Recovery
Post-race recovery calculator.
From body mass before and after a long effort, the fluid to drink at 150% of the loss and the carbohydrate for a short recovery window at 1.2 g per kg per hour.
Inputs
Recovery
Enter both body masses.
How much should I drink after a marathon or long run?
The ISSN ultra-marathon stand reports that a low-sodium drink consumed at 150% of exercise-induced body mass loss gave better rehydration than the same drink at 100% of the loss, and that volumes above 200% are not recommended. It adds that plain water is unlikely to restore fluid balance after training, because of falling plasma sodium and the resulting urine output, and that greater volumes only helped when taken with more sodium. This tool takes your mass lost and shows 150% as the central figure, with 100% and 200% as the bounds. It treats 1 kg as 1 litre, a simplification.
For carbohydrate, the ISSN nutrient timing stand says that where rapid glycogen restoration is needed, with less than 4 hours of recovery, aggressive refeeding at 1.2 g per kg per hour is an option, and elsewhere describes high intake for four to six hours soon after exercise. It also says that when rapid recovery is not truly needed and daily carbohydrate matches energy demands, the timing of carbohydrate is much less important. Use the result only if your next hard session is soon.
Frequently asked questions
How much should I drink after a marathon?
The ISSN ultra-marathon stand reports 150% of the body mass lost works better than 100%, and does not recommend volumes above 200%. If you lost 1.5 kg, 150% is about 2.25 litres, spread over several hours, with sodium from food or drink.
How many carbs after a long run?
For recovery under 4 hours before your next session, the ISSN stand describes 1.2 g per kg per hour. For a 70 kg runner that is 84 g per hour. If you have a day or more, normal meals matching your energy needs are usually enough.
How do I measure body mass lost?
Weigh yourself before and after in the same way, as in the sweat rate method that the ACSM position stand describes. The difference is a rough fluid loss estimate.
Should I drink it all at once?
No. Spread it over the hours after exercise. Very large volumes of plain water in a short time risk hyponatraemia.
Sources
Checked
- Tiller et al., ISSN position stand: nutritional considerations for single-stage ultra-marathon training and racing, J Int Soc Sports Nutr 2019
- Kerksick et al., ISSN position stand: nutrient timing, J Int Soc Sports Nutr 2017
- Sawka et al., ACSM position stand: Exercise and fluid replacement, Med Sci Sports Exerc 2007
Ranges are quoted from the sources above and are general research or position-statement figures. Gel, powder and drink contents, spare gels and stop intervals are your own inputs; defaults are placeholders. One kilogram of body mass is treated as one litre of fluid.
Scope
Education only, not medical or dietetic advice. Needs differ by person, event, heat and training, and the published ranges are general. Try any fuelling or hydration plan in training, not for the first time on race day. If you have a medical condition (including diabetes, kidney or heart disease or high blood pressure), are pregnant or breastfeeding, or are under 18, ask your doctor or a registered dietitian first. Stop and get medical help for confusion, vomiting, severe headache, fainting or swelling of the hands and feet during or after a long effort.