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.
On the other hand, fast twitch muscles are more complicated to describe, because they are categorized into three different subgroups. The Fast Oxidative fibers are powerful aerobically and the most resistant to fatigue. In comparison, Fast Glycolytic fibers, which are more effective anaerobically (i.e., without oxygen transfer), are the easiest to fatigue and the slowest to recover. The third type is in between these two, called the Fast Oxidative Glycolytic fibers. Remember that fast twitch fibers are called fast because they fatigue fast. Then they recover very slowly.
Although these are pretty simple descriptions of different muscle fiber types, they give a preliminary picture of their relative use of oxygen and how fast they can recover from exercise. In fact, slow twitch muscles contract faster and recover faster than do any of the other types of muscle fibers.
Your brain recruits muscle fibers for force rather than speed of contraction. For this reason, slow twitch muscles are the easiest fiber type to engage. They also require the least amount of energy. In fact, if you lift weights too quickly, you primarily engage your slow twitch muscles.
Slightly more energy is required to engage the Fast Oxidative muscle fibers, and still more for the Fast Oxidative Glycolytic fibers. The highest amount of energy is required to engage 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 approach for accomplishing all this requires a very slow lift rate and an equally very slow return rate. Such super slow movements also encourage good form. Fast lifting, in contrast, often leads to bad form from jerking the weights instead of lifting them smoothly. In addition, jerking weights recruits mostly slow twitch muscles and fails to engage the other fiber types.
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.
On the other hand, fast twitch muscles are more complicated to describe, because they are categorized into three different subgroups. The Fast Oxidative fibers are powerful aerobically and the most resistant to fatigue. In comparison, Fast Glycolytic fibers, which are more effective anaerobically (i.e., without oxygen transfer), are the easiest to fatigue and the slowest to recover. The third type is in between these two, called the Fast Oxidative Glycolytic fibers. Remember that fast twitch fibers are called fast because they fatigue fast. Then they recover very slowly.
Although these are pretty simple descriptions of different muscle fiber types, they give a preliminary picture of their relative use of oxygen and how fast they can recover from exercise. In fact, slow twitch muscles contract faster and recover faster than do any of the other types of muscle fibers.
Your brain recruits muscle fibers for force rather than speed of contraction. For this reason, slow twitch muscles are the easiest fiber type to engage. They also require the least amount of energy. In fact, if you lift weights too quickly, you primarily engage your slow twitch muscles.
Slightly more energy is required to engage the Fast Oxidative muscle fibers, and still more for the Fast Oxidative Glycolytic fibers. The highest amount of energy is required to engage 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 approach for accomplishing all this requires a very slow lift rate and an equally very slow return rate. Such super slow movements also encourage good form. Fast lifting, in contrast, often leads to bad form from jerking the weights instead of lifting them smoothly. In addition, jerking weights recruits mostly slow twitch muscles and fails to engage the other fiber types.
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.
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Get Dr. Dennis Clark's free report on how to eat for bodybuilding in his popular muscle building diet now. Also see what Dr. Clark has to say about where to find the best bodybuilding supplements anywhere.
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