Genetics and Muscle Fiber Basics



They say thatgenetics plays a big part in building your body. What exactly in your body isit that the genetics control? Part of it is the muscle fibers and the type offibers that your muscles are composed of. To fully develop, build and shape abody, you have to understand the building blocks a muscle is composed of.

Many people flock to the personal trainer sporting the biggest arms thinkingthat because of his development he has the best knowledge of building a body.Nine out ten times, he doesn't. Why? The majority ofthose types of people have a specific body type and predominance of a specificmuscle fiber type that is predisposed genetically to be large and respond toweights. If these genetically blessed only lifted one-pound bricks they'd stillhave 19 inch arms. How would they know how to develop a person who's beentraining hard and still has 13 inch arms? The bottom line is that just becausehe's got huge arms doesn't mean he has huge trainingknowledge. He may put you on their arm routine, which works for them, not you,because of their genetic makeup.

This is also why following a pro bodybuilder's routine is a waste of time.Their volume is sky high and they have a quick recuperation rate due to thevarious drug ****tails they're on. Following their program would just lead toovertraining and possible injury to the average Joe, who's not on 2,000mg aweek. I think the greatest testament to this philosophy is that the besttrainers usually don't look like a bodybuilder. The best trainers have in-depthknowledge of fiber type, how the muscle recruits those fibers during exercise,and how to maximally stress that physiology to initiate growth.

So how does this pertain to you? Well, first we have to find out what yourbody's muscles are made up of, since once that's determined we can moreeffectively design a workout program that will maximally develop your body andbring you one step closer to having your total physique. When you're born, goodol' mom and dad blessed or cursed you with a certain predominance of musclefibers. It's why in athletics you were either going to be a football player ora cross-country runner. In other words, if you were blessed with a high levelof Type IIa and Type IIb muscle fibers you were ready to be a fullback, and ifyou were blessed with a high level of Type I fibers you could run for mileseasily.

Type IIa and Type IIb are referred to as fast-twitch fibers. They are able toproduce great amounts of power, are larger in size and fatigue easily. Thetypical bodybuilder muscle guy has a lot of Type IIb fibers, since those arethe largest and able to produce the most force. Type IIa fibers are a littlesmaller, but have more endurance then Type IIb.

Type I fibers, are referred to as slow-twitch fibers, also known as your"marathon fibers". They are smaller in size than Type II fibers, havea very high aerobic capacity and take a long time to fatigue. Long-distancerunners typically have Type I fiber dominance. Your typical "skinnyguy" that can never get big, no matter how heavy they lift, also has TypeI muscle fiber dominance.

Now, there are the lucky ones out there with perfect ratios of fiber types. This type of individual has a body that easily responds to athletics and weighttraining and every muscle develops just perfectly.

The majority of people have a little of both muscle fibers; a few body partsthat develop easily and others that lag. The easiest example that comes to mindis the guy with big arms and small calves. With a little understanding ofmuscle physiology and how fiber type and recruitment comes into play, that guywill have calves closer to match his arms, and the thin guy can start to see amuscular body develop.

Genetics can't be changed, but you can work with what you're given instead ofworking against it and becoming frustrated with your body. Fighting yourgenetics won't get you closer to a total physique, but understanding them,will