We’ve all heard the terms “fast-twitch” and “slow-twitch” when referring to muscle types. From ultra-marathoners to Olympic sprinters and everyone in between, bodies are all made up of two main types of muscle fibers: slow-twitch (known as Type 1) and fast-twitch (known as Type 2). While everyone is born with a finite number of slow and fast-twitch muscle fibers, knowing how to train both properly is important to maximize your endurance, speed and strength.
So what exactly are slow-twitch muscles and how are they different from their fast-twitch counterparts?
Slow-twitch muscles are more efficient at using oxygen to generate more fuel for continuous, extended muscle contractions over a long period. Slow-twitch muscle fibers rely on a rich supply of oxygenated blood. Within these muscles, there are a high density of capillaries, which help bring blood to the muscles. They generate less power and strength than fast-twitch fibers but are slower to fatigue meaning they can sustain activity for much longer. This type of muscle fiber is what you use primarily during endurance activities. Whether you’re a recreational distance runner or aspiring to train for a marathon or Ironman (or even one of these ultras only a maniac would attempt), work on training you’re slow-twitch muscles.
Training slow-twitch muscles
- When you’re lifting, focus on a higher number of reps (eight or more)
- Focus on a slower tempo
- Use shorter rest periods (30 seconds and under)
- With resistance training, increase your time under tension
- Every 2 weeks, train to failure of max reps and try and beat that each time
- Build up your endurance activities to make slow-twitch muscle fibers more efficient and fatigue resistant
- Incorporate long interval training
Even though genetic makeup accounts for slow and fast-twitch muscle fiber ratios, everyone can train both muscle fiber types to maximize their efficiency and improve performance. If you’re an endurance athlete, it doesn’t mean you can neglect training your fast-twitch muscles or visa-versa.