In case your objective is to PR a marathon, climb a mountain, or crush your coworkers within the annual workplace plank competitors, you want to perceive kind 1 muscle fibers and the way to construct them.
Of the 2 main forms of skeletal muscle fibers, kind 1 muscle fibers (a.okay.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 the way to goal kind 1 fibers in your exercises, let’s first take a better take a look at what they’re and the way they perform.
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 instances (therefore their “slow-twitch” moniker). Because of this, 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 power exercises like circuit coaching.
Easy methods 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 may 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 gentle 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 reveals 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 tissue — 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 larger capillary density and oxidative capability, in addition to a smaller diameter than kind 2 fibers.”
