rice, idli, dosa, chapati, potato, white bread, banana, jam, sweet lassi, fruit juice, rice flakes.
5
Spread it over 6-8 meals and snacks; cut back on fried foods, dals and salads to keep the volume manageable.
6
Drink well and expect 1-2 kg of weight gain from water stored with glycogen.
7
Practise the plan before a training long run, never for the first time before a race.
8
On race morning, eat a normal pre-event meal of 1-4 g/kg, 1-4 hours before the start.

★ one-way, controls the pace

Loading for a marathon runner

Problem

Arun weighs 60 kg and is running a marathon. Find his daily carbohydrate for loading, the energy it gives at 10 g/kg, and the amount per eating occasion if he eats 6 times a day.

Working

Range = 10-12 g/kg × 60 kg = 600-720 g a day.
At 10 g/kg: 600 g × 4 kcal = 2400 kcal from carbohydrate.
Per eating occasion: 600 ÷ 6 = 100 g carbohydrate.
Check: 12 × 60 = 720; 600 × 4 = 2400; 6 × 100 = 600.

Answer

600-720 g carbohydrate a day for 36-48 hours; at 10 g/kg this is 2400 kcal, about 100 g at each of 6 meals or snacks (exact values, no rounding).

Benefits vs drawbacks

BenefitsDelays glycogen depletion ('hitting the wall'), helps hold race pace in the last part of events over 90 minutes, and supports better decision-making late in long events.

DrawbacksHeavy, stiff feeling and 1-2 kg weight gain (a handicap for jumpers and weight-class athletes); stomach upset if fibre is high; no benefit for short events; people with diabetes need medical advice.

For the athlete

For a marathoner the dietitian swaps high-fibre grains and dals for low-fibre carbohydrate foods (white rice, idli, potato, banana, jam, sweet lassi) for the last 36-48 hours, so 600 g or more fits without bloating. Loading is not needed for kabaddi, sprints or cricket, where a normal high-carbohydrate diet is enough.

Exam angle

2 marks: “What is carbohydrate loading?” A diet-and-training plan that raises muscle glycogen above normal before endurance events over about 90 minutes; now 10-12 g/kg/day for 36-48 hours with a taper.

5 marks: “Explain the methods of glycogen loading and their importance.” Classic, modified (Sherman) and modern methods with their plans, merits and drawbacks; who benefits; low-fibre Indian food choices.

Remember it

Load for the long: over 90 min, 10-12 g/kg, 36-48 h.