GLOSSARY

Fat Oxidation Zone is an intensity range defined around a selected fat-oxidation criterion. State the definition because different protocols can produce different zones.

Maximal fat oxidation is the highest absolute fat-oxidation rate identified in a specified test. Fatmax is the exercise intensity associated with that rate, and a surrounding zone depends on its definition. Protocol, recent diet, nutritional state and measurement assumptions influence the result. The test does not identify a universal best intensity for losing body fat or improving every performance outcome. Training prescription should also consider conditioning goals, total work, recovery and the athlete's actual event.

Fat contributes to exercise energy through circulating fatty acids and intramuscular lipid stores. Greater fat availability, uptake or mobilization does not automatically mean a greater oxidation rate. Relative contribution and absolute rate are also different: the percentage can rise while total exercise demand changes. Oxidizing more fat during one session does not by itself establish greater long-term body-fat loss. Interpret the measured process, exercise intensity, diet and overall energy balance together.

Exercise uses a mixture of fuels whose proportions change with intensity, duration, training and diet. The crossover concept describes a shift toward greater carbohydrate contribution as intensity rises under specified conditions. It is a model of relative fuel use, not an on-off switch that turns fat metabolism off. The crossover point is not fixed across all individuals or protocols. Interpret substrate patterns with the actual workload and available fuel rather than a universal heart-rate zone.