Fast-twitch muscle fibers are mainly used when the body needs to make sudden, more powerful movements. They are suited for short, fast bursts of activity that don't require as much oxygen. The more you work your fast-twitch muscle fibers, the stronger they'll be.
Some exercises that can help build fast-twitch muscle fibers include:
• Box squats
• Repeat hurdle jumps
• Single leg squats
• Six triples or six doubles
Slow-twitch muscle fibers, also known as red fibers, are characterized by a slow contraction speed and high endurance capacity. They have a higher oxidative capacity than fast-twitch muscle fibers, which have higher glycolytic enzyme activity.
Here are some other characteristics of slow-twitch muscle fibers:
• Fatigue resistance
Slow-twitch fibers are relatively fatigue resistant because they have a high myoglobin content.
• Blood-carrying myoglobin
Slow-twitch fibers contain more blood-carrying myoglobin, which creates a darker appearance.
• Mitochondria and blood vessels
Slow-twitch fibers contain more mitochondria and blood vessels, allowing them to use oxygen efficiently for energy production.
• Sustain force
Slow-twitch fibers can sustain force for an extended period of time, but they are not able to generate a significant amount of force.
Slow-twitch muscles are well suited for endurance exercise. Activities that can strengthen your slow-twitch muscles include: Running, Jogging, Hiking, Rowing, Swimming.
You can also strengthen your slow-twitch muscles with weight training. When weight training, you can try:
• Higher numbers of reps
• Shorter rest periods
• Slower motions
• Lengthening the amount of time spent under tension
