If your goal is to run a marathon, climb a mountain, or crush your colleagues in the annual office plank competition, you need to understand type 1 muscle fibers and how to build them.
Among the two main types of skeletal muscle fibersType 1 muscle fibers (called “slow twitch” muscle fibers) are more oriented toward endurance and are crucial for steady state exercisehigh-rep strength training sets and isometric shots.
But before we get into the details of how to target type 1 fibers in your workouts, let’s first take a closer look at what they are and how they work.
What are type 1 muscle fibers?
Compared to type 2 (fast-twitch) muscle fiberswhich are larger and more powerful, type 1 muscle fibers have long contraction times (hence their nickname “slow twitch”). As a result, they generate less force, but they are more resistant to fatigue.
This is why they are your body’s preferred fibers for long-lasting, stable activities like running And bikeand for continuous effort, higher repetition workouts, like circuit training.
How to train type 1 muscle fibers
Every muscle contains both type 1 and type 2 muscle fibers, and each is born with its own ratio, says Breanne Celiberti, MS, former assistant instructor in the department of human performance at the University of Tampa. But with targeted training, you can prioritize and develop one type of fiber over another.
To develop your type 1 muscle fibers, favor aerobic and endurance-oriented activities and training methods:
1. Steady state training
Maintain a brisk pace for longer distances, your type 1 fibers will be hammered (unlike sprinter And interval trainingwhich target type 2 fibers).
2. Resistance training
Incorporate light, high-rep sets into your routine to target your type 1 fibers. Research also shows that performing light/high-rep and heavy/low-rep sets can help maximize hypertrophy (muscle strengthening) by working the two main types of muscle fibers.
3. Circuit training
Back-to-back sets of plyometric, body weightand weightlifting exercises will test both your cardiorespiratory system and your muscles – especially your type 1 fibers.
What do type 1 muscle fibers look like?
Type 1 muscle fibers require more oxygen to produce energy than type 2 muscle fibers, so they are red. Their counterparts, type 2 muscle fibers, which are more anaerobic (independent of oxygen), are white.
“Type 1 fibers are also a bit smaller,” says Celiberti. “Upon close examination, type 1 muscle fibers have higher capillary density and oxidative capacity, as well as a smaller diameter than type 2 fibers.”
