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There's a ridiculously simple way to build muscle, but most people either don't know it, or they're just too obstinate to embrace anything new. They're like strict government Constitutionalists – if it ain't in the bodybuilding version of the Constitution ("The New Encyclopedia of Modern Bodybuilding," written by founding father, A. Schwarzeneggar), they don't wanna' do it.
That's too bad because they're losing out on their constitutional right to bare big, bad-ass arms, along with big, bad-ass delts, pecs, quads, and the rest.
Maybe Chad Waterbury can present a case for them to adopt this one, simple change.
–TC
When your goal is to get bigger, stronger, or leaner, you must respect the nerves in your body.
A muscle without the nerve that controls it is a lifeless bundle of tissue. That's why physiologists rarely talk about muscles without mentioning the associated "motor neuron," the nerve that makes your muscle fibers contract. A muscle without a motor neuron is like a car without an engine.
The motor neuron's role is to give orders to the muscle fibers much like a commander gives orders to his soldiers. Muscle fibers always contract when the motor neuron sends a signal, just like a group of soldiers will always respond to their commander's order.
Adding muscle mass requires you to recruit and exhaust the largest muscle fibers. Similarly, getting stronger requires you to quickly recruit your biggest, strongest muscle fibers. And the best training programs to rip you up have a very high metabolic cost because they also recruit the most muscle fibers.
Of course, none of this muscle fiber recruitment is possible without a direct order from the brain down to your motor neurons. That's why it's essential to understand how your motor neurons, and other important nerves, work in order to supercharge your workouts – no matter what your goal is.
You must recruit your largest muscle fibers to get big and strong. And the only way to accomplish that is by recruiting more motor neurons.
Spinal Cord Anatomy
In order to get this discussion going in the right direction, it's important to first understand how the spinal cord and motor neurons are typically depicted in neuroscience textbooks.
The spinal cord is about the diameter of a human finger and it runs from the base of your skull down to your last vertebra. It contains millions of nerve fibers that transmit information to and from the limbs, organs, and brain.
Imagine I pulled out your spinal cord, lopped off the top part, and looked down into the portion where the motor neurons go out to your biceps (flexors) and triceps (extensors). And for the purposes of this discussion we'll say that you could visualize the descending nerve tract from your brain that communicates with your motor neurons. This is what you would see:
Here's what you need to know thus far. First, motor neurons originate in your spinal cord where they exit out to your muscles. Second, motor neurons receive constant input from your brain via a descending neural tract. When the input from this descending tract increases, it can recruit more motor neurons or tell those motor neurons to fire faster. In either case, the amount of force your muscles can produce increases.
Now, let's look at the history of motor neurons.
The Size Principle
How Motor Neurons Work
In 1965, Harvard physiology professor, Dr. Elwood Henneman released a landmark study on the function of motor neurons.(1) His team discovered that motor neurons with the smallest diameter required less electrical input to fire than one that's any bigger.
Motor neurons, and virtually every other nerve in your body, are constantly receiving information from other nerves, such as the descending neural tract from your brain.
Think of this constant nerve "talk" as background noise. Once that talk reaches a certain voltage, your motor neuron will fire. I'll use the sciatic nerve, the largest nerve in your body, to explain why this science is important to your training goals.
Imagine you grab a fistful of straws. That "bundle" is your sciatic nerve while the straws are the motor neurons. However, unlike the straws, your motor neurons all have a different diameter and this diameter determines its firing order.
For example, let's say a doctor jammed an electronic stimulator into your sciatic nerve. And let's say the tip of the stimulator is on the smallest motor neuron in your sciatic nerve. He would only need to turn his stimulator up to a certain, low voltage before that motor neuron would reach threshold and fire. At that point an electrical signal travels down the motor neuron to contract the muscle fibers it's associated with.
Now, here's where things get really important.
