Sports nutrition

In short

Sports nutrition is the applied science of matching energy, macronutrient, micronutrient and fluid intake to the demands of training, competition and recovery. It decides whether an athlete can sustain intensity, repair tissue, keep immunity and bone health, and reach competition weight without losing performance. It is examined in B.P.Ed and B.Sc Sports Science papers (Sports Science / Exercise Physiology / Health and Nutrition), in NET Physical Education, and in entry tests for SAI, NIS Patiala diploma courses and university coaching posts. It is used daily by strength and conditioning coaches, sports dietitians at SAI centres and IPL/ISL franchises, physiotherapy and rehab teams, school PE departments and fitness-industry employers (Cult.fit, Anytime Fitness, Decathlon, HealthifyMe).

Explained

Energy systems and where fuel comes from

• ATP-PCr (phosphagen) system — immediate, 0-10 s all-out work (shot put, 100 m, a single lift); fuel is stored ATP and creatine phosphate; no oxygen, no lactate.
• Anaerobic glycolysis — 10 s to about 2 min (400 m, 50 m swim); glucose/glycogen → pyruvate → lactate; produces 2 ATP per glucose; H⁺ accumulation causes the burn and fatigue.
• Oxidative (aerobic) system — beyond ~2 min; carbohydrate and fat oxidised in mitochondria; ~30-32 ATP per glucose; fat gives more ATP per gram but needs more oxygen per ATP.
• Crossover concept: as intensity rises, the share of fat falls and carbohydrate rises; above roughly 70-75% VO₂max carbohydrate dominates, so glycogen depletion sets the limit in endurance events.
• Energy content (Atwater values): carbohydrate 4 kcal/g, protein 4 kcal/g, fat 9 kcal/g, alcohol 7 kcal/g; 1 kcal = 4.184 kJ.
• Stores in a 70 kg trained male (approximate): muscle glycogen ~400 g, liver glycogen ~100 g, blood glucose ~5 g, fat 10-15 kg. Glycogen is the small, decisive store — hence "hitting the wall" around 90-120 min of hard endurance work.

Macronutrients: function and athlete requirements

• Carbohydrate — the performance nutrient. Forms: monosaccharides (glucose, fructose), disaccharides (sucrose, lactose, maltose), polysaccharides (starch, glycogen, dietary fibre).
  • Intake guidance (ACSM/IOC consensus, widely taught): light training 3-5 g/kg/day; moderate ~1 h/day 5-7; endurance 1-3 h/day 6-10; extreme >4-5 h/day 8-12 g/kg/day.
  • Glycaemic index (GI): high-GI foods (white rice, potato, glucose, banana ripe, sports drink) for rapid refuelling after exercise; low-GI (dal, rajma, oats, whole wheat, most Indian pulses) for sustained pre-event energy and for athletes with diabetes.
• Protein — repair, enzyme and hormone synthesis, immune function; not a primary fuel (contributes 5-10% at most).
  • Endurance athletes 1.2-1.4 g/kg/day; strength/power 1.6-2.0 g/kg/day; up to 2.0-2.5 g/kg/day during energy restriction to protect lean mass. ICMR-NIN RDA 2020 for a sedentary adult is ~0.83-1.0 g/kg/day — athletes need more, which is the standard exam contrast.
  • Quality: judged by DIAAS/PDCAAS and leucine content. Complete proteins — egg, milk, paneer, fish, chicken, soy. Indian vegetarian practice uses complementation: cereal + pulse (roti-dal, idli-sambar, khichdi, rajma-chawal) to cover limiting amino acids (lysine in cereals, methionine in pulses).
  • Timing: 0.3 g/kg (≈20-25 g, ~2.5 g leucine) every 3-4 hours; a dose before sleep aids overnight muscle protein synthesis.
• Fat — 20-35% of energy, not below 20% (needed for fat-soluble vitamins A, D, E, K and hormone synthesis). Essential fatty acids: linoleic (omega-6) and alpha-linolenic (omega-3); Indian sources — mustard oil, flaxseed, walnut, fish. Limit trans fat; FSSAI caps industrial trans fat at 2% of total fat in oils and fats.
• Fibre — 25-40 g/day for health, but reduced in the 24 h pre-competition meal to avoid GI distress.

