Muscle Fiber Types

There are two major types of muscle fibers,fast twitch and slow twitch. There are additional sub-types but for our discussion here we will focus on the two major types. Exercise of short duration requiring power and strength is performed by the fast twitch and exercise of longer duration is performed by the slow twitch fibers. Fast twitch fibers,not surprisingly, are responsible for most of the hypertrophy,or muscle size increases in a muscle. Weight training sets which last for 20-60 seconds are best for training this type. Sets lasting 90-120 seconds are best for training the slow twitch fibers. Most people have muscles that have a combination of fiber types. These muscles are best trained with sets lasting a total of 60-90 seconds. The best way to find out which type of fiber(s) your muscles contain is to find out what the maximum weight you can lift in a particular lift is and after ample rest of five minutes or more,load the bar or machine with 80% of your 1RM. Preferably this is done with an isolation exercise so that the focus is on only one muscle at a time. Do as many reps as you can until you can do no more. If you can only do less than seven reps you have predominately fast twitch fibers. If you can do 7-10 reps you have a mixture of both and if you can do more than that you have mostly slow twitch fibers. You then can tailor your training for your particular muscle fiber type. I will go into more specifics on that next. For more info on HIT Training and for services I offer both in person and through the Internet please see my website:www.personal-resistance-trainer.com