Muscle Fiber Composition
The ACTN3 genotype role in fast-twitch vs slow-twitch muscle fiber efficiency and athletic training response.
Biological Mechanism & Scientific Context
The alpha-actinin-3 protein is exclusively expressed in type II (fast-twitch) glycolytic fibers responsible for explosive force generation. The common R577X null polymorphism results in complete absence of actinin-3, shifting metabolic efficiency toward oxidative endurance.
Interactive Tool Available
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