Micronutrients, hydration and electrolytes

• Iron — oxygen transport; deficiency is the commonest nutritional problem in Indian athletes, especially female and vegetarian. Haem iron (meat, liver) absorbs far better than non-haem (ragi, bajra, green leafy, jaggery); vitamin C (amla, lemon, guava) enhances absorption, while tea/coffee tannins, phytates and calcium taken with the meal inhibit it. ICMR-NIN RDA 2020: ~19 mg/day adult men, ~29 mg/day women (vegetarian Indian diets, 8% bioavailability) — screen ferritin before supplementing.
• Calcium and vitamin D — bone mineral density and stress-fracture prevention; RDA ~1,000 mg calcium/day for adults. Vitamin D deficiency is very common in Indian athletes despite sunshine (indoor training, skin cover, pollution).
• Others — sodium and potassium (fluid balance, nerve conduction), magnesium and zinc (lost in sweat), B vitamins (energy metabolism), antioxidants A, C, E (from food, not megadoses — high-dose antioxidant supplements may blunt training adaptation).
• Hydration: total body water ~60% of body mass. A 2% body-mass fluid deficit measurably reduces endurance and cognitive performance; >4-5% risks heat exhaustion/heat stroke, a real hazard in Indian summer training.
  • Pre-exercise: 5-10 ml/kg 2-4 h before. During: match sweat rate as far as tolerable, usually 400-800 ml/h; above 60-90 min add 30-60 g carbohydrate/h and sodium. After: 1.25-1.5 litres per kg of body mass lost, with sodium to retain it.
  • Sports drink types: hypotonic (<4 g/100 ml CHO — fast fluid), isotonic (4-8 g/100 ml, ~6% — the standard compromise), hypertonic (>8% — fuel, slower gastric emptying). ORS is a rehydration solution, not an exercise drink.
  • Hyponatraemia (water intoxication) — drinking plain water far beyond sweat loss in long events; headache, nausea, confusion, seizures. Prevented by sodium-containing drinks and by not over-drinking.
• Sweat is hypotonic to plasma: sodium ~20-80 mmol/L, potassium ~4-8 mmol/L; "salty sweaters" need extra sodium.

Nutrition around competition

1. Carbohydrate loading — classic Astrand/Bergström 6-7 day depletion-then-loading protocol is now replaced by the modified (Sherman) 3-day taper at 10-12 g CHO/kg/day with reduced training; useful only for continuous events over ~90 min. Each gram of stored glycogen binds ~3 g water, so expect 1-2 kg weight gain.
2. Pre-competition meal — 1-4 g CHO/kg, 3-4 h before; low fat, low fibre, moderate protein, familiar and well-tolerated foods (upma, poha, idli, curd rice, banana, toast with jam). Nothing new on competition day.
3. During — events >60 min: 30-60 g CHO/h; events >2.5-3 h: up to 90 g/h using a glucose:fructose mix (multiple transporters, SGLT1 and GLUT5) to beat the single-transporter ceiling; fluid and sodium as above.
4. Recovery — the 4 Rs: Refuel (1.0-1.2 g CHO/kg/h for the first 4 h when turnaround is short), Repair (20-25 g quality protein), Rehydrate (150% of fluid lost), Rest. The "glycogen window" matters mainly when the next session is within ~8 h.
5. Multiple events in a day / tournaments — small high-GI carbohydrate snacks and fluid between bouts; avoid high fat and high fibre.
6. Travel and heat — in Indian conditions plan safe water (sealed/boiled), food hygiene, pre-cooling and extra sodium; acclimatise 7-14 days.

Body composition, weight management and disordered eating

• Methods: skinfolds (Jackson-Pollock, Durnin-Womersley; ISAK-standardised sites), BIA (affected by hydration), hydrostatic weighing, DEXA (reference standard), air displacement plethysmography.
• BMI misclassifies muscular athletes — a 95 kg rugby forward can be "obese" by BMI with 10% fat. Indian public-health cut-offs are lower than WHO's: overweight ≥23, obese ≥25 kg/m².
• Weight-category sports (wrestling, boxing, weightlifting, judo) — gradual loss of 0.5-1.0 kg/week at a 500-750 kcal/day deficit with protein held high. Rapid "making weight" by sauna suits, laxatives, diuretics and starvation causes dehydration, loss of strength and, in documented cases, death; diuretics are also prohibited substances.
• Gain of lean mass — 300-500 kcal/day surplus with 1.6-2.0 g protein/kg and progressive resistance training; expect ~0.25-0.5 kg/week.
• RED-S (Relative Energy Deficiency in Sport) — low energy availability (<30 kcal/kg fat-free mass/day) impairs metabolic rate, menstrual function, bone health, immunity, mood and performance. The older female athlete triad (low energy availability, menstrual dysfunction, low bone mineral density) is the subset. Screen, refer, restore energy intake; do not treat with calcium alone.
• Disordered eating and anorexia athletica are commoner in aesthetic and weight-class sports; the response is referral, not coaching advice.

