In case your objective is to PR a marathon, climb a mountain, or crush your coworkers within the annual workplace plank competitors, you might want to perceive kind 1 muscle fibers and construct them.

Of the 2 main forms of skeletal muscle fibers, kind 1 muscle fibers (a.ok.a. “slow-twitch” muscle fibers) are extra endurance-oriented and are essential to steady-state train, high-rep strength-training units, and isometric holds.

However earlier than we get into the specifics of goal kind 1 fibers in your exercises, let’s first take a more in-depth have a look at what they’re and the way they operate.

What Are Kind 1 Muscle Fibers?

In comparison with kind 2 (fast-twitch) muscle fibers, that are bigger and extra highly effective, kind 1 muscle fibers have lengthy contraction occasions (therefore their “slow-twitch” moniker). Consequently, they generate much less pressure, however they’re extra fatigue-resistant.

That’s why they’re your physique’s go-to fibers for longer-duration, steady-state actions like operating and biking, and for continuous-effort, higher-rep energy exercises like circuit coaching.

The right way to Prepare Kind 1 Muscle Fibers

Each muscle accommodates each kind 1 and kind 2 muscle fibers, and everyone seems to be born with their very own distinctive ratio of them, says Breanne Celiberti, MS, former adjunct teacher within the Human Efficiency division on the College of Tampa. However with focused coaching, you’ll be able to favor and construct one fiber kind over the opposite.

To develop your kind 1 muscle fibers, deal with cardio and endurance-oriented actions and coaching modalities:

1. Regular-state coaching

Sustaining a gradual tempo for longer distances will hammer your kind 1 fibers (versus sprinting and interval coaching, which goal kind 2 fibers).

2. Resistance coaching

Weave lightweight, high-rep units into your routine to focus on your kind 1 fibers. Analysis additionally exhibits that performing each lightweight/high-rep and heavy-weight/low-rep units can assist maximize hypertrophy (muscle constructing) by working each of the first muscle fiber sorts.

3. Circuit coaching

Again-to-back units of plyometric, body weight, and weightlifting workout routines will tax each your cardiorespiratory system and your muscle tissues — particularly your kind 1 fibers.

What Do Kind 1 Muscle Fibers Look Like?

Kind 1 muscle fibers require extra oxygen to supply vitality than kind 2 muscle fibers, so they’re purple. Their counterparts, kind 2 muscle fibers, that are extra anaerobic (oxygen-independent), are white.

“Kind 1 fibers are additionally a bit smaller,” Celiberti says. “Upon shut examination, kind 1 muscle fibers have greater capillary density and oxidative capability, in addition to a smaller diameter than kind 2 fibers.”