About Slow Twitch Muscle Fibers

What are slow twitch muscle fibers?

Simply put, slow twitch muscle fibers (also called Type 1 muscle fibers) are one of two types of muscle fibers. Slow twitch muscle fibers are the part of the muscles that convert fat into the energy that helps your body function. While they don’t contract as quickly as fast twitch muscle fibers, they also don’t produce lactic acid, which can cause fatigue and a number of other inhibitors to exercise.

How do they work?

Slow twitch muscle fibers are especially related to physical endurance, as they aren’t easily fatigued. They produce low intensity, consistent and repetitive contractions.

Athletes who focus on endurance rather than power tend to have a higher percentage of slow twitch muscle fibers. So, for example, a marathon runner would be more likely to regularly rely on his slow twitch muscle fibers than a sprinter.

According to personal trainer David Robson, successful athletics depends partially on the composition of muscle fibers in the body –and depending on the sport you’re participating in, one or the other is usually dominant in your body.

“The average person has about 50% slow and 50% fast fibers in most locomotory muscles. Those who dominate the athletic world, however, are blessed with muscle fiber composition variation compatible with their chosen sport,” says Robson.

What else should you know?

It’s important to remember that like all muscle tissue, you’ll see a reduction in slow twitch muscle fibers with age—but the good news is that if you maintain a regular exercise schedule which includes strength training, you can actually reduce or even reverse the risk.

And, while studies show that those between the ages of ten and twenty can most easily benefit from this type of training, older people will still benefit—it just takes a little longer.

Both slow and fast twitch muscle fibers are positively affected by strength training—but where fast twitch muscle fibers are likely to grow larger (especially in men), strengthening slow twitch muscle fibers will significantly increase your strength without increasing your size. Bodybuilders often neglect the slow twitch muscle fibers since they don’t help to achieve the look they want.

Personal trainers advise that if you want a lean and toned look, you should try to do more repetitions with less weight.