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Immune System & Exercise

Posted Jan 13 2010 12:00am
I saw it coming. After doing long workouts both Saturday and Sunday, I came home to two sick parents. That's just asking for it. Sure enough, Tuesday... I had a cold.

Hands down, took the day off. No reason to push it. Wednesday I was still a little groggy in the am but overall it was just sniffles and sneezing, no sore throat no flu-like symptoms. I go by the "neck up" theory in most cases... so I kept to my training schedule, just got a later start so I could sleep in a rest. Felt fine. Same thing Thursday. And now, Friday, I still have the sniffles, but I feel 99% better :)

It made perfect sense as to why I got the cold:

(Sorry in advance if you find this boring... however, I love this topic)

Depending on the duration and intensity of a workout, after prolonged exercise (at least 1.5 hours) certain key immune cells dramatically decrease for hours leaving you at higher susceptibility to infection. This is known as "the open window" when infection risk is high. The cells that decrease: Natural Killer Cells and T Cells, infection-fighting lymphocytes (aka a type of white blood cells). Glutamine levels, production of immunoglobins, etc can also decrease. Combined, these effects can really weaken your immune system for a while--couple hours at least with about 1.5 hours of exercise, which is nothing for any endurance athlete on the weekend. Start adding on the hours and pick up the intensity, and the weak immune system lasts even longer.

Take me for example: I worked out probably 6-7 hours on Sat & Sun, then would come home to a house with two sick parents. Recipe for disaster. Not only was my immune system suppressed, but I wasn't giving it time to fully rejuvenate before suppressing it further--and then I was interacting with the sickies, Mom & Dad.

There's another aspect to this too. When exercising you're at a higher risk of contracting an upper-respitory tract infection (URTI) due to the high volume of air you're moving. You're breathing hard... and lots of crap is going in and out. Again, take my case: On Sunday, turns out I was riding with other soon-to-be sickies, so I probably got a little of their infectious germs when we were riding close and blowing our snot rockets ;)

Now, on the flip side, besides the risk of URTI, your immune system actually strengthens during a workout (i.e. WBCs increase), and certain cells will remain increased after as well.

BUT, for endurance athletes working out 75-90 min or longer on a regular basis, be careful. Chronic endurance training does suppress the immune system, well, chronically. Why? Not enough recovery time between bouts, increased cortisol (stress hormone & immunosuppressor), low glutamine, etc. Also, if your plasma volume increases (often an effect with endurance training for O2 carrying, better sweating, etc) this causes a lower concentration of immune cells like leukocytes. Plus, if you have poor nutrition you might as well throw in the towel.

An article on the same topic was recently posted on Active.com, and I think it's important to highlight one section especially.

"Regular runs can bolster your immune system." Well that goes against what I just said about chronic training = depressed immune system, right? The key to that statement is: the runs have to be 45 minutes or less and only at moderate intensities. Most long-distance triathletes are training more than 45 min in most of their sessions and are going at pretty high intensities vs. just moderate.

The article then goes on to talk about the "open window" theory, in their example, after running a marathon. Really would make you think twice about flying home on a plane the day after your big race. Ewwww.

Lastly, it talks about "sweating out a cold" and how that's not possible. I was laughing when I saw that because on Wednesday I commented on a sick friend's FB post saying "I sweated out my cold." I don't actually believe I did that! In my case, I knew I wasn't too sick to work out (neck-up theory), so some exercise wasn't really going to do much harm. And I was right--it's Friday, I feel totally fine and I didn't miss out on much training. In fact, I was able to "clear everything out" pretty well, if ya know what I mean.

So here's a little advice on the best things you can do to save yourself from an annoying cold:
-High *good* CHO diet, including CHO during the workout (*good* CHOs, so not chips and crappy stuff haha)
-Plenty of antioxidants, food is better than supplements
-Possible benefits with Glutamine supplementation. "The Glut" is used by leukocytes for energy aka fuel for immune system (I'll be starting this up again)
-Avoid contact with SICK people (oops!)
-All the regular hygiene stuff, OCD style if you must


Take home message: You're most vulnerable for picking up a sickness after a long, hard workout of at least 75-90 min. So quarantine yourself and hoard all the healthy foods!


(Wonder how many people made it to reading this far, hmmmm)
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