The Difference Between Small and Large Motor Neurons
Since this is the sciatic nerve's smallest motor neuron, it's connected to your smallest muscle fibers. Skinny motor neurons connect to skinny muscle fibers. Not only are the muscle fibers smallest in diameter, but also in bundle size.
So this motor neuron contracts a small bundle of, say, 50 small muscle fibers that produce very little force. A bundle of 50 muscle fibers, by the way, is very small. A single motor neuron that innervates your hamstrings muscles can contain a thousand muscle fibers.
Next, imagine the doctor inserted the electronic stimulator into your largest motor neuron. This nerve would require significantly more voltage to reach threshold since it's much fatter.
Since this is the largest motor neuron, it's connected to your largest muscle fibers (in diameter) and biggest muscle bundle. Fat motor neurons connect to fat muscle fibers. So this fat motor neuron might contract 1000 fat muscle fibers, which results in a large increase in force.
The outstanding text, From Neuron to Brain, sums this process by stating the following:
"Muscle contraction begins with the small motor units and progress to large (the size principle of motor unit recruitment) because small motor neurons are more easily excited than large motor neurons by a given synaptic input."(2)
In other words, a low level of input from your brain will only recruit the smallest motor neurons that are connected to your smallest muscle fibers. To recruit your largest muscle fibers and produce maximum force, it takes a lot of descending neural drive from your brain.
A life-threatening event will jack up your descending neural drive so high that you'll recruit every possible muscle fiber and this, in turn, will give you superhuman strength until you tear yourself apart.
Okay, let's recap.
Dr. Henneman's size principle states that the skinniest motor neurons require the lowest voltage to reach threshold, whereas the largest motor neurons require the highest voltage to fire.
And based on previous work by Drs. Eccles and Sherrington, we know that the skinniest motor neurons are connected to a small bundle of skinny muscle fibers (smallest motor unit) and the largest motor neurons are connected to a large bundle of fat muscle fibers (largest motor unit) (3).
Therefore, the smallest motor unit fires first, followed by progressively larger motor units as more force is required. Indeed, my graduate school bible, Principles of Neural Science: Fourth Edition, states in big, bold letters: "Motor units are recruited in fixed order."(4)
That's too bad because they're losing out on their constitutional right to bare big, bad-ass arms, along with big, bad-ass delts, pecs, quads, and the rest.
Maybe Chad Waterbury can present a case for them to adopt this one, simple change.
–TC
When your goal is to get bigger, stronger, or leaner, you must respect the nerves in your body.
A muscle without the nerve that controls it is a lifeless bundle of tissue. That's why physiologists rarely talk about muscles without mentioning the associated "motor neuron," the nerve that makes your muscle fibers contract. A muscle without a motor neuron is like a car without an engine.
The motor neuron's role is to give orders to the muscle fibers much like a commander gives orders to his soldiers. Muscle fibers always contract when the motor neuron sends a signal, just like a group of soldiers will always respond to their commander's order.
Adding muscle mass requires you to recruit and exhaust the largest muscle fibers. Similarly, getting stronger requires you to quickly recruit your biggest, strongest muscle fibers. And the best training programs to rip you up have a very high metabolic cost because they also recruit the most muscle fibers.
Of course, none of this muscle fiber recruitment is possible without a direct order from the brain down to your motor neurons. That's why it's essential to understand how your motor neurons, and other important nerves, work in order to supercharge your workouts – no matter what your goal is.
You must recruit your largest muscle fibers to get big and strong. And the only way to accomplish that is by recruiting more motor neurons.
Spinal Cord Anatomy
In order to get this discussion going in the right direction, it's important to first understand how the spinal cord and motor neurons are typically depicted in neuroscience textbooks.
The spinal cord is about the diameter of a human finger and it runs from the base of your skull down to your last vertebra. It contains millions of nerve fibers that transmit information to and from the limbs, organs, and brain.
