Effects of alcohol on the contractile function of slow and fast muscles: a review

Abstract

Skeletal muscle primarily consists of two types of muscle fibers: slow-twitch fibers and fast-twitch fibers. Slow-twitch fibers possess high oxidative capacity and resistance to fatigue, whereas fast-twitch fibers are associated with high-intensity, short-duration exercises. Studies have revealed that alcohol exerts negative effects on both types of muscle fibers. In rat experiments, alcohol exposure resulted in alterations in creatine kinase (CK) activity in both fast-twitch and slow-twitch muscles. Low concentration alcohol exposure increased CK activity in fast-twitch muscles but decreased CK activity in slow-twitch muscles. However, high concentration alcohol reduced CK activity in both muscle types. Furthermore, alcohol exposure was found to induce changes in muscle fiber types. Additionally, alcohol exposure affected the oxidative capacity of muscles. Low concentration alcohol exposure enhanced muscle oxidative capacity, while high concentration alcohol exposure decreased oxidative capacity in fast-twitch muscles.

Overall, this study indicates that alcohol intake has detrimental effects on skeletal muscle fibers and functionality. Alcohol leads to muscle fiber type transitions, decreased CK activity, and impaired oxidative capacity. These findings suggest the adverse impact of alcohol on muscle health, particularly its pronounced effects on fast-twitch fibers. These discoveries contribute to a deeper understanding of the mechanisms through which alcohol affects muscle and emphasize its detrimental effects on overall physical well-being.