In running you have all seen the #sprinter and the #marathoner. One looks like an 80’s #actionstar while the other looks like he hasn’t eaten for weeks. They are both #runners so how come they don’t look alike???

Simple, they #practice different #sports . It’s #explosivestrength (sprinter) vs #endurance (marathoner). The #answer is in the way these #athletes train their #muscles .
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The muscles contain 2 types of fibers:
1: Fast Twitch
2: Slow Twitch.
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A sprinter will primarily train his fast twitch fibers. These react instantly and work #superfast but quickly run out of #power. When trained fast twitch fibers #naturally become #bigandheavy . While on the other hand, a marathoner primarily trains his slow twitch fibers. These are not as reactive and speedy as their fast twitch brother but they can work #nonstop for hours. When trained these fibers remain #slim and #light .
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The running capability of both athletes don’t only depend upon the #physique of their #legs , the #upperbody is also important. For the sprinter to be able to burst from the starting line and maintain a good rhythm while running, he needs #balance and that’s why his upper body should have a considerable size as well. So he also comes off his upper body in the gym and that’s why he looks so #muscular. Also the sprinter has to run for only a few seconds therefore the added weight is trivial.
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But for the marathoner it’s a different #story. Every #pound in his #body has to carried around for #kilometers. He gains a lot of benefits by being light. So in order to become a top marathoner all the excess fat and muscle mass has to be shed. That’s why marathoners are #skinny .
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Apart from their training #genetics also play a part. A normal person have equal amount of fast twitch and slow twitch fibers. But the persons that make it to the top tend to have more of one kind. So even untrained they won’t have the same physical appearance.
The sprinter and the marathoners are both runners yet different athletes.