Stimulus for Muscle Hypertrophy

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From the course by University of Florida

Science of Training Young Athletes Part 2

29 ratings

University of Florida

Science of Training Young Athletes Part 2

29 ratings

In this course you will learn how to design the type of training that takes advantage of the plastic nature of the athlete’s body so you mold the right phenotype for a sport. We explore ways the muscular system can be designed to generate higher force and power and the type of training needed to mold the athlete's physical capacity so it meets the energy and biochemical demands of the sport. We also examine the cost of plasticity when it is carried beyond the ability of the body to adjust itself to meet the imposed training stresses. The cost of overextending plasticity comes in the form injuries and chronic fatigue. In essence, a coach can push the athlete’s body too far and it can fail. Upon completion of this course you will be able to assemble a scientifically sound annual training plan.

From the lesson

Sport specific strength and power

Training an athlete’s strength and power so it improves their sport performance is a challenging aspect of coaching. Here is the important knowledge you must have: First, you must understand the important terminology such as strength, torque, work and power. Second, you must be able to apply the principle of specificity and transfer of training effects to the athlete’s strength and power development. Third, you must know what peripheral structural adaptations and central adaptations you are trying to accomplish.

Introduction3:14

Muscle Structure Adaptations5:40

How a Muscle Hypertrophies3:30

Types of Muscle Fiber Hypertrophy3:56

Stimulus for Muscle Hypertrophy4:38

Fiber Type Hypertrophy1:53

Absolute Versus Relative Strength2:19

Physics of Strength and Weight2:34

Meet the Instructors

Dr. Chris Brooks
Instructor
Coaching Science Coordinator for USA Track and Field

How a muscle is stimulated to hypertrophy remains unestablished.

One theory is the energetic theory.

It's theorized that there is only a certain amount of energy available

to the muscle fiber, and this energy is used for two purposes.

One is to build protein that will be used by the muscle to enhance its structure,

and this is referred to as the athlete's adaptive reserve.

Now, adaptive reserve is a term used in cardiology to describe

the ability of the heart to increase muscle mass and cardiac function.

In its effort to protect itself from damage when under stress,

and it's being borrowed from cardiology,

the other use of energy is to perform muscular work.

And under resting and light exercise conditions,

there is sufficient energy available in a muscle's cell to

simultaneously perform both of these functions.

During heavy resistive exercise, however, a high proportion

of the energy in the cell is needed for performing muscular work.

And here is the work being done by the contractile actin and myosin proteins.

And a lot of ATP is needed to break the cross bridges here to

keep the actin-myosin contracting.

And this is the molecular motor of the muscle,

and when training is intense,

there's a lot of ATP needed for this task.

Okay, so here's a graph divided into workout and recovery cycle phases.

This is the workout phase, and it's shown here in blue,

and this is the recovery phase, this red dotted line here,

is the normal homeostasis in the cell.

Now, if the energy supply for the synthesis of protein

decreases when it's diverted to perform mechanical work,

then it follows that there is insufficient energy to resynthesize

proteins fast enough to match the damage being done to the actin-myosin,

protein synthesis will decline, as shown here by the green line.

Compounding the problem is that amino acid entry into

the muscle cell is depressed during exercise, and

this means that amino acids needed to build proteins will be in short supply.

The protein damage exceeds the ability of the cell to replace it,

because it does not have the necessary building supplies.

So let's now take a look at what happens during the recovery phase.

During recovery, energy is not being diverted to muscular work,

so there is more energy available for protein synthesis.

The red line here indicates how much energy for

protein synthesis increases when the athlete is in the recovery phase.

During recovery, there's more amino acids entering into the muscle's cell,

and this allows a higher rate of protein synthesis,

as indicated by the green dotted line.

This repeated process of high destruction of contractile proteins and

low energy during the workout,

followed by enhanced protein synthesis and energy during recovery,

is thought to result in a super compensation of muscle protein synthesis.

And this is similar to the way muscle glycogen is

supercompensated in response to endurance training.

Muscle glycogen is drained to a low level during training, and this stimulates

the brain to supercompensate the reserve of glycogen in the muscle's cell,

and this same activity happens in protein synthesis of a muscle fiber,

and this is how it supercompensates or gets bigger.

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