Control Mechanisms

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來自 University of Florida 的課程

Science of Training Young Athletes Part 2

34 個評分

University of Florida

Science of Training Young Athletes Part 2

34 個評分

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.

從本節課中

Acute fatigue during training and competition

Fatigue is a phenomenon we all experience. It is characterized by tiredness and the desire to rest. Whether the athlete likes it or not, fatigue serves a protective function. It is both cognitive and physical in nature. In this topic you are introduced to the science of acute fatigue due to training and competition. With rest, acute fatigue dissipates and the body becomes stronger. You will learn about important fatigue theories, and the factors believed to contribute to fatigue such as low fuel supplies, acidity and body temperature.

Introduction5:55

Control Mechanisms5:10

Heat Adaptation3:38

Training Safely4:16

Exposure to Cold3:01

與講師見面

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

Thermoregulation is a term used to describe body temperature

control mechanisms.

So, protein structures and the brain are not damaged.

Thermoregulatory control structures and

processors are designed to keep the body core from becoming too hot or too cold.

Normal core body temperature is 37 degrees centigrade or

98.6 degrees Fahrenheit.

Core body temperature above 45 degrees centigrade destroys protein structures.

Now, enzymes are made from proteins and are particularly susceptible to heat.

And when too many enzymes are damaged, death can occur.

When core body temperature falls below 34 degrees centigrade or

93.2 degrees Fahrenheit, metabolism slows way down.

A slow metabolism disturbs heart activity and can also lead to death.

In other words, the temperature homeostasis for

effective body functioning falls within a very, very small range.

Core body temperature is regulated through two parallel control processes.

One is behavioral and the other is physiological.

The physiological control apparatus involves peripheral and

central structures.

The skin and the sweat glands are the peripheral control apparatus and

the brain, especially the hypothalamus is the central regulation structure.

The hypothalamus is the main central structure responsible for

balancing heat production with the heat loss of the body, so core temperature

remains within a safe range for proteins and the brain's electrical signaling.

The anterior hypothalamus responses to rising core

body temperature whereas the posterior hypothalamus

responds to a decrease in core body temperature.

The hypothalamic temperature control mechanism resembles

a thermostat in the way it works.

For example, when the body temperature drops due to a cold external environment,

receptors located in the skin send signals to the hypothalamic thermostat.

The hypothalamus instructs the sympathetic nervous system

to constrict blood vessels in the skin and the hormone thyroxin is

released from the thyroid gland that increases cell heat production.

Hypothalamus also initiates involuntary skeletal muscles

contraction called shivering that generates heat and

cold also stimulates voluntary behavior, such as huddling and hand rubbing and

pacing and sheltering next to a heat source and adding layers of clothing.

These processes all aid in warming the body.

Now when skin heat receptors sent say, hi, environmental condition.

That's very, very hot.

They send alert signals to the hypothalamic thermostat in the same way.

And in response, the sympathetic nervous system this time is inhibited and

this causes vasodilation of the blood vessels in the skin and

this helps dissipates the heat through the skin.

And under extreme environmental heat,

the sympathetic nervous system initiates sweating.

There are also voluntary behavior responses, such as resting in the shade,

wearing loose and light clothing, fanning, and

drinking cold fluids that all help reduce body heat and it's also being

hypothesized that high core temperatures slows the brain's activity.

And this in turn, slows general body physiological

functioning resulting in the sensation of fatigue.

So clearly, the hypothalamus is a critical temperature control mechanism.

When core body temperature drops below the safe range,

the hypothalamus sets about increasing core body temperature.

Blood vessels to the skin constrict, metabolic rate increases and

the muscles generate heat due to involuntary shivering.

And when the core body temperature becomes too hot,

the hypothalamus activates the mechanisms that promote heat loss.

Blood vessels in the skin dilate and

there is a decreased metabolic rate, and sweating occurs.

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