Presentation ---Movement & Support Group 5 Chen Xinlu Lu Wei Hu Zhenzhen He Shanliang Min Tue

Comparing Their Muscles… Marathon runners Sprinters

The Topic Are there any physiological differences between the muscles of a marathon runner & a sprinter?

Two Kinds Of Runners There are two kinds of runners: long-distance runners (marathon runners) and short-distance runners (sprinters). Long-distance runners seem to have no trouble running for hours till the end. On the other hand, short-distance runners are built for explosive, all-out, high speed performance over short distances.

Recall: The Muscle Fibers Skeletal muscle is made up of thousands of cylindrical muscle fibers often running all the way from origin to insertion.

Skeletal Muscle Types Twitch Speed Generation of Force Fatigue Resistance Fuel Source Type I Fibers Slow Low High Triglycerides Type IIa Fibers Fast Medium Glycogen Type IIb Fibers Very Fast Very High Type I muscle fibers are needed for long distance. Type II a and Type II b muscle fibers are needed for power and speed.

The slow twitch fibers are red due to their high concentration of blood capillaries, this results in greater blood supply and in turn greater oxygen supply to the working muscles. Due to their low-oxidative demand, fast twitch fibers have low levels of mitochondria and myoglobin, and thus appear white. Slow twitch in red fast twitch in white.

Type I (slow oxidative)                                                                              Type I (slow oxidative) Type IIa (fast oxidative) Type IIb (fast glycolytic) Human muscles contain a genetically determined mixture of both slow and fast fiber types. On average, we have about 50% slow and 50% fast fibers in most of the muscles used for movement.

Continue… A lot of fast twitch fibers can be an asset to a sprinter when there is a limited amount of time to generate maximal force The slow twitch fibers, on the other hand, fire less rapidly, but can go for a long time before they fatigue.

The characteristic of one’s muscle fibers is largely inherited. But there is some evidences that training can make a small difference to the proportions of the different fiber types.

Changing In The Muscle Fibers The ratio of Type I to Type II muscle fibers is genetic; they were that way since birth. Only the ratio of Type II a to Type II b can be changed.

Marathon Runner Distance running will gradually change the Type II b muscle fibers into Type II a. The more a marathon runner runs, the more his/her muscles will change into long-distance performers. A marathon runner must avoid any sprint training at distances less than 100m.

Sprinter A sprinter, need to maximize the size of those Type II b muscle fibers. A explosive sprinter should do weight training and polymeric exercise to get big and beefy muscles and must never engage in endurance exercise.

Thanks For Your Kind Attention!!! References http://bicycling.about.com/od/training/l/aa021703a.htm http://www.bbc.co.uk/science/hottopics/marathon/ www.bodybuilding.com/ fun/other21.htm http://en.wikipedia.org/wiki/Muscle_fiber