Which type of exercise primarily targets Type I muscle fibers?

Type I muscle fibers, also known as slow-twitch fibers, are specialized for endurance and prolonged activities. They are characterized by their ability to sustain activity over extended periods without fatigue, making them highly efficient for aerobic metabolism. This is in contrast to Type II muscle fibers, which are designed for short bursts of strength and power, typically involved in activities requiring quick, explosive movements.

Endurance activities, such as long-distance running, predominantly rely on these Type I fibers because they require sustained aerobic energy production. During such activities, oxygen is utilized efficiently, allowing for a longer duration of exercise without significant fatigue. This aligns well with the physiological characteristics of Type I fibers, which excel at oxidative energy production due to their rich mitochondrial content and high levels of myoglobin.

In comparison, weight lifting and plyometric exercises primarily engage Type II fibers as they focus on short-duration, high-intensity efforts, while high-intensity interval training, although it can involve a combination of fiber types, is also typically more reliant on anaerobic pathways. Therefore, endurance activities like long-distance running are most directly linked to the recruitment and utilization of Type I muscle fibers, making this the correct choice.