Know Your Muscles for Optimal Training!!!!

(http://www.brianmac.co.uk/energy.htm)

What many people don't know about the human body in terms of the muscular system is that their is more than one type of muscle fiber. Actually, the muscle fibers can be classified as Type I which is slow twitch and Type I which is fast twitch. From there you can further categorize Type II fibers into Type II-A and Type II-B.


Type I muscle fibers have the slowest-contractile speed, the smallest cross-sectional area, the highest oxidative (aerobic) capacity, and the lowest glycolytic (anaerobic) capacity. They contract slowly and are able to hold a steady paced twitch for long durations without fatigue. Type I muscle fibers are predominately used in endurance activities. Long distance runners, swimmers, and cyclists mostly use Type I fibers.


Type II-B muscle fibers have the fastest-contractile speed, the largest cross-sectional area, the lowest oxidative capacity, and the highest glycolytic capacity. They are ideally suited for short fast bursts of power. These muscle fibers are used in such activities as sprinting, power lifting, and bodybuilding. Type II-A muscle fibers are intermediate and their properties lay between types I and type II-B.


Now that we've gone over the fiber types, we need to look at the energy that your body uses to fuel your muscles. Nutrition is very important in muscle function because your body converts the food it takes in and converts it into usable energy to fuel the muscle, this is called ATP or Adenosine Triphosphate. ATP is the immediate source of energy for muscle contraction. The human body makes ATP readily available through the three energy systems: Creatine-phosphate system or ATP-PC system, glycolytic system and the oxidative system. 
1.) ATP-PC system produces ATP the fastest amongest the other energy systems but only gives us 5-8 seconds of ATP
2.) The Glycolytic system or the Lactic Acid system due to the production of lactic acid as a by product. This system usually lasts less than two minutes and is used in moderately intense exercise. This system uses glycogen to produce ATP in addition this system doesn't utilize oxygen thus being called anaerobic (w/o O2).
3.) The Oxidative System comes into play for activities lasting longer than two minutes. It produces the greatest amount of ATP but takes the longest to produce it. This system uses the three macronutrients (proteins, fats and carbohydrates) to produce ATP. Oxygen is needed for this system to produce ATP.


Since we know the muscle fiber types and how the energy systems work, here is how reps effect strength and the muscle fibers:

Overview	Growth In Muscle Fibers Below
Repetition Range	Type I	Type IIA	Type IIB	Strength Gains
1-2 repetitions	Very Low	Low	Low	Excellent
3-5 repetitions	Very Low	Low	Decent to Good	Excellent
6-8 repetitions	Very Low	Good	Excellent	Good
9-12 repetitions	Low	Excellent	Very Good	Good Within Rep R.
13-15 repetitions	Decent	Very Good	Decent to Good	Endurance
16-25 repetitions	Very Good	Diminishing	Low	Endurance
25-50 repetitions	Excellent	Low	Very Low	Endurance

(http://www.criticalbench.com/muscle-fiber-type.htm)

So as you can see, the best range for strength and definition is 1-8, while muscular endurance is 12-50 reps.