GLOSSARY

Exercise-Induced Protein Catabolism describes exercise-associated breakdown of proteins into smaller constituents. Breakdown, amino-acid oxidation and net tissue balance are related but distinct processes.

Amino acids can contribute to energy metabolism during exercise, with contribution influenced by duration, energy and carbohydrate availability and training context. Oxidation of an amino acid is not identical to the rate of net muscle loss. Carbohydrate provision can reduce some amino-acid use under relevant conditions, while protein has important roles in repair and adaptation. BCAA or leucine oxidation is a specific process and does not establish that isolated amino-acid supplements are a superior exercise fuel.

Dietary protein provides amino acids for tissue maintenance and adaptation. Total daily intake, distribution across eating opportunities, protein quality and sufficient energy all matter. A precisely timed drink cannot compensate for an inadequate overall diet, while a convenient food or supplement can help when normal meals are difficult. Resistance training provides the relevant stimulus for muscle development. Interpreting protein as an exercise fuel should not distract from supplying carbohydrate and fat appropriately or from its structural and functional roles.

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.

Muscle and liver glycogen have related but different roles. Muscle glycogen supplies the muscle in which it is stored, while liver glycogen helps support blood glucose. An overnight fast can reduce liver carbohydrate availability without producing the same depletion in every muscle. Starting concentration, recruited fibers and exercise demand affect use. An estimate of total stores does not directly describe the availability of every local glycogen pool during a specific movement.

Energy requirements depend on body size and composition, activity, life stage and physiological circumstances. A maintenance estimate is a starting point for a defined situation rather than a permanent personal calorie ceiling. Training load, recovery, appetite and changes in body mass help evaluate its usefulness. Growth, illness or a change in training schedule may require reassessment. Adequate energy also needs appropriate carbohydrate, protein, fat and micronutrient provision; matching a calorie total alone does not guarantee a balanced sports diet.

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.