Explore
For Enterprise
Join for Free
Log In

艺术与人文
商务
计算机科学
数据科学
信息技术
健康
数学和逻辑
个人发展
物理科学与工程
社会科学
语言学习
學位
證書

瀏覽 Coursera 的全部課程

瀏覽
搜索
企業版
登錄
免費加入

7. Immune System Responses to Exercise

Loading...

Science of Exercise

科罗拉多大学波德分校

4.8（752 個評分） | 71K 名學生已註冊

Learners who complete Science of Exercise will have an improved physiological understanding of how your body responds to exercise, and will be able to identify behaviors, choices, and environments that impact your health and training. You will explore a number of significant adjustments required by your body in order to properly respond to the physical stress of exercise, including changes in carbohydrate, fat and protein metabolism, nutritional considerations, causes of muscle soreness & fatigue, and the effectiveness and dangers of performance enhancing drugs. Active learning assessments will challenge you to apply this new knowledge via nutrition logs, heart rate monitoring, calculations of your total daily caloric expenditure and body mass index (BMI). Finally, learners will examine the scientific evidence for the health benefits of exercise including the prevention and treatment of heart disease, diabetes, cancer, obesity (weight loss), depression, and dementia.

查看授課大綱

您將學習的技能

Training, Nutrition, Fitness And Nutrition, Public Health

審閱

4.8（752 個評分）

5 stars
624 ratings
4 stars
111 ratings
3 stars
12 ratings
2 stars
2 ratings
1 star
3 ratings

MB

Mar 07, 2019

It was an excellent experience and I have learned a lot. It helped me to understand my body even better, especially since I am regularly exercising as well. I can highly recommend it.

MG

Sep 20, 2017

This course is very well designed. It provides lots of information and always scientifically proven. I would recommend it to anybody who wants to go deep into the science of exercise.

從本節課中

Physiological Systems During Exercise

In this module you will learn how a number of key physiological systems (muscular, respiratory, cardiovascular, endocrine and immune systems) are regulated during exercise to help maintain homeostasis. These adjustments are critical for exercise to continue for any significant duration. This will include: how the respiratory system adjusts during exercise to ensure proper oxygen delivery and carbon dioxide removal from active muscles; how the cardiovascular system responds to ensure adequate blood flow to various organs, including muscle, during exercise; how the endocrine system plays a major role in regulating key biochemical and physiological responses to exercise and; how exercise influences the immune system and your ability to fight infections.

1. Skeletal Muscle Structure & Function9:34

2. Respiratory System Responses to Exercise10:44

3. Cardiovascular System Responses to Exercise7:45

4. Cardiovascular System Continued9:44

5. Endocrine System Responses to Exercise8:35

6. Endocrine System Continued7:12

7. Immune System Responses to Exercise10:42

教學方

Robert Mazzeo, Ph.D.
Associate Professor

腳本

This video will examine the impact that both a single bout of exercise,

as well as regular training, have on the immune system.

The relatively new field of exercise immunology

has emerged over that past 20 years, and has generated some exciting results.

As the immune system is extremely complex, I will only address some of the key

features as it pertains to exercise and one's susceptibility to infections.

Our bodies are constantly exposed to a number of infectious agents

that could potentially make us ill.

Fortunately, for the most part, our immune system does an excellent job

of neutralizing these pathogens upon exposure.

The two major branches of the immune system are shown here.

They are innate immunity and adaptive immunity.

While exercise will affect both branches,

in the interest of time I will only focus on adaptive immunity.

Adaptive immunity will respond to a specific infectious

agent such as a flu virus.

And make immune cells specifically designed to neutralize and

kill that specific virus.

The two arms of adaptive immunity include both a humoral and cellular component.

For the purpose of this video, the humoral arm is responsible for making specific

antibodies that circulate in the blood, neutralizing infectious agents.

The cellular arm is responsible for

making t-cells that can kill cells that have all ready been infected.

Thus when we look at the responses to exercise, I will discuss the ability to

make both antibodies as well as these T killer cells.

The impact that a single bout of exercise will have on the immune system

will be very much dependent upon the exercise intensity.

A moderate bout of exercise has only a small or

marginal effect on immune function.

However, heavy intense exercise can transiently suppress

immune function up to three hours post-exercise.

Here is one of many studies demonstrating that after an intense part of exercise.

The humoral branch of adaptive immunity and specifically, antibody

production is transiently suppressed at least one hour post exercise.

This study was performed on eight well trained cyclists who exercised for

two hours at 75% of their VOt max.

Shown here is the typical response of the cellular branch

of adaptive immunity to a single bout of intense exercise.

Notice that after an intense training bout of exercise

these marathon runners demonstrated a significant reduction

in their ability to produce T-cells up to three hours after exercise.

Again, this immunosuppression was transit as T-cell production returned

to normal after six hours.

Taking together the suppression in both humoral and cellular immunity

immediately post exercise has lead to the Open Window Theory.

Basically, this theory states that for several hours after an intense

bought of exercise your immune system is transitory suppressed.

Giving any opportunistic bacterial or

virus the chance to get a foot hold leading to infection.