Ergogenic aids, supplements and Indian regulation

• Good evidence (IOC consensus): creatine monohydrate (loading 20 g/day in 4 doses for 5-7 days, or 3-5 g/day; gains in repeated high-intensity work and lean mass); caffeine 3-6 mg/kg about 60 min before (removed from the prohibited list in 2004, still monitored); beta-alanine (3-6 g/day, buffers via carnosine); sodium bicarbonate 0.2-0.3 g/kg for 1-7 min events; dietary nitrate/beetroot juice; sports drinks, gels and whey/casein as food replacements.
• Weak or no evidence: most "fat burners", BCAA beyond adequate protein, HMB in trained athletes, chromium picolinate, glutamine for performance, ketone esters (unsettled).
• Prohibited: anabolic androgenic steroids, hGH, EPO, SARMs, stimulants, diuretics and masking agents. India's regulator is NADA (National Anti-Doping Agency), functioning under the National Anti-Doping Act, 2022 with the National Board for Anti-Doping and the National Dope Testing Laboratory (NDTL); testing follows the WADA Code and the Prohibited List, which is revised each January. Indian athletes have a high adverse-finding record, largely from contaminated supplements.
• Strict liability — the athlete is responsible for whatever is in their body; a contaminated supplement is not a defence. Use batch-tested products (Informed Sport, NSF Certified for Sport) and check the current Prohibited List and any TUE (Therapeutic Use Exemption) need.
• Food law: supplements and sports foods are regulated by FSSAI under the Food Safety and Standards Act, 2006, with the Food Safety and Standards (Health Supplements, Nutraceuticals, Food for Special Dietary Use, Food for Special Medical Purpose, Functional Food and Novel Food) Regulations, 2016, which include a category for food for special dietary use for athletes/sportspersons; labelling and claims follow the Labelling and Display Regulations, 2020 (these regulations are amended frequently — verify the current amendment before quoting a limit). GST on most protein powders and nutraceutical supplements is 18%.
• Indian reference values come from ICMR-NIN: the RDA/EAR report (2020) and the Dietary Guidelines for Indians, 2024, with the "My Plate for the Day" model and the NIN food composition tables (IFCT 2017) used for diet planning.

Key points

• Energy systems - ATP-PCr (0-10 s), glycolytic (10 s-2 min), oxidative (>2 min); all three always run, the mix shifts with intensity.
• Energy values - CHO 4, protein 4, fat 9, alcohol 7 kcal/g; 1 kcal = 4.184 kJ.
• Carbohydrate - the limiting fuel; 3-12 g/kg/day by training load; glycogen ~500 g total in a trained adult.
• Protein - 1.2-1.4 g/kg endurance, 1.6-2.0 g/kg strength; 0.3 g/kg per meal, ~2.5 g leucine per dose.
• Fat - 20-35% of energy, never below ~20%; carries vitamins A, D, E, K.
• Protein complementation - cereal + pulse (roti-dal, idli-sambar) makes vegetarian Indian diets complete.
• Glycaemic index - high-GI after exercise for fast refuelling, low-GI before for steady release.
• Carbohydrate loading - only for continuous events >90 min; 3-day taper at 10-12 g/kg/day; +1-2 kg from bound water.
• Pre-event meal - 1-4 g CHO/kg, 3-4 h prior, low fat and fibre, nothing unfamiliar.
• During exercise - 30-60 g CHO/h beyond 60 min; up to 90 g/h with glucose:fructose beyond ~2.5 h.
• Recovery 4 Rs - Refuel 1.0-1.2 g/kg/h, Repair 20-25 g protein, Rehydrate 150% of loss, Rest.
• 2% dehydration - the performance threshold; rehydrate 1.25-1.5 L per kg lost, with sodium.
• Hyponatraemia - too much plain water in long events; sodium-containing fluids prevent it.
• Iron - ICMR-NIN RDA ~19 mg (men) and ~29 mg (women)/day; vitamin C aids, tea and phytate inhibit absorption.
• RED-S - low energy availability (<30 kcal/kg FFM/day) harming bone, hormones, immunity and performance; triad is its subset.
• Proven ergogenics - creatine, caffeine, beta-alanine, bicarbonate, nitrate; most fat burners are not.
• Strict liability - NADA under the National Anti-Doping Act, 2022; a contaminated supplement is no defence.
• Indian references - ICMR-NIN RDA 2020, Dietary Guidelines for Indians 2024, IFCT 2017, FSSAI 2016 nutraceutical regulations.

