Wednesday, January 13, 2010

Immune System & Exercise

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, 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)


  1. Great info and timely post as I got sick Tuesday, too! But with a stomach bug :x Wonder how this lines up with what you've posted here? Hope you feel better soon. Rest up this weekend!

  2. Thanks Toby,

    Going with the whole "neck-up" theory, I definitely wouldn't workout if you have a stomach bug. That would just be awful and probably delay your recovery.

    Wonder if you picked up the bug when your immune system was down post-workout?

  3. Definitely a timely post. I just spent some time this week researching the same thing because I came down with the stupid seasonal sickness and I couldn't shake it in my normal time frame. Good info there and as boring as the topic may be, it's a great read. thanks

  4. Excellent information Tawnee. I was wondering if the temperature has a place in this theory?

  5. Great info! I worked out hard for the last two weeks and guess what? ended up sick. It feels like I'm being choked from the inside, and have had to take three days off :( bah! Hope my immune system kicks back in full force!

  6. Ron,

    Good question. While I don't know the answer of whether there's a direct link b/w getting sick and working out in the cold, for example, I do know exercising in cold can cause stress hormones such as cortisol to increase more than normal. Plus, if you're having to produce more heat to stay warm (i.e. shivering), you're body is working harder; in a way that's like working out at a higher intensity without even trying. Those stressors may result in greater immunosuppression post-exercise.

  7. I am one of the people that didn't read the whole thing. I'm sure that doesn't surprise you though (and I suspect that I would know most/all of what you posted anyways).

    FWIW: I don't think those of us training in colder temps are more likely to get sick - UNLESS we act like dumbasses and do things like wear shorts when it's freezing out ;)

  8. I haven't been sick in 10 months. I've had 1 head cold in that time. 10 months ago I started taking glutamine daily, and also after long/hard workouts. And I take all sorts of stuff (vitamin c, echinacea, more glutamine when I travel (as well as carry my own tea bags so I can have hot tea on the freezing cold airplanes). At the first sign of a cold or anything I drink kombucha tea. I don't know if one thing is working or not, but I haven't missed a day of training due to being sick. Hopefully I can make it 8 more weeks so it will be year.

  9. great stuff, will you marry me? :)

    it's sad when no one around you understands this stuff and if you try to live healthy those people get angry at you and only try to poison you!

  10. You'll be healthy by Carlsbad - good timing :)