What is the effect of strength training on muscle fibers?

Strength training has a pronounced effect on muscle fibers, significantly increasing both their size and strength. This process, known as hypertrophy, primarily occurs in fast-twitch fibers, which are responsible for generating maximum force and power during high-intensity activities. These fibers benefit greatly from the heavy loads and explosive movements typically involved in strength training.

However, strength training does not exclusively enhance fast-twitch fibers. It also positively influences slow-twitch fibers, which are important for endurance activities, albeit to a lesser extent. Slow-twitch fibers can experience some increases in size and strength with consistent strength training, particularly when the training incorporates moderate loads and higher repetitions.

Consequently, the correct understanding is that strength training impacts both fiber types, leading to an overall increase in muscle mass and functional capabilities, making option B the appropriate choice. This multifaceted stimulation of different muscle fiber types contributes to improved athletic performance and overall physical fitness.