Formulas and examples

Example 1 — Energy need and carbohydrate target for a hockey player. Male, 22 years, 70 kg, 175 cm, two training sessions a day.

• Mifflin-St Jeor BMR = (10 × 70) + (6.25 × 175) − (5 × 22) + 5 = 700 + 1,093.75 − 110 + 5 = 1,688.75 ≈ 1,689 kcal/day.
• PAL 2.0 (heavy twice-daily training) → TDEE = 1,689 × 2.0 = 3,378 kcal/day.
• Carbohydrate at 7 g/kg = 490 g → 1,960 kcal (58% of intake).
• Protein at 1.7 g/kg = 119 g → 476 kcal (14%).
• Fat = 3,378 − 1,960 − 476 = 942 kcal → 942/9 = 104.7 g fat/day (28% of energy) — within the 20-35% band.

Example 2 — Sweat rate and rehydration in Chennai heat. Pre-training 68.4 kg; post-training 66.9 kg; drank 900 ml; no urine; session 90 min.

• Mass lost = 68.4 − 66.9 = 1.5 kg.
• Sweat loss = 1.5 + 0.9 = 2.4 L in 1.5 h → sweat rate 1.6 L/h.
• % body-mass loss = 1.5 × 100 / 68.4 = 2.19% — just past the 2% performance threshold.
• Replacement = 1.5 kg × 1.5 = 2.25 L over the next 4-6 h, with sodium (≈500-700 mg/L) and 1.0-1.2 g CHO/kg/h if training again the same day.
• Fluid plan next session: drink ~800 ml/h in planned breaks (full 1.6 L/h is rarely tolerable).

Example 3 — Carbohydrate loading for a marathon. Runner 60 kg, 3-day taper at 10 g/kg/day.

• Daily carbohydrate = 60 × 10 = 600 g/day = 2,400 kcal from carbohydrate alone.
• Practical day: 4 chapatis (≈80 g CHO) + 3 cups rice (≈135 g) + 2 bananas (≈54 g) + 500 ml sports drink at 6% (30 g) + 2 glasses fruit juice (≈60 g) + poha serving (≈50 g) + curd-rice, sweet potato and jaggery snacks to make up the rest.
• Expected mass gain = 1-2 kg from the ~3 g water bound per gram of extra glycogen — explain this to the athlete beforehand.
• During the race: 60 g CHO/h × 3 h = 180 g, i.e. about 3 litres of 6% drink or a gel (25 g) plus 500 ml drink per hour.

Example 4 — Energy availability in a gymnast (RED-S screen). Female, 50 kg, 18% body fat, intake 1,800 kcal/day, exercise energy expenditure 700 kcal/day.

• Fat mass = 50 × 0.18 = 9 kg → FFM = 50 − 9 = 41 kg.
• Energy availability = (1,800 − 700) / 41 = 1,100 / 41 = 26.8 kcal/kg FFM/day.
• Below the 30 kcal/kg FFM threshold → low energy availability; refer for RED-S assessment (menstrual history, bone density, ferritin) and raise intake by ~150-200 kcal/day to clear 30 (and further, towards 45 kcal/kg FFM, for full restoration).

Example 5 — Exercise energy cost by MET. 80 kg footballer, 60 min of competitive football (≈10 METs).

• Energy = 10 × 3.5 × 80 × 60 / 200 = (10 × 3.5 × 80 = 2,800; × 60 = 168,000; / 200) = 840 kcal.
• Replacing it with 6% sports drink alone would need 840/0.24 ≈ 3,500 ml per 60 min — not feasible, so solid recovery food is essential.

Where it is used

• National sports system: SAI National Centres of Excellence, NIS Patiala, Khelo India academies and TOPS employ sports dietitians who plan hostel menus, supplement protocols and anti-doping education.
• Professional franchises: IPL, ISL, PKL and Pro Volleyball teams run nutrition and hydration plans, body-composition monitoring (DEXA/skinfolds) and travel/match-day feeding.
• Fitness and wellness industry: Cult.fit, Anytime Fitness, Gold's Gym, Talwalkars, HealthifyMe and Fittr — trainer and nutrition-coach roles that require ACSM/NSCA/ISSN or NIS credentials.
• Food and supplement industry: MuscleBlaze, Optimum Nutrition India, Amul, Mother Dairy, Britannia and ITC sports-nutrition lines — product development, label claims and FSSAI compliance roles.
• Schools, colleges and defence recruitment: PE teachers planning diets for school teams, and candidates preparing for the Army/CAPF physical standards and weight norms.
• Clinical and rehab settings: sports medicine centres and hospital sports departments combine nutrition with injury rehabilitation (protein and vitamin D for fracture and tendon recovery).