You may have already been exposed to these infectious agent before the bout of

exercise, but your immune system was effectively neutralizing them prior to

the intense bout of exercise.

Thus, one's susceptibility to infection is likely greater during the post

exercise recovery period.

Possible mechanisms for this transient suppression in immune function

after exercise center around the elevation of several stress hormones.

These include the adrenal hormones of cortisol, epinephrine, and

norepinephrine, which are known to be immunosuppressive.

Additionally, an increase in body temperature as occurs during exercise

may also play a role in immunosuppression.

Shown here is the cortisol and

epinephrine response from those marathon runners described earlier in this video.

You'll had a significant reduction in T-cell production

three hours after a bath of intense training.

Noticed that both cortisol and epinephrine levels remained elevated

when compared to rest for several hours into the recovery period.

So does this transient suppression and

immune function actually translate into an increase susceptibility to infection?

The answer appears to be yes.

For the weeks following a big racing competition such as a marathon,

Iron Man, or Tour de France,

the incidents of infection is two to five fold greater an athletes who completed.

When compared to individuals of similar fitness, that did not compete.

Shown here is just one of many studies that demonstrates this point.

Runners who competed in a 56-kilometer race had a two and

a half-fold increase in contracting upper respiratory tract infection,

when compared to their roommates.

As their roommates were exposed to the same possible environmental infectious

agents, this suggests that it was the bout of intense exercise that made

the runners more susceptible to infection.

Other factors that can contribute to an increased susceptibility to infection

are shown here.

I will briefly discuss the interaction between exercise and

stress at the end of this video.

People frequently ask me if they should exercise when they're sick.

Some people believe that the work out will kill any bacteria or

viruses and rid the body of toxins.

This is absolutely false.

In fact, as stated above, a single bout of exercise can suppress immune function

during the post-exercise recovery period, thus making the matter worse.

The general rule of thumb is not to exercise,

but rest if your symptoms are below the neck.

Such as muscle aches, fever, an upset stomach, and lung congestion.

If you have symptoms above the neck, such as a simple head cold,

it is generally okay to engage in light easy exercise as tolerated.

However, if you find even easy exercise makes you feel worse,

then you should stop exercising and rest until you have recovered.

As you start to feel better,

you can gradually return to your normal exercise pattern.

Now let's examine how a training can influence your baseline immune function.

The majority of studies clearly indicate that participation in regular

moderate physical activity will improve overall immunity.

Again, I will show you just one representative study of many

demonstrating this outcome.

In this study, three months of walking in previously sedentary individuals

reduced the incidence of upper respiratory track infections by approximately 50%.

Over a 15 week window of observation.

The mechanisms responsible for this training adaptation remain to be

determined, but likely involve both branches of the immune system.

While moderate training can boost immune function,

involvement in repeated high intensity training will have the opposite effect.

As I've already stated in this video,

a single bout of high intensity exercise is immunosuppressive.

Frequent engagement in these types of training sessions will chronically

suppress immune function, making the individual more susceptible to infections.

As shown here, this can result in a weakened immune system

that puts the individual at a greater risk for infection.

Even when compared to their sedentary counterparts.

The frequency of infections is a common complaint among many distance athletes.

In fact, one of the classic symptoms of overtraining in athletes is an increase

in the number of infections resulting from a chronically suppressed immune system.

Finally, I would like to discuss the interaction of stress, immune function and

regular exercise.

It is well established that repeated or

chronic stress can weaken the immune system.

And can contribute to the onset of illness and disease.

Here is just one example demonstrating that regular participation

in moderate exercise can reduce the negative effects of other life stressors

on the immune system.

When sedentary animals are exposed to a stressor,

their ability to mount an effective immune response is clearly blunted.

However, endurance trained animals when exposed to the exact same stressor,

show no reduction or impairment in immune function.

Similar findings have been found in humans.

Basically moderate exercise training can provide a degree of immune resilience, or

stress resistance, protecting you from the adverse affects of other life stressors.

In summary, a single bout of high-intensity exercise can

transiently suppress immune function allowing an opportunistic virus or

bacteria to make you ill.

Participation in regular moderate exercise can improve baseline immune function,

thereby, lowering the risk of infection.

Chronic high-intensity training and overtraining can lower immune function,

thereby increasing the rest risk of infection.

Regular moderate exercise can reduce the negative effects of other life

stressors on the immune system and, thus, your susceptibility to infections.

探索我們的目錄

免費加入並獲得個性化推薦、更新和優惠。

Coursera 致力於普及全世界最好的教育，它與全球一流大學和機構合作提供在線課程。

© 2019 Coursera Inc. 保留所有權利。

通過 App Store 下載

通過 Google Play 獲取

Coursera
關於
管理團隊
工作機會
目錄
證書
MasterTrack™ 證書
學位
企業版
政府版

社區
Learners
Partners
Developers
Beta Testers
Translators

連接
博客
Facebook
領英
Twitter
Instagram
YouTube
技術博客

更多
條款
隱私
幫助
內容訪問
媒體
聯繫我們
目錄
附屬公司