Movement Time and RFD

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Do curso por University of Florida

Science of Training Young Athletes Part 2

31 classificação

University of Florida

Science of Training Young Athletes Part 2

31 classificação

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.

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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.

Introduction3:51

Two Approaches3:43

Relevant Muscle Groups4:55

Movement Time and RFD7:04

Type of Resistance5:13

Movement Velocity2:32

Force-Posture Interaction9:43

Movement Direction2:25

Estimating Rate of Force Development8:05

Conheça os instrutores

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

Okay, so let's now discuss movement time and rate of force development and

why this is an important consideration when selecting assistant exercises.

I'm going to put up a curve here and

this curve shows the athlete's maximum force development.

Now the thing that you have to realize is that it takes 0.3 to 0.4 seconds for

the athlete to apply their maximum strength.

Zatsiorsky calls this the athlete's maximum strength or

their Fmm, which he refers to as their force maximum maximorum.

So it's an interesting term that I'll use.

I'm going to come back and talk more about the athlete's maximum strength or

their force maximum maximorum in a minute.

Now the time available to produce force in many sport

movements is usually between 0.08 to 0.18 seconds.

The athlete cannot summon their maximum strength in that particular time frame and

this is an important consideration when selecting assistance exercises.

In most sports, the athlete who can tap into more of their maximum

strength in the shortest amount of time usually has the upper hand.

And this depends on the maximum delivery force that I've got labeled here as Fm.

Now the maximum delivery force is the time it takes the athlete to reach

their maximum possible delivery force during their performance and

this is called the rate of force development.

High delivery force and very fast rate of force development in the lower body

is highly correlated with faster sprint speeds and greater jumping heights.

Neural activation and the firing frequency of the muscle fibers

is also a key to the athlete's rate of force development.

Okay, so on this slide then you have a couple of important points,

the maximum delivery force, which is Fm.

And you have the maximum force the athlete is capable of producing,

and that's their Fmm, or their force maximum maximorum.

Okay now, you can appreciate the importance of

delivery force by examining this table.

Throwing type movements, such as javelin and

shot put throwing takes around 0.15 to 0.18 to complete.

And pushing type movements, such as sprinting,

permit only 0.08 to 0.10 seconds to produce a force.

And long jumpers have 0.11 to 0.12 seconds and high jumpers have 0.18 seconds.

These are all very, very short times.

In all these cases the movement is

completed before the athlete can apply their maximum force.

Zatsiorsky, remember, refers to the athlete's maximum

force as the force maximum maximorum, or their Fmm.

And the maximum force, remember that an athlete can produce in the time

permitted to complete the movement is denoted here as Fm.

And this is the athlete's maximum delivery force and

it's always much lower than their maximum force production.

The difference between their maximum delivery force,

which is their Fm when they reach when completing a given sport movement,

that is their delivery force, remember.

And the maximum force the athlete can produce without considering the time

constraints, that is their Fmm.

That is their force maximum maximorum.

This difference between those two different types of forces is

termed the explosive strength deficit.

In equation form the explosive strength deficit as a percentage is

equal to 100 times the Fmm minus the delivery force,

the Fm, and that's divided by the Fmm.

Now according to Zatsiorsky, only half the athlete's strength

potential is used when performing explosive movements.

For example, elite shot putters throw the shot around

21 meters and when delivering these shots they apply a peak force,

a delivery force of Fm of 50 to 60 kilograms.

Now their highest arm extension force that they can produce as measured by a one

rep max bench press is typically 220 to 240 kilograms.

That is, it's about 110 to 120 kilograms per arm.

That's their Fmm.

Therefore, the elite shot putters are using about 50% of their potential

maximum arm extension force, their Fmm, while they are throwing the shot.

And this is about as close as any athlete can come.

The value of improving an athlete's maximal force, or

their force maximum maximorum, to improve their performance then,

depends on where they are on the experience scale.

When an inexperienced shot putter increases their arm extension strength,

they're throwing performance typically improves.

Advanced shot putters, on the other hand, who already have superior arm extension

strength, do not benefit much by increasing their arm strength further.

It's better that they look at their rate of forced development during the delivery

phase for throwing and improve that ability, so

that they can use their maximum arm force in a better way.

The athlete's maximum explosive strength, or rate of force development by

putting the shot, is a much more critical factor than their total maximum strength.

And we're going to return to rate of force development and

I'll show you how to estimate it for each athlete.

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