A common bodybuilding myth says that fast and slow twitch muscles must be exercised separately for the best muscle building workout. This is not true. You can build strength in both types at the same time. Here is the why and how behind this truth.
The simplest type of muscle fibers to describe are the slow twitch muscles. They derive their power from the efficient use of oxygen. They are named slow twitch after how slow they are to get fatigued, which has nothing to do with their speed of contraction. They are particularly importance for endurance. These types of fibers also recover very fast once they have become fatigued. This is the reason why they are so important for endurance athletes such as long distance runners and cyclists.
Fast twitch muscles are more complicated, because they are classified into three subgroups. One is the Fast Oxidative fibers, which are good aerobically and are resistant to fatigue. Another type is Fast Glycolytic, which includes fibers that are more effective anaerobically (without oxygen transfer). They are the easiest to fatigue and the slowest to recover. The third type is intermediate, referred to as Fast Oxidative Glycolytic. The fast twitch muscles are so called because they fatigue fast. However, they recover slowly after being fatigued.
These are simplified descriptions of how muscle fibers are classified based on their ability to use oxygen and on the speed at which they fatigue and recover from fatigue. Slow twitch muscles actually twitch faster and recover faster from exercise than do fast twitch muscles.
Muscle fibers are recruited by your brain to optimize force and not speed of contraction. Because of this, slow twitch muscles are the first and easiest fiber type to engage. This type also requires the least amount of energy. This means that if you lift weights too quickly, you will engage mostly your slow twitch muscles.
A little more energy is necessary to engage the Fast Oxidative muscle fibers. Even more is necessary to engage the Fast Oxidative Glycolytic fibers. And the largest amount of energy is required for engaging the Fast Glycolytic fibers.
The key for an optimum workout, therefore, is to take advantage of what physiologists call orderly recruitment. This means engaging each type of muscle fiber in sequence, from low energy and fast recovery to high energy and slow recovery. The important factors for accomplishing this in the same workout are: 1) sufficient weight for bringing on muscle failure (i.e., the point at which you can no longer lift the weight); 2) the right lifting speed for engaging all types of muscle fibers in sequence; and, 3) the total time under load (TUL) for a particular set or muscle group.
The optimum strategy for accomplishing all of the above entails a very slow lift rate and an equally slow return rate. One extra advantage of such super slow movements is that it is easier to use good form. Fast lifting leads to jerking weights rather than lifting them. Jerking weights merely recruits mostly slow twitch muscles and leaves other fiber types unchallenged.
The recommendations here are backed by many scientific studies over the past few decades. The best summary of this research is now available in the book, 'Body by Science', by Dr. Doug McGuff, M.D., and John Little. It is the best book that I have found on the subject. Oh, and the subtitle the book is very intriguing: 'A Research-Based Program for Strength Training, Body Building, and Complete Fitness in 12 Minutes a Week'. However, based on my experience, 12 minutes a week may be more than you really need. My own results with the Body by Science approach have been great on only about 10 minutes a week of total workout time.
The simplest type of muscle fibers to describe are the slow twitch muscles. They derive their power from the efficient use of oxygen. They are named slow twitch after how slow they are to get fatigued, which has nothing to do with their speed of contraction. They are particularly importance for endurance. These types of fibers also recover very fast once they have become fatigued. This is the reason why they are so important for endurance athletes such as long distance runners and cyclists.
Fast twitch muscles are more complicated, because they are classified into three subgroups. One is the Fast Oxidative fibers, which are good aerobically and are resistant to fatigue. Another type is Fast Glycolytic, which includes fibers that are more effective anaerobically (without oxygen transfer). They are the easiest to fatigue and the slowest to recover. The third type is intermediate, referred to as Fast Oxidative Glycolytic. The fast twitch muscles are so called because they fatigue fast. However, they recover slowly after being fatigued.
These are simplified descriptions of how muscle fibers are classified based on their ability to use oxygen and on the speed at which they fatigue and recover from fatigue. Slow twitch muscles actually twitch faster and recover faster from exercise than do fast twitch muscles.
Muscle fibers are recruited by your brain to optimize force and not speed of contraction. Because of this, slow twitch muscles are the first and easiest fiber type to engage. This type also requires the least amount of energy. This means that if you lift weights too quickly, you will engage mostly your slow twitch muscles.
A little more energy is necessary to engage the Fast Oxidative muscle fibers. Even more is necessary to engage the Fast Oxidative Glycolytic fibers. And the largest amount of energy is required for engaging the Fast Glycolytic fibers.
The key for an optimum workout, therefore, is to take advantage of what physiologists call orderly recruitment. This means engaging each type of muscle fiber in sequence, from low energy and fast recovery to high energy and slow recovery. The important factors for accomplishing this in the same workout are: 1) sufficient weight for bringing on muscle failure (i.e., the point at which you can no longer lift the weight); 2) the right lifting speed for engaging all types of muscle fibers in sequence; and, 3) the total time under load (TUL) for a particular set or muscle group.
The optimum strategy for accomplishing all of the above entails a very slow lift rate and an equally slow return rate. One extra advantage of such super slow movements is that it is easier to use good form. Fast lifting leads to jerking weights rather than lifting them. Jerking weights merely recruits mostly slow twitch muscles and leaves other fiber types unchallenged.
The recommendations here are backed by many scientific studies over the past few decades. The best summary of this research is now available in the book, 'Body by Science', by Dr. Doug McGuff, M.D., and John Little. It is the best book that I have found on the subject. Oh, and the subtitle the book is very intriguing: 'A Research-Based Program for Strength Training, Body Building, and Complete Fitness in 12 Minutes a Week'. However, based on my experience, 12 minutes a week may be more than you really need. My own results with the Body by Science approach have been great on only about 10 minutes a week of total workout time.
About the Author:
Dr. Dennis Clark shares his expertise on how to eat for bodybuilding in his popular free report on the muscle building diet. Also see what Dr. Clark has to say about where to find the best bodybuilding supplements anywhere.
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