What type 1 muscle fibers do and how to train them

If your goal is to run a PR marathon, climb a mountain, or crush your co-workers in the annual office plank competition, you need to understand type 1 muscle fibers and how to build them.

Of the two primary types skeletal muscle fiberstype 1 muscle fibers (or “slow” muscle fibers) are more focused on endurance and are essential for steady state exercisehigh rep strength training sets a isometric hold.

But before we get into the specifics of how to target type 1 fibers in your training, 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 fibers.which are larger and more powerful, type 1 muscle fibers have a long contraction time (hence their “slow twitch” nickname). As a result, they generate less force but are more resistant to fatigue.

This is why your body’s fibers are in a steady state for longer duration activities like run and cyclingand for sustained effort, higher-rep strength training such as 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 their own unique ratio, says Breanne Celiberti, MS, former adjunct instructor in the Department of Human Performance at the University of Tampa. But with targeted training, you can prioritize and build one type of fiber over another.

To develop your type 1 muscle fibers, focus on aerobic and endurance-oriented activities and training modalities:

1. Steady state training

Keeping a steady pace over longer distances it will hammer your type 1 fibers (unlike to sprint and interval trainingwhich target type 2 fibers).

2. Resistance training

Include light, high-rep sets in your routine and target type 1 fibers. Research also shows that performing low-weight/high-rep sets and high-weight/low-rep sets can help maximize hypertrophy (building muscle) by acting on both primary types of muscle fibers.

3. Circuit training

Back to back systems plyometric, body weightand weight training will be as taxing as yours 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, which is why they are red. Their counterparts, type 2 muscle fibers, of which there are more anaerobic (oxygen independent), are white.

“Type 1 fibers are also slightly smaller,” says Celiberti. “Upon close examination, type 1 muscle fibers have a higher capillary density and oxidative capacity, as well as a smaller diameter, than type 2 fibers.”