GLOSSARY

Pre-Exercise Glycogen Availability describes the glycogen present at exercise onset. Muscle and liver stores have different functions and need separate interpretation.

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.

Glycogen use depends on exercise intensity, duration, recruited muscles, training status and starting availability. A decline in one sampled muscle or fiber population should not be assumed to represent all stores throughout the body. Carbohydrate feeding can support blood glucose and performance during suitable exercise, but it does not guarantee uniform sparing of muscle glycogen. Depletion is a change in a finite pool, whereas depletion rate specifies the speed over an observation interval.

For example, an athlete can start a second session with lower glycogen after an earlier demanding workout. Food between sessions and the time available influence restoration. A scale increase after replenishment can include water, so the athlete should not interpret that short-term change automatically as fat gain or respond by withholding needed fuel.

Carbohydrate loading aims to increase glycogen stores before an event in which those stores may limit performance. Higher carbohydrate provision is usually combined with reduced training demands during preparation. Classical depletion-heavy protocols and more moderate approaches differ, and a severe depletion phase is not universally required. Extra glycogen is accompanied by water, so temporary body-mass gain is expected. A practiced, tolerated plan matters more than copying a protocol without considering event duration and the athlete's usual intake.