type II muscle cell type IIx muscle cell 2024-11-04T10:26:29Z type 2x muscle fiber type 2x muscle cell type IIx muscle fiber In humans, type IIx fiber contains high levels of MYLK2, enhancing contraction speed and force via myosin phosphorylation, especially under low calcium. This mechanism supports post-activation potentiation, increasing force output in fast-twitch muscles. Additionally, this fiber has abundant ACTN3 (α-actinin-3), linked to muscle power, and exhibits the highest shortening velocity among human muscle fiber types. Notably, type IIx fiber is selectively lost in aging-related sarcopenia, increases in proportion in type 2 diabetes and obesity, and is the first to degenerate in Duchenne Muscular Dystrophy, impacting muscle function across various conditions. A fast type II muscle cell that is part of the skeletal muscle tissue. This cell is characterized by its intermediate metabolic profile, utilizing both glycolytic and oxidative pathways for energy production. In humans, it is distinguished by the expression of myosin heavy chain 1 (MYH1). type 2x fiber