How the engine works

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Do curso por University of Florida

Science of Training Young Athletes Part 2

35 classificações

University of Florida

Science of Training Young Athletes Part 2

35 classificações

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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Chronic Fatigue Due to Overtraining

When an athlete is underperforming, and you don’t know why, suspect chronic fatigue due to overtraining as the prime contributing factor. Unfortunately, because we don’t fully understand chronic fatigue our knowledge about overtraining remains scant. Hans Selye’s General Adaptation framework suggests it is likely due to too much training and insufficient recovery that leads to a prolonged maladaptation of physiological systems and structures. In this module you are provided insight into chronic fatigue and its relationship to overtraining.

Introduction5:53

Nervous system components2:29

Dual innervation2:55

Reciprocal effect2:15

The vagus nerve3:01

Heart control evolution8:06

How the engine works4:58

Respiratory sinus arrhythmia5:30

Conheça os instrutores

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

So here's another view at how the highly evolved mammal engine that

demands really high energy resources is regulated by the autonomic nervous system.

The sympathetic nervous system permits the engine to have a variable speed

beginning at a heart rate of 100 beats per minute.

And the engine is naturally set to this speed.

The engine can be turbo charged by the adrenal medulla up

to around 200 beats per minute depending on the age of the athlete.

The older the athlete, the lower the turbo charge effect will be.

When the influence of the adrenal medulla is removed, the engine speed falls

back under the influence of the sympathetic nervous system.

However, the sympathetic nervous system

keeps the heart beating at a natural rate of 100 beats per minute.

And energies supplies in the body would quickly deplete at this heart rate

if some mechanism was not available to turn the engine down

to an idle mode when it was not needed.This is where

the nucleus ambiguus branch of the vagus nerve comes into play.

And nucleus ambiguus acts as a brake to cut the speed of the engine

to a more energy-efficient idle during times of rest and

low activity, or low levels of activity.

The brake acts quickly to slow things down.

And when it's running at idle speed,

this is referred to as being under very high vagal tone.

Now the brake can be just as quickly removed so that the engine

speeds up to the sympathetic nervous system speed almost instantaneously.

And this is an essential asset allowing the quick response to

a high metabolic demand.

Vagal tone is highest during resting situations, such as during sleep,

and is reduced when they're metabolically demanding states,

such as exercise and stress, and information processing.

So when your brain is working, you have a slightly higher heart rate.

In mammals, the ancient DMNX maintains its old slowing function.

But in a healthy athlete, the slowing effect of the DMNX is usually minimal.

It's not bought into play.

But if the athlete's sympathetic nervous system is fatigued due to overuse,

the DMNX has a higher influence on the athlete's engine.

And one effect of the overactive DMNX

is to cause expulsion of all undigested food in the gut.

This is the ancient survival strategy to reduce the energy

requirements of digestion.

Now, an overactive DMNX may be one reason why some

athletes experience diarrhea when they're overly anxious about a competition.

It's possible that the DMNX has

increased its activity in response to the stressful situation.

And the athlete is experiencing its ancient effects.

But It's unclear if that's what's going on in this particular case.

Now, the existence of both the nucleus ambiguus and

the DMNX can also explain the two types of heart rate responses

when an athlete is chronically fatigued due to over training.

And as you will soon learn, in some over trained athletes,

their heart rate is higher than normal, and

in other over trained athletes it's as much lower than normal.

And when heart rate is higher than normal,

the nucleus ambiguus is providing a lower braking effect on the heart and

the sympathetic nervous system is having a higher influence.

And when the heart rate is slower than normal, this possibly

indicates the sympathetic nervous system is fatigued or even exhausted.

And the DMNX is the next evolutionary line of defense.

A high vagal tone that slows the athlete's heart rate right down below their

normal resting heart rate reflects a fatigued sympathetic nervous system.

And in this case, the athlete is possibly quite seriously sick.

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