Ahhh yes one of my favorite topics. As someone who has run marathons, competed in Body Building competitions and fought in ring I have trained both ways.

Some people react more favorably to the more short duration, high power anaerobic exercise (such as sprinting or weight training) as compared to longer duration, low power aerobic exercise (such as walking or jogging). The main reason for this is muscle fiber type.

There are two main types of fibers in your muscles.

Slow Twitch: These are also known as Type I muscle fibers. They are responsible for long-duration, low-intensity activity such as walking or any other aerobic activity.

Fast Twitch: These are known as Type II fibers (they are divided further into Types IIA and IIB). They are responsible for short duration, high intensity activity. Type IIB fibers are built for explosive, very short-duration activity such as Olympic lifts. Type IIA fibers are designed for more moderate-duration, high-intensity work such as weight training.

The difference for some people is the ratio of slow twitch to fast twitch muscle fibers. A marathon runner may have 80% slow twitch fibers in his or her legs and, therfore, be an amazing aerobic athlete.

An athlete such as a sprinter may have 80% fast twitch muscle fibers in his or her legs and be an amazing anaerobic athlete. This type of person would not react favorably to aerobic exercise due to the high percentage of fast twitch fibers in their legs. They would tire quickly because most of their muscle fibers are designed for short bursts and, most likely, would lose motivation rapidly.

So how do you determine what is going to work for you the best?

For most of us we are not one extreme or the other, most of us mere mortals are a relative mix of the two major types of muscle type and therefor we can mix up our training and do a combination or do what we like the most.

Some of us will tend towards one type or the other though and this can be easily determined by looking at pictures of ourselves when we were younger (or should I say less fat) and our underlying body type was easier to see.

If you look at me as a teenager you can see that I was very slender and so I had more of the slow twitch fibres whilst my brother was more muscular so more of the fast twitch fibres.

Look at a picture of a marathon runner vs a sprinter ….which one do you look more similar too?