GLOSSARY

Supplement Review reviews supplement use and outcomes over time, including benefit, symptoms, adherence, cost and changing circumstances.

Apparent individual responses combine biological variation, measurement error, expectations and changes in training or diet. A person classified as a nonresponder after one noisy test may not have a stable absence of benefit. Use repeated, relevant observations under comparable conditions and consider starting nutrient status or habitual intake. Genetic mechanisms can be informative without making a commercial genetic test a validated prescription. Individualization should improve a practical decision, not turn uncertain differences into permanent athlete labels.

A credible supplement claim needs relevant controlled evidence, an appropriate comparison and a meaningful outcome. Randomization, placebo control and blinding reduce different sources of bias but do not guarantee a useful result. Sample size, uncertainty, training status, sex, diet and protocol affect interpretation. A pooled estimate is not a promise to every individual. Mechanistic plausibility, a changed biomarker, exercise capacity and actual competition performance are distinct levels of information that should not be treated as interchangeable.

Absorption, distribution, metabolism and elimination determine how an ingredient reaches circulation and tissues. Plasma concentration does not directly establish muscle uptake or a useful performance effect. Half-life describes a concentration decline under defined conditions, while time to peak describes when a measured maximum occurs. Food, formulation, repeated use and individual physiology affect these processes. A faster or larger blood peak is therefore not automatically evidence that a formulation is better for the athlete's intended task.

For example, repeat a relevant performance observation under comparable training, diet and sleep conditions before labeling an athlete a nonresponder. A small difference can fall within measurement noise. Individualization is most useful when it changes a practical decision supported by repeated information rather than assigning a permanent category from one session.

A supplement can address a defined nutrient shortfall, provide a convenient sports-food format or target a specific performance mechanism. These purposes require different evidence and assessment. A product is not necessary simply because it is marketed to athletes, and normal training fatigue does not identify a nutrient deficiency. Begin with the athlete's diet, health, training and practical constraints, then define the expected benefit, suitable outcome and stopping or review point before adding a product.

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.

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.