GLOSSARY

Nutrition for Performance uses nutritional practices to support meaningful sporting outcomes. Performance benefit must be distinguished from changes in biomarkers or fuel oxidation alone.

A nutritional strategy should be evaluated by the quality and relevance of evidence, the athlete's response and the feasibility of implementation. Molecular signaling, a substrate-oxidation change, a laboratory capacity test and race performance are different outcomes. Association does not establish cause, and a response in one small study need not generalize to all athletes. Define the intended benefit before changing the plan, then evaluate training quality, recovery and performance under comparable circumstances rather than judging success by novelty.

Fatigue is a reduced ability or willingness to sustain the required task and has interacting central and peripheral contributors. Low carbohydrate availability can matter, but heat, hydration, pacing, sleep, muscle damage and illness can also contribute. A late-race slowdown does not prove that all glycogen is exhausted or that blood glucose is low. Persistent or unusual symptoms require appropriate assessment. A useful fueling review investigates plausible causes instead of assigning every performance decline to one missing nutrient.

Carbohydrate requirements vary with the intensity, duration and importance of the work. Daily intake relative to body mass describes a different quantity from an intake rate during exercise, which is commonly expressed per hour. A larger daily target does not mean the same amount should be consumed in every session. Match supply to the schedule, starting stores and practical tolerance, and distinguish grams eaten from grams absorbed or oxidized when discussing a fueling plan.

Energy availability describes dietary energy remaining after exercise expenditure, expressed relative to fat-free mass over a defined period. It differs from whole-day energy balance and from body-fat percentage. Calculations are sensitive to errors in food records, exercise expenditure and body-composition estimates. No single threshold or short observation establishes a diagnosis for every athlete. Persistent fatigue, impaired recovery or other concerning changes warrant assessment in the broader health and training context rather than a conclusion from one calculated value.

External training load describes the work performed, such as distance, power or repetitions. Internal load describes the athlete's response, such as heart rate or perceived exertion. Volume, intensity and duration contribute differently, so one summary number does not reveal all nutritional demands. Two sessions with similar duration can differ greatly in carbohydrate use and recovery needs. Food planning should reflect the actual work and subsequent schedule, while persistent mismatch between intake and load deserves review.

Recovery nutrition considers carbohydrate restoration, protein provision and fluid and electrolyte replacement according to what was depleted and when the athlete must perform again. A short turnaround raises the practical importance of early, tolerated intake. An ordinary meal may cover needs when there is more time, while portable options help when appetite or logistics interfere. Feeling less sore is not the same as demonstrating restored function, and nutrition cannot fully replace adequate rest or an appropriate training load.