Are you better at quick bursts of energy or endurance exercise?

If you can identify correctly which you are better at you can create a custom wellness program that will take advantage of your natural abilities and propel you further than you thought possible.  Which leads to a question a client recently asked me.

Q: What is the difference between fast twitch and slow twitch muscle fibers?

A:  The two type of muscle fibers are fast and slow.  Most of us have 50% of each type. These fibers react differently to cardio and weight lifting. Slow fibers are more effective at aerobic exercise, thus it is more effective at using oxygen for continuous extend muscle contractions over a long time. These fibers are great for long distance running and any other type of endurance training. 

Fast twitch fibers behave the opposite. They are anaerobic (without oxygen) and therefore use anaerobic metabolism to generate fuel.  Fast fibers are much more effective for quick bursts of energy such as weight lifting and sprints. These fibers fatigue much quicker than their slow counterparts. 

Both fibers generally generate the same amount of force, but fast twitch fibers fire their force quicker than slow fibers, thus getting their names fast and slow twitch fibers. 

Interestingly, Olympic sprinters have been shown to have 80 percent fast twitch fibers while marathon runners tend to possess 80 percent slow twitch fibers.

Have you ever wondered why chicken breasts are white and their legs are dark?

Slow twitch fibers are red because they contain myoglobin (which carries oxygen), and fast twitch are white. Chickens are ground dwelling birds so they need to walk long periods of time.  This requires slow twitch muscles so they won’t fatigue over a long period of time. That is why you get the dark color.  The wings and breast are used for a quick flight response from danger.  This requires fibers that respond to quick bursts of energy. So they need fast twitch fibers, resulting in white meat.

Now you didn’t ask; but, me, I can go for longer periods of exercise than Ryan. He has me beat in sprints and weightlifting. So from that you could reasonably think that I’m dark meat and he’s white meat. Just another example of opposites attracting!