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Author Topic: Can physical exertion alter immunity?  (Read 3312 times)

Offline becharab

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Can physical exertion alter immunity?
« on: 09/07/2009 04:30:02 »
Bishara Bardawil asked the Naked Scientists:
   Hello from Beirut, Lebanon!

I regularly listen to the newbielink:http://www.thenakedscientists.com/HTML/podcasts/ [nonactive] which I enjoy tremendously!

I exercise on the treadmill from time to time. However, whenever I push my limits, invariably I come down with the flu (sore throat, high fever) a few days later.

My question is the following: Is there a relationship between physical exertion and lower immunity?

Thank you Naked Scientists

What do you think?


 

Offline JnA

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Can physical exertion alter immunity?
« Reply #1 on: 09/07/2009 06:27:26 »
There's a line. Moderate exercise is good. It is thought that moderate exercise helps to blast out bacteria from the lungs and help get rid of carcinogens by the increase urine and sweat. Also that raising the heart rate helps white blood cells pump around the body faster thereby detecting and fighting illness further. And a temporary rise in body temp may hinder the growth of bacteria.

however

overexertion might decrease the amount of WBC and increase stress levels.. which is bad. But, I believe, the levels need to be somewhat marathon like to reach this paradox in exercises health benefits.

 now, perhaps your 'pushing you limits' really is creating these negative health effects, or maybe it's juts your body going through the 'flushing' process.. or maybe the others at your gym aren't great at wiping down the surfaces and you are just getting transferred bacteria from the equipment.


remember moderate exercise - good, marathon running - bad
 

Offline Pwee

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Can physical exertion alter immunity?
« Reply #2 on: 13/07/2009 10:15:37 »
Hi!

I think I have an answer for you (in a little bit more detail).

As JnA have said it before, overexertion can cause immune functions to go down a bit.
This is moderated by several factors. One of this is that immune cells use the same energy sources as muscle cells. When you exercise really hard, you burn the accessible energy in your system, muscle eat up all the glycogene and your immune cells will have less energy to use.
There are some really complicated hormone processes going on constantly in our body that regulate immune functions too. During intense exercise, you flood your system with adrenalin. Adrenalin (Epinephrine) usually functions as an upper for your immune system, but at the same time, stress hormones like Glucocorticoids start to be produced too, which is a downer for your immune cells. Unfortunately, adrenalin is used in bursts, it cant remain in your system for too long, on the other hand Glucocorticoids (like cortisol) can be produced and go on to act in your system for much longer. So in a short time (and when you stop the exercise), Adrenalin's effects start to ware off, and the effect of the main stress hormone, cortisol stays in effect and starts to down-regulate the immune system.

So you are not alone with your experience that you get sick after too extreme exercise. There is a good theory that tries to explain this. It's called the "open window hypothesis": There is a paradox that people who do sports regularly have more fit and better functioning immune system overall then others, but sometime they experience the same thing as you do. So the scientists say that when you do an exercise and the effect of the adrenalin and the level of excess energy in the system goes down, the immune function goes down gradually. This effect is especially pronounced when you stop the exercise as then you really don't produce any upper hormones but the Glucocorticoids still has an effect on your immune system. So there is an "open window" for germs to try to invade your othervise flawless defences. Of course your immune system slowly regenerates (in some hours depending on the level of overexertion you put yourself through).

There is not much that you can do, I think it helps if you try not to stop the exercise abruptly, not to go out to the cold immediately after the exercise, have a good hygiene, but I think you allready know these things. The main thing is not to strain yourself to the extreme limits.
If you stay inside your limits, doing sports makes you much more resilient to infections overall, so it is worth it.

Also I think you can find tons of material of this on the internet.
 

Offline becharab

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Can physical exertion alter immunity?
« Reply #3 on: 17/07/2009 14:08:30 »
Thank you JnA and Pwee! I found your answers to be very helpful and informative...

I'll turn down my workout intensity a couple of notches then and see what happens.

PS: I found it surprisingly difficult to find relevant material on the internet  :-\

 

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Can physical exertion alter immunity?
« Reply #3 on: 17/07/2009 14:08:30 »

 

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