In case your purpose is to PR a marathon, climb a mountain, or crush your coworkers within the annual workplace plank competitors, it’s essential to perceive sort 1 muscle fibers and how you can construct them.
Of the 2 main forms of skeletal muscle fibers, sort 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 how you can goal sort 1 fibers in your exercises, let’s first take a more in-depth take a look at what they’re and the way they operate.
What Are Kind 1 Muscle Fibers?
In comparison with sort 2 (fast-twitch) muscle fibers, that are bigger and extra highly effective, sort 1 muscle fibers have lengthy contraction instances (therefore their “slow-twitch” moniker). Because of this, they generate much less drive, 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.
How one can Prepare Kind 1 Muscle Fibers
Each muscle accommodates each sort 1 and sort 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 possibly can favor and construct one fiber sort over the opposite.
To develop your sort 1 muscle fibers, give attention to cardio and endurance-oriented actions and coaching modalities:
1. Regular-state coaching
Sustaining a gentle tempo for longer distances will hammer your sort 1 fibers (versus sprinting and interval coaching, which goal sort 2 fibers).
2. Resistance coaching
Weave lightweight, high-rep units into your routine to focus on your sort 1 fibers. Analysis additionally reveals that performing each lightweight/high-rep and heavy-weight/low-rep units may also help 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 groups — particularly your sort 1 fibers.
What Do Kind 1 Muscle Fibers Look Like?
Kind 1 muscle fibers require extra oxygen to provide vitality than sort 2 muscle fibers, so they’re pink. Their counterparts, sort 2 muscle fibers, that are extra anaerobic (oxygen-independent), are white.
“Kind 1 fibers are additionally a bit smaller,” Celiberti says. “Upon shut examination, sort 1 muscle fibers have increased capillary density and oxidative capability, in addition to a smaller diameter than sort 2 fibers.”
