Fluid guidelines before, during and after exercise
Start hydrated (5-10 mL/kg 2-4 hours before), drink to keep losses under 2% during, and replace 1.25-1.5 L for every kg lost afterwards, with sodium.
An individual hydration routine
Fluid guidelines
| Phase | Guideline | Source | Practical tips |
|---|---|---|---|
| Before | 5-10 mL/kg 2-4 hours before | ACSM/AND/DC 2016 | Older ACSM (2007) advice: 5-7 mL/kg at least 4 h before, plus 3-5 mL/kg about 2 h before if urine is dark or scanty. A salty snack helps hold fluid. |
| During | Individual plan to prevent loss over 2% of body weight without gaining weight; 0.4-0.8 L/h is a common start | ACSM 2007; ACSM/AND/DC 2016 | Cool, flavoured drinks are taken more readily; for sessions over an hour or in heat, a sports drink with carbohydrate and sodium; use drinks breaks in cricket, quarter-breaks in hockey, half-time in football and kabaddi |
| After | 1.25-1.5 L per kg lost, with sodium, over the next few hours | ACSM/AND/DC 2016 | Drink more than was lost because some passes as urine; salty foods or drinks help retain it |
Sweat loss and fluid replacement for a cricketer
Rahul, a fast bowler, weighs 72.0 kg before a 3-hour session in Chennai and 70.6 kg after. He drank 1.5 L and passed no urine. Find his sweat loss, sweat rate, % body weight lost and the fluid he should drink afterwards.
- Weight lost = 72.0 − 70.6 = 1.4 kg, which equals about 1.4 L of fluid.
- Sweat loss = weight lost + fluid drunk − urine = 1.4 + 1.5 − 0 = 2.9 L.
- Sweat rate = 2.9 ÷ 3 = 0.97 L per hour, about 1 L per hour.
- % body weight lost = 1.4 ÷ 72.0 × 100 = 1.94%, just under 2%.
- Fluid to drink after = 1.4 × 1.25 to 1.4 × 1.5 = 1.75-2.1 L, with sodium.
- Check: 72.0 × 0.0194 = 1.40 kg; 1.25 × 1.4 = 1.75; 1.5 × 1.4 = 2.1.
Sweat loss 2.9 L (about 1 L/h); he lost 1.9% of body weight (just under the 2% limit); he should drink 1.75-2.1 L over the next few hours with salty food or a drink containing sodium. Next time he should drink more during play, as he replaced only about half his sweat. (Sweat rate rounded to two decimals; percentage to one decimal.)
Choosing fluids
| Situation | Good choices |
|---|---|
| Under an hour, cool conditions | Plain water |
| Over an hour, hot or humid, or a heavy salty sweater | Sports drink with about 6-8% carbohydrate and sodium; homemade salted nimbu pani with sugar |
| Recovery | Buttermilk with salt, milk, ORS, salted rice kanji; tender coconut water (rich in potassium but low in sodium, so add a salty snack) |
| Avoid | Alcohol (increases urine loss); fizzy drinks during play (bloating); trying a new drink on match day |
Signs of good hydration and practical tips
- Pale straw-coloured urine; dark urine means drink more.
- Morning body weight steady from day to day.
- Drink small amounts often; practise the plan in training.
- Weigh before and after sessions in heat to learn your own sweat rate.
- Never drink so much that you gain weight during exercise.
- Children and older adults feel thirst less, so remind them to drink.
On a hot match day, a sports dietitian weighs the cricket squad before and after play, works out each player's sweat rate and sets a personal drinks-break target. Players who lose a lot of salt (white streaks on the shirt) get salted nimbu pani or a sports drink rather than plain water.
2 marks: “How is sweat loss calculated?” Sweat loss = pre-exercise weight − post-exercise weight + fluid drunk − urine passed, taking 1 kg of weight as about 1 L.
5 marks: “Explain fluid guidelines before, during and after exercise.” Before: 5-10 mL/kg 2-4 h; during: keep loss under 2%, about 0.4-0.8 L/h; after: 1.25-1.5 L per kg lost with sodium; sources and tips.
10 marks: “Discuss fluid guidelines for athletes before, during and after exercise, with an example.” Routine diagram, guideline table with sources, a worked sweat-loss example, choice of fluids and signs of good hydration.
5-10 before, under 2% during, 1.25-1.5 after: mL/kg before, % weight during, litres per kg lost after.