Sports Nutrition is the application of nutrition principles to the requirements of physical training, exercise performance, recovery and, where relevant, competition. It encompasses energy intake, carbohydrate, protein, fat, fluids, electrolytes, micronutrients, meal timing and the use of selected supplements. The appropriate nutritional strategy depends on the sport, training volume, intensity, duration, body composition goals, environmental conditions and individual tolerance. Sports nutrition is therefore not a single diet or universal food plan. A strategy appropriate for an endurance athlete undertaking prolonged training can differ substantially from one appropriate for a strength athlete or a person performing occasional recreational exercise.
Energy availability is a central concept because physical activity increases energy expenditure while the body also requires energy for basic physiological functions. Chronic mismatch between intake and expenditure can affect performance, recovery and physiological function. Carbohydrate is a major fuel for moderate-to-high intensity exercise because it can be metabolised rapidly and is stored primarily as muscle and liver glycogen. Fat contributes substantially to energy supply during lower-intensity and prolonged activity, while protein provides amino acids for tissue maintenance and adaptation but is not normally the preferred primary fuel for most exercise. The relative contribution of each fuel depends on exercise intensity, duration, nutritional status and training adaptation.
Carbohydrate requirements vary according to training load and the demands of the activity. Higher-volume endurance training generally creates greater glycogen demands than brief low-intensity exercise. Consuming carbohydrate before exercise can help support glycogen availability, while carbohydrate during prolonged exercise can provide an exogenous energy source and delay depletion of available carbohydrate stores. After demanding exercise, carbohydrate supports glycogen restoration, particularly when another substantial training session occurs relatively soon. The precise amount and timing should be adjusted to the duration and intensity of exercise rather than treating carbohydrate intake as a fixed requirement for every workout.
Protein is important for maintaining and adapting skeletal muscle and other tissues. Resistance exercise and other forms of training stimulate processes involved in muscle protein turnover, while dietary protein provides amino acids required for protein synthesis. Protein quality, total daily intake, distribution across meals and the timing relative to exercise can all be relevant. Essential amino acids, particularly leucine, play important roles in stimulating muscle protein synthesis. However, consuming increasingly large quantities of protein does not produce unlimited increases in adaptation. Adequate total energy, resistance training, sleep and overall dietary quality also influence outcomes.
Hydration affects thermoregulation, cardiovascular function and exercise performance, particularly during prolonged activity or hot conditions. Sweat contains water and electrolytes, with sodium generally representing the most abundant electrolyte lost in sweat, although sweat composition varies considerably between individuals. Drinking too little can contribute to dehydration and impaired performance, while excessive fluid intake can also be dangerous because it can contribute to exercise-associated hyponatraemia. Hydration strategies should therefore account for exercise duration, environmental conditions, individual sweat rate and access to fluids rather than relying on a universal volume recommendation.
Micronutrients such as iron, calcium, vitamin D, vitamin B12 and folate can be important in specific circumstances, but supplementation is not automatically beneficial when dietary intake is adequate. Athletes with restricted diets, high energy demands or particular physiological circumstances may have increased risk of deficiencies. Iron is particularly relevant to oxygen transport because it is required for haemoglobin and other proteins involved in oxygen metabolism. Calcium and vitamin D contribute to bone health, while numerous vitamins and minerals participate in energy metabolism and other physiological processes. Nutritional assessment is preferable to indiscriminate high-dose supplementation.
Sports supplements include products such as carbohydrate drinks, protein powders, caffeine, creatine, electrolyte products and other compounds marketed for performance or recovery. Evidence varies substantially between products, doses and circumstances. Creatine monohydrate, for example, has substantial evidence for improving performance in repeated high-intensity exercise and supporting gains from resistance training, while many commercially marketed supplements have weaker or inconsistent evidence. Supplement quality also matters because contamination or inaccurate labelling can create risks, particularly for athletes subject to anti-doping rules. Food-first approaches can provide most nutritional requirements, with supplements considered selectively where there is a clear rationale.
Sports nutrition is often confused with restrictive dieting or appearance-focused eating, but its primary technical purpose is to support training, health and performance. Effective nutrition requires matching energy and nutrient intake to workload while maintaining sufficient dietary variety and long-term sustainability. Timing can matter, particularly around prolonged or closely spaced training, but total daily intake usually provides the broader nutritional foundation. Individualisation is essential because gastrointestinal tolerance, food preferences, cultural dietary patterns, body size, training schedules and performance objectives differ. A sound sports-nutrition strategy therefore integrates food, fluids, recovery and training demands rather than relying on a single nutrient, supplement or rigid meal pattern.