Interview questions

• Q: Why is carbohydrate called the performance nutrient? A: It is the only fuel that can be burnt both aerobically and anaerobically and is the dominant fuel above ~70-75% VO₂max, yet stores are only about 500 g — so glycogen depletion, not fat supply, limits hard exercise.
• Q: How much protein does a strength athlete need, and does more help? A: 1.6-2.0 g/kg/day spread as 0.3 g/kg per meal; intakes beyond about 2.2 g/kg show no further gain in muscle protein synthesis and simply add energy.
• Q: What is carbohydrate loading and who should not do it? A: A 3-day taper with 10-12 g CHO/kg/day to supercompensate glycogen; pointless for events under about 90 min and unhelpful for weight-category or aesthetic athletes because of the 1-2 kg water gain.
• Q: How do you calculate an athlete's sweat rate? A: (pre-mass − post-mass + fluid drunk − urine) divided by the session duration in hours, with mass measured in minimal dry clothing before and after.
• Q: What is the 2% rule in hydration? A: A fluid deficit of 2% of body mass measurably reduces endurance, thermoregulation and cognitive performance, so fluid plans aim to keep losses under it.
• Q: What is exercise-associated hyponatraemia and how is it prevented? A: Dilution of blood sodium from drinking plain water well beyond sweat loss in long events, causing headache, nausea, confusion and in severe cases seizures; prevented by drinking to sweat rate with sodium-containing fluids.
• Q: How do you plan protein for a vegetarian Indian athlete? A: Combine cereals with pulses at each meal (roti-dal, idli-sambar, rajma-chawal), add milk, curd, paneer, soya and eggs if acceptable, and spread 20-25 g doses across four to five meals.
• Q: What is RED-S and how is it different from the female athlete triad? A: RED-S is the whole syndrome caused by low energy availability — affecting bone, endocrine, metabolic, immune, cardiovascular and psychological function in both sexes; the triad is the female subset of low energy availability, menstrual dysfunction and low bone density.
• Q: Which supplements have real evidence? A: Creatine monohydrate, caffeine, beta-alanine, sodium bicarbonate and dietary nitrate, plus sports drinks, gels and protein powders used as convenient food; most fat burners and exotic blends do not.
• Q: An athlete tests positive and blames a contaminated protein powder. What is the position? A: Strict liability applies under the WADA Code and India's National Anti-Doping Act, 2022 — the athlete is responsible for what is in their body; contamination may mitigate the sanction but is not a defence, which is why only batch-tested products should be used.
• Q: Why is BMI a poor tool for athletes? A: It cannot distinguish muscle from fat, so muscular athletes are misclassified as overweight or obese; skinfolds, DEXA or BIA should be used instead.
• Q: A boxer must lose 3 kg in two days before weigh-in. What do you advise? A: Advise against it — acute dehydration and starvation cut strength, endurance and cognition and carry real health risk; plan a graded 0.5-1.0 kg/week loss in the training cycle, or move up a weight class.

Common mistakes

• Treating protein as the fuel of sport and underestimating carbohydrate, then reporting fatigue as "lack of protein".
• Using fat's 9 kcal/g on carbohydrate or protein in diet calculations, or mixing kcal with kJ.
• Quoting the sedentary ICMR-NIN RDA for an athlete, or an athlete value for a general-population question — state which population the figure belongs to.
• Prescribing iron, calcium or vitamin D without blood work; excess iron is harmful and megadose antioxidants can blunt training adaptation.
• Giving ORS or a hypertonic drink during exercise, or recommending plain water for a four-hour event.
• Forgetting that creatine and carbohydrate loading add 1-2 kg of water — a problem in weight-class sports.
• Recommending any supplement without checking the current WADA Prohibited List and batch testing; assuming a shop label is proof of purity.

Related topics

Exercise physiology: energy systems and VO₂max · Sports training: principles, periodisation and load · Tests and measurement in physical education · Sports psychology · Sports physiotherapy · Anatomy and kinesiology