Imagine I pulled out your spinal cord, lopped off the top part, and looked down into the portion where the motor neurons go out to your biceps (flexors) and triceps (extensors). And for the purposes of this discussion we'll say that you could visualize the descending nerve tract from your brain that communicates with your motor neurons. This is what you would see:
Here's what you need to know thus far. First, motor neurons originate in your spinal cord where they exit out to your muscles. Second, motor neurons receive constant input from your brain via a descending neural tract. When the input from this descending tract increases, it can recruit more motor neurons or tell those motor neurons to fire faster. In either case, the amount of force your muscles can produce increases.
Now, let's look at the history of motor neurons.
The Size Principle
How Motor Neurons Work
In 1965, Harvard physiology professor, Dr. Elwood Henneman released a landmark study on the function of motor neurons.(1) His team discovered that motor neurons with the smallest diameter required less electrical input to fire than one that's any bigger.
Motor neurons, and virtually every other nerve in your body, are constantly receiving information from other nerves, such as the descending neural tract from your brain.
Think of this constant nerve "talk" as background noise. Once that talk reaches a certain voltage, your motor neuron will fire. I'll use the sciatic nerve, the largest nerve in your body, to explain why this science is important to your training goals.
Imagine you grab a fistful of straws. That "bundle" is your sciatic nerve while the straws are the motor neurons. However, unlike the straws, your motor neurons all have a different diameter and this diameter determines its firing order.
For example, let's say a doctor jammed an electronic stimulator into your sciatic nerve. And let's say the tip of the stimulator is on the smallest motor neuron in your sciatic nerve. He would only need to turn his stimulator up to a certain, low voltage before that motor neuron would reach threshold and fire. At that point an electrical signal travels down the motor neuron to contract the muscle fibers it's associated with.
Now, here's where things get really important.
The Difference Between Small and Large Motor Neurons
Since this is the sciatic nerve's smallest motor neuron, it's connected to your smallest muscle fibers. Skinny motor neurons connect to skinny muscle fibers. Not only are the muscle fibers smallest in diameter, but also in bundle size.
So this motor neuron contracts a small bundle of, say, 50 small muscle fibers that produce very little force. A bundle of 50 muscle fibers, by the way, is very small. A single motor neuron that innervates your hamstrings muscles can contain a thousand muscle fibers.
Next, imagine the doctor inserted the electronic stimulator into your largest motor neuron. This nerve would require significantly more voltage to reach threshold since it's much fatter.
Since this is the largest motor neuron, it's connected to your largest muscle fibers (in diameter) and biggest muscle bundle. Fat motor neurons connect to fat muscle fibers. So this fat motor neuron might contract 1000 fat muscle fibers, which results in a large increase in force.
The outstanding text, From Neuron to Brain, sums this process by stating the following:
"Muscle contraction begins with the small motor units and progress to large (the size principle of motor unit recruitment) because small motor neurons are more easily excited than large motor neurons by a given synaptic input."(2)
In other words, a low level of input from your brain will only recruit the smallest motor neurons that are connected to your smallest muscle fibers. To recruit your largest muscle fibers and produce maximum force, it takes a lot of descending neural drive from your brain.
A life-threatening event will jack up your descending neural drive so high that you'll recruit every possible muscle fiber and this, in turn, will give you superhuman strength until you tear yourself apart.
Okay, let's recap.
Dr. Henneman's size principle states that the skinniest motor neurons require the lowest voltage to reach threshold, whereas the largest motor neurons require the highest voltage to fire.
And based on previous work by Drs. Eccles and Sherrington, we know that the skinniest motor neurons are connected to a small bundle of skinny muscle fibers (smallest motor unit) and the largest motor neurons are connected to a large bundle of fat muscle fibers (largest motor unit) (3).
Therefore, the smallest motor unit fires first, followed by progressively larger motor units as more force is required. Indeed, my graduate school bible, Principles of Neural Science: Fourth Edition, states in big, bold letters: "Motor units are recruited in fixed order."(4)
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