OK, so here I am, feeling good, feeling strong.  Back to a decent weekly mileage after 3 months down and wham!  Yet another hideous, head cold - my second in about thirty days.  I really have no patience for this. The good news is that if the average adult has 2-3 upper respiratory illness each year, then I am at least 2/3 of the way there for 2009!

Typically, I ignore head colds and run anyway, but this cold - man it was a killer, just like the last one.  Not since my days as an unhealthy smoker have I experienced such constant sickness and I have to ask myself whether not being able to run for those several months compromised my immune system.

Research has shown a link between exercise and a strong immune system, which responds with real physiological changes when we get out and move.  During exercise immune cells circulate through the body more quickly and are better able to kill bacteria and viruses. After exercise ends, the immune system returns to normal within a few hours, but consistent, regular exercise seems to make these changes more long-lasting.

Dr. David Nieman, Director of the Human Performance Laboratory at Appalachian State University found that when moderate exercise is repeated on a near-daily basis there is a cumulative effect that leads to a long-term immune response. Running strengthens lymphocytes and neutrophils - immune cells that protect us from bacteria and viruses that cause illness and infection. Neiman's research showed that those who walk at 70-75 percent of their VO2 Max for 40 minutes per day had half as many sick days due to colds or sore throats as those who don't exercise.  However, there is a catch.

Most data cite immune boosts after 30 to 75 minutes of moderate activity. Runners doing longer or more intense workouts  don't usually see this benefit. In fact, a large body of research, mostly from Appalachian State indicates that a strenuous workout or prolonged periods of heavy training can have the opposite effect.  According to Neiman, "When you're running for 90 minutes or longer, there's a temporary downturn in immunity," Around the 90-minute mark, he says, carbohydrate stores drop, causing a spike in two key hormones, cortisol and epinephrine. This, in turn, inhibits those neutrophils and lymphocytes, leaving you vulnerable to nasty bugs.

So, how to protect ourselves?  Viruses have a greater chance to get a foothold during an "open window" of impaired immunity--three to 72 hours after a workout. One way to prevent this dip is to drink carbohydrate-rich beverages before, during, and after your run.

Nieman found that consuming sports drinks keeps carbohydrate stores high, slowing the rise of stress hormones and offsetting negative immune responses. On the day of a workout that exceeds 90 minutes, he recommends drinking 16 ounces of a beverage containing 60 grams of carbohydrate (the amount in most sports drinks) 30 minutes before you start. During the run, drink an additional 16 ounces every 30 minutes. Then, after your workout, drink another 16 ounces. Nieman says fluids are the fastest delivery system for carbs, so if you substitute your postrun drink with a banana or bagel, it's a good idea to wash it down with water.

After your workout, be extra diligent about washing your hands frequently and avoid crowded places.  (Hey, this is like having a newborn!) Neiman's additional sage advice is the one we all know.  Avoid increasing both the intensity and volume of your training at the same time.  Raise your mileage, then hold it at that level for a week or two before adding in speed workouts.

In case you're wondering about supplements, according to Neiman,  loading up on supplements doesn't prevent these illnesses.  And here's a direct hand slap to mothers everywhere: bundling up against the cold or rushing to get out of your damp workout gear isn't likely to keep you from getting a cold or the flu either.  According to Briam McFarrin, a Univesity of Houston exercise physiologist, "The idea that because you're cold you're going to get sick is an old wives tale." (Personally, I've always hated that expresion, but there you have it.)

So, it sounds like it's entirely possible that my little hiatus from running did a lot more damage than even I thought it did.  I am going to work like the dickens to make sure it doesn't happen again.  What's more, I now have yet another reason to love running; eat what I want AND have a strong immune system!

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Tags: running while sick, immune system, running prevents illness, immunity and running

You are on the right track -- physically, mentally and emotionally Posted by: bennettc on Feb 10, 2009 at 07:42 PM

You are so right. After I got the "all clear" several weeks ago from my physical therapist to do a long training run over the weekend (11 miles), I was really excited. Come that Sunday, I began experiencing very severe pain around mile 6 and had to completely stop running. This of course was REALLY devastating to me. And the worst thing is the psychological effect - the feeling of being defeated by injury. After that weekend, I decided to go slow and steady with a VERY gradual build on the mileage. Doing it this way, I am experiencing little to no pain. I am now back up to about 6.5 miles/run, and I can even do a little tempo work. Even though its a far cry from where I was pre-injury, the completion of these longer runs not only feels great physically, but also helps rebuild confidence in my ability to heal. Posted by: bmoore on Feb 10, 2009 at 12:07 PM

You are correct. Starting back on increased mileage after a three month hiatus from running has resulted in your recurring head colds. After a long layoff, runners are all raring to go, ready to hit the roads (or trails). However, you cannot pick up where you left off prior to the injury. All of your systems (not just musculoskeletal) need to get used to training again. What to do? First, recover completely from your cold. Then, resume running at one-third to one-half of your weekly mileage prior to injury, with no intensity work. Stay at this level for 2 weeks. If you are feeling strong, that means your body has adapted to the new workload and you can increase mileage gradually (over the course of several weeks) until you reach your pre-injury level. If you are not feeling strong after two weeks, reduce your mileage i.e. "Do not pass go; do not collect $200". I realize that this may be very frustrating for you. Gaining a better understanding of how your body reacts is a continual process for runners. Your body will tell you when it is ready to move forward. Be patient. Listen to your body. Take the ncessary time to recover completely. You'll be back running soon. I'm cheering for you! Posted by: bennettc on Feb 10, 2009 at 05:44 AM

You know, I have been keeping a log ever since I started running. At first it was simply so that I could admire my accomplishments, but gradually, it became an essential part of coming to understand my body, my monthly cycles (and how my running was effected) and also in helping me keep track of the way my dietary and lifestyle habits effected my health. I wonder, do you think that starting back on increased mileage after my injury layoff has caused this constant bout with head colds? Posted by: bmoore on Feb 09, 2009 at 08:23 PM

Wishing you a speedy recovery, Beth. My own experience substantiates Dr. Neiman's conclusion that running longer than 90 minutes does temporarily suppress the immune system. After my last training period which had lasted 20 weeks, I reviewed my running log and noticed that on five occasions, I had written that I felt like I was coming down with a cold. Every such entry was written on a Tuesday, following a Sunday long run or race. Hardly a coincidence! By taking a few days off each time, I avoided developing a cold and having to suffer through a longer layoff from training. I concluded that I needed to incorporate more rest into my training. Yet another reason to keep a running log! Posted by: bennettc on Feb 09, 2009 at 07:07 PM