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When you look at the human shape and compare the huge variations to different sports, the research in this subject is not very good. There are exceptions at some of the extreme ends of some shapes, but overall there are too many other factors that athletes have that makes some of the assumptions invalid. People are short, medium height, tall, thin, muscular, fat, obese, and combinations of those. You have short and fat, short and thin, tall and fat, tall and thin, muscular and short, etc. for body types.
During one year in college working on a degree, there was a professor that was sure she could come up with a formula that would predict the body shape and what sport the athlete would excel in. She took photographs of incoming freshman women and graded them as ectomorph (skinny), mesomorph (muscular), and endomorph (fat). She then followed their careers for four years of competing. The result was that there were so many discrepancies in the various sports that no conclusion could be reached and the research had no outcome relating body type and success in a particular sport.
There are some factors in body shape that lend themselves to a better chance to succeed in a specific sport. David Epstein, author of ‘The Sports Gene’, wrote about studies that were done on marathon runners from the Kalenjin tribe in Africa and why this group is so successful in running the marathon. The main focus of the research was on the physical characteristics that favor running long distances fast.
Several physical characteristics in Kalenjin runners versus other runners demonstrated why they were at an advantage both physically and biomechanically. The report likened the difference to how most people look at cars. You have big engines and economic engines. Most people know that a big car with a big engine to go fast will usually have low gas mileage. A smaller, lighter car will have a smaller engine but have good gas mileage. It seems that the Kalenjin runners had the big engine (aerobic capacity) and good fuel economy (can run long distances faster and have better biomechanical efficiency).
One study showed that even though the Kalenjin runners were two inches shorter than the Danish counterparts, their leg length was three-fourths of an inch longer. The volume and thickness of the lower legs of the Kalenjin boys was 15-17% less than the Danish boys. One other difference between the two groups was that the Kalenjin runners had a slightly longer Achilles tendon. The longer Achilles tendon provided more power with each stride during running. They also seemed to have a higher aerobic capacity that enabled them to exert less energy when running fast in a marathon.
The value of weight distribution in the body was demonstrated in a study where weight was placed on a runner’s waist, upper thigh, upper shin, and ankle. Wearing eight pounds around the waist required about 4 percent more energy than if there was no weight attached. The big difference was noticed when four pounds was attached to each ankle and the energy expenditure burned around a level of 24 percent. This is called “distal weight,” and like any pendulum with weight on the end, requires more energy. One study showed that adding 1/10th of a pound to an ankle increased oxygen consumption by 1 percent. The Kalenjin runners had nearly one pound less weight in their lower legs than the Danish runners. This amounted to about 8% energy saving per kilometer (a marathon is 42 kilometers). This is where shoe manufactures develop that racing flat shoe that is light in weight. The statement that a runner with thick calves and ankles will never win the New York Marathon applies in this instance. Looking back at elite marathon runners, I can recall only Rob DeCastella as having muscular legs and still managed to be near the top finishers in a marathon.
Elite long-distance runners have both high VO2 max (aerobic capacity) and good running economy. In other words, they have big engines and great fuel economy. Running economy often differentiates the extremely great from the merely good.
There is one other physical characteristic that determines where an athlete will excel at speed or endurance sports. There are roughly three types of muscle fibers. There is fast twitch muscle fibers that contract fast and are necessary for speed. There are slow twitch muscle fibers that are good for endurance sports. Most of us fall in the range of 60% - 70% of one or the other. This is a medium twitch muscle fiber and can be trained to go either way – just not to the level of an athlete that has 80% - 90% of one or the other muscle fibers. The majority of athletes can develop into good athletes with training. They will never be the Olympic Champion caliber athletes, but can be very successful in their sport.
The main point of this for the large majority of us is that have fun at your sport, be the best that you can be, and don’t worry about that runner with skinny calves.
