If your goal is to run a marathon, climb a mountain, or beat 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 (also known as slow-twitch muscle fibers) are more endurance oriented and are key to steady-state exercisehigh rep strength training sets and isometric holds.
But before we get into the specifics of how to target type 1 fibers in your workouts, let’s take a closer look at what they are and how they work.
What are type 1 muscle fibers?
In comparison with type 2 (fast-twitch) muscle fiberswhich are larger and more powerful, type 1 muscle fibers have a long contraction time (hence their nickname “slow twitch”). As a result, they generate less force but are more resistant to fatigue.
That’s why they’re your body’s go-to fibers for longer-term, steady-state activities like jogging and cyclingand for strength exercises with continuous effort, high repetitions such as circuit training.
How to train type 1 muscle fibers
Every muscle contains type 1 and type 2 muscle fibers, and everyone is born with their own unique ratio of these, says Breanne Celiberti, MS, former assistant professor in the department of human performance at the University of Tampa. But with targeted training, you can favor and build one type of fiber over another.
To develop type 1 muscle fibers, focus on aerobic and endurance activities and training modalities:
1. Training in a steady state
Keeping an even pace for longer distances it will nail your type 1 fibers (as opposed to sprinting and interval trainingwhich target type 2 fibers).
2. Resistance training
Incorporate light, high-rep sets into your routine to target type 1 fibers. Research also shows that performing light/high-rep sets and heavy/low-rep sets can help maximize hypertrophy (building muscle) by working both primary types of muscle fibers.
3. Circuit training
Sets one after the other plyometric, body weightand weight lifting exercises will tax yours as well 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, of which there are more anaerobic (independent of oxygen), they are white.
“Type 1 fibers are also a little smaller,” says Celiberti. “After careful examination, type 1 muscle fibers have a higher capillary density and oxidative capacity, as well as a smaller diameter than type 2 fibers.”
