Protein for exercise: roles and requirements before, during and after
Athletes need 1.2-2.0 g protein/kg/day (ACSM/AND/DC 2016), well above the ICMR-NIN adult RDA of 0.83 g/kg. Spread it as about 0.3 g/kg every 3-5 hours, especially after training.
Roles of protein in exercise
- Building and repair: training breaks down muscle protein; protein after exercise drives muscle protein synthesis and growth (hypertrophy).
- Enzymes: endurance training adds mitochondrial and fat-burning enzymes, all made of protein.
- Oxygen transport: haemoglobin and myoglobin are proteins.
- Hormones and immunity: protein hormones and antibodies; hard training raises the need for immune support.
- Connective tissue: collagen in tendons, ligaments and bone.
- Minor fuel: branched-chain amino acids are burned in muscle and alanine is turned into glucose in the liver, more so when glycogen is low.
- Fluid balance: plasma proteins hold water in the blood.
Protein requirements
| Group | g/kg/day | Source |
|---|---|---|
| Healthy Indian adult | 0.83 | ICMR-NIN 2020 RDA (older books: 1.0, the 2010 value) |
| Athletes in general | 1.2-2.0 | ACSM/AND/DC joint position, 2016 |
| Most exercising people | 1.4-2.0 | ISSN position stand, 2017 |
| Endurance athletes | 1.2-1.4 | Older ADA/DC/ACSM joint position, 2009; the 2016 update uses one range, 1.2-2.0, for all athletes |
| Strength-trained athletes | About 1.2-1.7 | Older ADA/DC/ACSM joint position, 2009 |
| Lean strength athletes cutting body fat | Higher, about 2.3-3.1 | ISSN 2017, to keep muscle during an energy deficit |
Protein before, during and after exercise
| Timing | Guideline | Indian food ideas |
|---|---|---|
| Before (1-4 hours) | A moderate amount in the pre-exercise meal; keep it easy to digest | Idli-sambar, curd with poha, egg on toast |
| During | Usually not needed; small amounts may help in ultra-endurance events | Not routinely |
| After (within about 2 hours) | About 0.3 g/kg (20-40 g) of high-quality, leucine-rich protein, with carbohydrate | Milk or banana milkshake, curd, paneer roll, eggs, chicken, sprouts with curd |
| Through the day | 0.3 g/kg every 3-5 hours over 4-5 meals | Dal, milk, curd, egg, fish, soya chunks |
| Before sleep | 30-40 g of slow (casein-rich) protein (ISSN) | A glass of milk, curd or paneer |
Daily protein for a kabaddi player
Vikram, a 75 kg kabaddi raider, does strength and skill training. Find (a) his protein at 1.6 g/kg/day, (b) the per-meal dose at 0.3 g/kg, (c) the ICMR-NIN 2020 RDA for comparison, (d) the share of energy from protein in a 3600 kcal diet.
- (a) 1.6 × 75 = 120 g protein a day.
- (b) 0.3 × 75 = 22.5 g per meal, about 20-25 g over 5 eating occasions (5 × 22.5 = 112.5 g), with the rest from snacks.
- (c) ICMR-NIN RDA: 0.83 × 75 = 62.25 g, about 62 g. His need is nearly double.
- (d) Energy from protein = 120 × 4 = 480 kcal; 480 ÷ 3600 = 0.133, about 13% of energy.
- Check: 120 ÷ 75 = 1.6; 62 ÷ 75 ≈ 0.83.
120 g protein a day (about 22.5 g a meal), compared with about 62 g for a non-athlete of the same weight; protein gives about 13% of a 3600 kcal diet (rounded to whole numbers).
Too little vs too much protein
Most Indian vegetarian athletes can reach 1.2-2.0 g/kg from milk, curd, paneer, dal, soya and sprouts if every meal has a protein food; cereal with pulse (idli, khichdi, rajma-rice) improves protein quality. A glass of milk with a banana after training gives protein and carbohydrate together.
2 marks: “State the protein requirement of athletes.” ACSM/AND/DC 2016: 1.2-2.0 g/kg/day, compared with the ICMR-NIN 2020 adult RDA of 0.83 g/kg/day.
5 marks: “Explain the role of protein in exercise.” Muscle repair and growth, enzymes, haemoglobin and myoglobin, hormones and immunity, connective tissue, minor fuel, fluid balance.
10 marks: “Discuss the role of protein for exercise and the requirements before, during and after exercise.” Roles, daily g/kg table with sources, timing table (before, during, after, through the day, before sleep), a worked example and risks of too much or too little.
Protein 1-2-3: 1.2-2.0 g/kg a day, 0.3 g/kg a meal.