A typical myth in bodybuilding circles is that you must exercise fast and slow twitch muscles separately for getting the best muscle building workout. This could not be further from the truth. In fact, you can easily exercise both muscle types at the same time and still get excellent results. Here is why and what you should do in your own workouts for optimum results.
Slow twitch muscles are the simplest to describe. They are powerful aerobically, meaning good at using oxygen. They are called slow twitch because they are slow to fatigue, not because they are slow to contract. Being slow to fatigue makes this type of muscle fiber important for endurance. These fibers recover fast after being fatigued. Slow twitch muscle fibers are useful to long distance runners and other endurance athletes.
In contrast, fast twitch muscles are a bit more complicated. They are classified into three separate subgroups. The first subgroup, the Fast Oxidative fibers, work best in the presence of oxygen and are the slowest to fatigue. The second subgroup, the Fast Glycolytic fibers, operate mostly in the absence of oxygen (i.e., anaerobically). They are the fastest to fatigue and the slowest to recover. The third subgroup is right in between, called the Fast Oxidative Glycolytic fibers. Keep in mind that fast twitch are so called because they fatigue fast. Then they are very slow to recover.
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 fiber action based on force rather than the speed of contraction. This is why slow twitch muscles are the first type to engage when the most force is needed. They also do not need as much energy to deliver their force. This just means that when you lift weights too rapidly, you will engage primarily your slow twitch muscles.
A bit more energy is required to power up the Fast Oxidative muscle fibers. Still more energy is required to engage the Fast Oxidative Glycolytic fibers. The greatest amount of energy, however, is required by the Fast Glycolytic muscle fibers.
The key to the best workouts, therefore, is to follow the advice of physiologists to take advantage of what they call orderly recruitment of muscle fiber types. Orderly recruitment means to engage each type in sequence, from low energy/fast recovery to high energy/slow recovery. The most important components of such a workout are: 1) sufficient weight to bring on muscle failure (i.e., enough that at some point you can no longer lift); 2) the right speed of lifting for recruiting all fiber types in sequence; and, 3) the total time under load (TUL) for each 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 approach recommended here is backed up by many scientific research studies over the past few decades. The best summary of these studies is provided in a book, 'Body by Science', by Dr. Doug McGuff, M.D., and John Little. It is the best and most thorough book on this topic. Interestingly, the subtitle of this book is, 'A Research-Based Program for Strength Training, Body Building, and Complete Fitness in 12 Minutes a Week'. In fact, based on my experience, 12 minutes a week is more than enough. My personal muscle building workouts have yielded tremendous results in just under 10 minutes per week on average.
Slow twitch muscles are the simplest to describe. They are powerful aerobically, meaning good at using oxygen. They are called slow twitch because they are slow to fatigue, not because they are slow to contract. Being slow to fatigue makes this type of muscle fiber important for endurance. These fibers recover fast after being fatigued. Slow twitch muscle fibers are useful to long distance runners and other endurance athletes.
In contrast, fast twitch muscles are a bit more complicated. They are classified into three separate subgroups. The first subgroup, the Fast Oxidative fibers, work best in the presence of oxygen and are the slowest to fatigue. The second subgroup, the Fast Glycolytic fibers, operate mostly in the absence of oxygen (i.e., anaerobically). They are the fastest to fatigue and the slowest to recover. The third subgroup is right in between, called the Fast Oxidative Glycolytic fibers. Keep in mind that fast twitch are so called because they fatigue fast. Then they are very slow to recover.
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 fiber action based on force rather than the speed of contraction. This is why slow twitch muscles are the first type to engage when the most force is needed. They also do not need as much energy to deliver their force. This just means that when you lift weights too rapidly, you will engage primarily your slow twitch muscles.
A bit more energy is required to power up the Fast Oxidative muscle fibers. Still more energy is required to engage the Fast Oxidative Glycolytic fibers. The greatest amount of energy, however, is required by the Fast Glycolytic muscle fibers.
The key to the best workouts, therefore, is to follow the advice of physiologists to take advantage of what they call orderly recruitment of muscle fiber types. Orderly recruitment means to engage each type in sequence, from low energy/fast recovery to high energy/slow recovery. The most important components of such a workout are: 1) sufficient weight to bring on muscle failure (i.e., enough that at some point you can no longer lift); 2) the right speed of lifting for recruiting all fiber types in sequence; and, 3) the total time under load (TUL) for each 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 approach recommended here is backed up by many scientific research studies over the past few decades. The best summary of these studies is provided in a book, 'Body by Science', by Dr. Doug McGuff, M.D., and John Little. It is the best and most thorough book on this topic. Interestingly, the subtitle of this book is, 'A Research-Based Program for Strength Training, Body Building, and Complete Fitness in 12 Minutes a Week'. In fact, based on my experience, 12 minutes a week is more than enough. My personal muscle building workouts have yielded tremendous results in just under 10 minutes per week on average.
About the Author:
Dr. Dennis Clark researches, reviews, and provides science-based advice on bodybuilding foods in his popular free report on the muscle building diet. Dr. Clark also offers tips on where to find the best bodybuilding supplements anywhere.
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