Is too much exercise bad for your immune system?

For years and years HCP's have been telling you that "moderate" amounts of exercise are good for you and your immune system especially during the winter months to prevent colds, flu, respiratory infections, etc. And, I am not going to tell you any different, BUT I am going to give you an explanation as to why exercise can boost your immune system and how much exercise can actually put a strain on your immune system.  Actually, one study showed that people who didn't exercise and started 12 weeks of moderate exercise had over a 50% drop in sick days over the next year!!

Who can benefit?
The best part is that everyone can!  Even with chronic diseases or autoimmune diseases, you can find YOUR level of moderate exercise and it will only benefit your body, your general health, and support a healthy immune system.  For example, if you are bed bound, there are arm exercises, rolling in bed, leg lifts...a form of exercise depends on what you are used to.  So, everyone should be getting some form of moderate exercise, there is NO excuse!

How does it support your immune system?
So, the immune system is a whole network that has been created by our body to protect it from invasions from viruses and bacteria using various different hormones, chemicals, and cells to attack, as well as to remember, the viruses in the future to prevent further attacks and hone your bodies response.  In an effort to not get too deep into cellular anatomy and physiology, I just want to explain that some of the cells that respond are called cytokines (of which there are many different types).  Some of the cytokines release a signal to your white blood cells (the ones that increase in number to attack when their is an invader present in your system- your number will be elevated if you have a cold, for example, and get your blood drawn at your HCP, but it will drop back down to a "normal" level when you aren't sick) that there is an invader, then there is an inflammatory response, and the white blood cells know to go in for the kill.  So, why am I telling you this?  Well, with a moderate amount of exercise, the cytokines are produced and released in moderate amounts, so your immune system is being challenged a little bit every time you exercise, and it strengthens your immune system because it is constantly working.

Why is too much bad?
If you overtrain, or exercise too much, you can cause damage to some of the muscles, or various different cells in your body, and it can stress your body.  When your body feels stressed, overexerted, or over taxed your immune system is actually decreased because your body is working so hard to recover your muscles from training, that your immune responses can be lowered due to a release of higher cortisol levels.  Cortisol is a natural hormone that is released from the adrenal gland that helps to regulate metabolism, the immune system, inflammatory responses, as well as having other functions; it is basically your "stress" hormone and the one that jazzes you up during your "fight or flight" response.  The problem with is being constantly elevated, is that your body is never truly relaxed (which can occur in our modern way of living where everyone is running around, working tons and constantly stressed even when we don't realize it) and this can lead to slower immune system responses and slower healing by the body due to the way that cortisol makes your body react.   So, too much exercise can depress the cytokine release, and make your body slower to react to minor pathogens (viruses/bacteria) that may be trying to invade your body.

What is considered Moderate exercise?
Usually it is defined as 20-30 minutes of exercise 5 days a week.  For me, that is not enough because my baseline is much more than that, so that is a great guideline but it needs to be based on your level of exercise specifically.  So, I would tell you that "moderate" really means what you feel comfortable with in exercise, can get through without feeling tortured and on a scale of 1-10 (one being barely any effort and 10 being extreme effort), it would be a level 4-6; where you are comfortable and can even talk during the exercise (not a lot mind you, but you aren't struggling for breath).  Moderate exercise can vary with days that are a 6-8(a little harder) and days that are a 4-5 (a little easier) but try to stay around that range for cardio.  You can push harder twice a week, for better results, but if you are happy with how in shape you are, try to keep it relatively even.  As far as lifting, you definitely want to add some muscle strength on top of your cardio, but again, don't stress yourself out (i.e. you can barely lift your arms afterwards), but push yourself daily to the point that you know you have worked out and feel stronger.

What is too much?
Pushing yourself to run at a super fast pace and for a long distance when every step you feel like to want to stop...that is too much.  You need to listen to your body (and non-runners, will probably say, "my body says that every time I run" I'm talking to those who are runners baseline).  Or if you are working out on the scale of an 8-10 every day, that is too much!!  You can go 8-10 once or twice a week, but really no more than that. If you feel strains in your muscles or muscle tears, you need to take a break and your body will let you know.  I totally understand the feeling of wanting to push your body to the limits EVERY time you work out, I have done that in the past, and I looked fantastic, but it isn't sustainable over time, because as you overtrain, your body loses interest in wanting to work out and it gets harder and harder to push yourself to do so.

For my avid exercising readers, just listen to your body; it will tell you when you are overtraining!  Sometimes every step feels so horrible you just can't exercise- then STOP,  just lift weights, or take a break and catch up on some missed TV shows and DON"T FEEL GUILTY about it!! Just go back to your normal routine the next day, Nurses orders :) You really need to look at exercise as everything else, do it in moderation, and it will be sustainable over your whole life, not something that you stop and start.

For those of you who don't exercise, I hope this inspires you to park farther away from the store and get a walk, skip the elevator and take the stairs, and grab a friend (bundle up) and go for a wintery walk and a cup of coffee/tea!  Try to get out there and get that heart pumping to stimulate your immune system!!  It actually is good for you, gets you out, and can help you also beat the winter blues (check my blog tomorrow!)

Yours in Good Health
B