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MidlandBDog
05-19-2007, 03:53 PM
I hear alot about the difference in slow and fast muscle fibers. they say fast twitch muscles are what mak you muscles move faster but slow twitch is for strength and endurance. i was hoping for some input on what to do do to build fast twitch leg muscle fibers for speed for football.

JHarris
05-19-2007, 04:51 PM
I hear alot about the difference in slow and fast muscle fibers. they say fast twitch muscles are what mak you muscles move faster but slow twitch is for strength and endurance. i was hoping for some input on what to do do to build fast twitch leg muscle fibers for speed for football.

This is not exactly correct. Looking at the types of muscle fiber in skeletal muscle in the simplest way, there are Type I fibers (slow twitch) and type II fibers (fast twitch). When you recruit a particular muscle for an activity, you recruit some percentage of your fibers. Fibers work on an all or nothing principle, so if you are lifting, say 50% of your max, you are not engaging a large number of your muscle fibers.

Type II fibers are higher threshhold fibers. They let you be fast, powerful and strong. Regardless of whether or not you are trying to jump for maximal height, run really fast or lift a VERY heavy weight slowly, you are likely engaging these fibers.

Type I fibers are your endurance and day to day fibers. They can stay contracted longer without fatiguing, but they do not have nearly as high of a capacity for strength and speed of contraction.

Consequently, if you want to train to be faster/strong, you have to work at higher percentages of your maxes so that you can actually recruit the type II fibers (80% +). Alternatively, if you are more advanced you can work at lower percentages but with lots of speed. However, I would recommend having excellent form before trying either of these methods. Form is more important than intensity.

For football, running form can help a lot, as can practicing sprints. The olympic motions are great, as are the basics - heavy squatting and deadlifting. The current theory is that hamstring strength correlates more highly with running speed, so don't neglect your deadlifts. They'll also protect you from hamstring pulls since you won't be as likely to have a bad quad/hamstring strength in balance.

Jay