Muscle Fiber and Training

We all have three types of skeletal muscle fibers. Many people know them as slow or fast twitch fibers. Today they are commonly referred to as Type I or Type II fibers and Type II as two types A and B.

Type I or slow twitch are resistant to fatigue and are considered endurance fibers. These fibers the ones that provide the work when you go for a long walk or jog, swim or ride your bike. Elite endurance athletes, like the cyclists who compete in the Tour de France may have as much (or more) as 70% of their sketital muscle fiber as Type I.

We have two types of Type II fibers. Type A, are used when we work for about three minutes continuously and Type IIB are our most powerful fibers. Our IIB fibers are the power fibers, the ones we use for powerful short bursts of work. These fibers will fatigue in about ten seconds or less and are predominate in elite 100 Meter sprinters.

Here is the training issue. As we age we lose muscle fiber and if we don’t work our muscles we loss them faster. The problem is many do not train our Type IIB fibers. Many people when they train they lift light weights at a high repetition. That’s fine for those Type I fibers but what about the type II. I know many are thinking that I don’t sprint or do and short powerful movements “at my age.” Well yes you do. When people become elderly one of the biggest fears we have is falling. Some are afraid of breaking a bone others don’t know if they will be able to get up.

So lets think about falling. When people fall, studies indicate that it is for two reasons. First, slow dorsi flexion of the foot (ankle) or lifting your toe quickly at the ankle. Well that is a short burst of power and people fall because they can’t get their toe up fast enough to get it under themselves and regain their balance. The second reason we fall is a slow movement at the hip (flexion). We don’t get our knee up quick enough to clear the ground so we can dorsi flex our foot. Both of these movements are quick bursts of powerful movement. Lifting your knee and toe take less time than running 100 meters.

Why does this happen because we have lost (due to lack of training) or don’t train our dorsi flexors of the foot or our hip flexors to “move quickly.”

Now what about getting up. The movement of putting your hands on the ground and pushing yourself up is power. You have just become a power lifter. You are what you need to lift. Think about watching a baby begin to crawl. They lift up their head and body, drive their knee under their chest and push forward. Now think about pushing yourself up and moving your knee under yourself. It’s the same primal movement. Now if you’re not sure that these movements are power movements, visualize a sprinter at the start of the race. They “crawl” out of the blocks. Crawling is the movement that leads to sprinting.

So next time you go to the gym or class ask your trainer how to work those Type II fibers it may help you avoid breaking a hip