Sunday, August 5, 2012

How To Maximize The Health Benefits From Walking

Benefits of walking depend on how you do it. 
I am a big fan of walking.  It is a low impact exercise that almost anyone can do.  It requires little more than comfortable shoes. And, it gets you out of the house and into the fresh air.  What more could you want?

There is a walking craze going around.  With obesity at alarming levels, the airwaves and bookstores are filled with doctors and fitness experts telling us that we need to be more active.  They are right, too. We Americans take the car to drive a block to the convenience store for milk!  Don't tell me you haven't done it, or something equally as silly.  We all have.  So, we are advised to get off our fat butts and walk.  Yeah, that oughta do it.

Walking, however, is not the same for everyone.  Some folks walk fast, some walk slow, and the older you are, the slower you probably walk.  So, as far as health benefits are concerned, is all walking the same?

Short answer: No, all walking is not the same.  The benefits one gets from walking are not dependent on just moving our legs.  The benefits are derived by increasing our heart rate, and a casual stroll probably ain't gonna do that. Don't get me wrong.   If slow, casual walking is the only exercise you want to do or are capable of doing, then please continue with it.  Slow walking certainly is better than not walking, and it does have some minor health benefits.  However, casual walking, no matter how much you do, may not meet the minimum levels for exercise recommended by health professionals.

Here is why I say that.  Just about everybody, from the National Institutes for Health (NIH) to the American Heart Association (AHA) advise about 150 minutes of moderate exercise or 75 minutes of vigorous exercise each week.  Moderate exercise, however, is not taking a stroll.  It is defined as exercise at a level that elevates the heart rate and breathing rate, and may make you sweat.  Therefore, if you are walking, you probably need to be walking briskly to get to this level. This makes it an aerobic exercise!  Aerobic exercise is the minimum you need to do to achieve and maintain good health.

Maximum Heart Rate

How do you know if you're walking at the moderate or aerobic level?  Well, the best way to find out is to monitor your heart rate.  If you can increase your heart rate to 50% to 60% of your maximum heart rate (MHR), then you are in the minimally beneficial zone.  If you are less than "fit", this level may be achieved by walking, probably at a quick pace.  As you become more fit, however, this may no longer do it for you.  Jogging or biking (even stationary) may be needed to get your heart rate up high enough to do you some real good.

Warning here: Please read all of this.  Yes, there is some simple math, but it is absolutely essential that you understand it if you are to achieve even a minimal level of fitness from walking.  That is because 50% MHR is not half of your MHR, despite a number of web sites that say it is!  This is a common misconception.  That number is calculated differently than you might expect, and is explained below.

What is meant by maximum heart rate (MHR)?  Well, it is simply the maximum number of beats your heart is capable of producing without going into fibrillation.  This value decreases with age.  If you have had a recent stress test, your doctor may be able to tell you what that number is.  However, if you haven't, you could go out and really push yourself by running far and fast (not advised unless you are in shape) and taking your pulse.  There are also some formulas that have been published that can estimate your MHR.

Do a Google search for MHR formulas and you will find the formula below, which is one that is most commonly used.  Even the Livestrong website uses it.  This formula, like others, uses your age to arrive at an estimate, based on "studies" correlating age to MHR:

220 - age = MHR

I don't like this formula.  If I were to use that formula, my MHR would be 220 - 58 = 162.  That's not even in the ballpark for my actual MHR!  While running up hills wearing my heart monitor, I have reached 181 bpm, and probably could have gone a bit higher.  So, either I have the heart of a 39 year old, or the formula is wrong.  What does that tell you?  These formulas aren't always reliable.

Heart Rate Zones

There are 5 heart rate "zones" that are generally recognized by trainers and doctors. Visit this web site for more information:

However, be aware that the values for the heart rate zones are not simply found by, say, multiplying your MHR by the corresponding fraction (Livestrong and other web sites (mis)calculate it this way, but that is incorrect because you could actually calculate an aerobic heart rate below your resting rate, which is not realistically possible).  In other words, 50% MHR is not half of your MHR.  Instead, 50% MHR really means your heart rate when working at 50% of capacity. Wow, that is confusing.

You must know one other piece of information to make the simple calculations for your heart rate zones.  You need to know your resting heart rate (RHR).  That is easy to do.  Just take your pulse while resting. My BP machine also finds this value.  Now, here is how you find your heart rate for each zone.  

Let's say you want to know your value for 50% MHR, the minimum you need to sustain during aerobic exercise.  Use this formula:

  • Subtract your RHR from your MHR, thus giving you your working heart rate (WHR). 
  • Calculate 50% of the WHR by multiplying the WHR by 0.5,  giving you a new value we'll call "Z". 
  • Now add "Z" to your RHR to give you your final value.
For me, it works like this (my RHR is 68 bpm):

181 bpm - 68 bpm = 113 bpm (this is my WHR)
113 bpm x 0.5 = 56.5 bpm
68 bpm + 56.5 bpm = 124.5 bpm (my 50% MHR value)

So, my 50% MHR is 125 bpm.  Note that this is a far cry from half of my MHR, which would have been about 90 bpm had I used the erroneous method published all over the web.  

Walking at 50% MHR

Okay. Back to walking. I had a point to make.

I had a leg injury last spring and tried walking instead of running.  I was in pretty good shape at that time, able to run five miles with effort.  When I strapped on my heart rate monitor to go walking, I found that I could not walk fast enough to get my heart rate up to an aerobic level.  My heart rate averaged only 108 bpm.  I walked like an Olympic speed walker for 3 miles (5 kilometers) and never reached even the lowest aerobic level.  Here is my heart rate graph for that effort, keeping in mind that 50% MHR for me is 125 bpm:

My heart rate while speed walking for 5 kilometers.

So, that is why I have stayed with running. I don't run fast, but even an easy jog gets my heart rate up enough to maximize my health benefits. When I run, I try to stay in the range of 75-80% MHR, which is considered the most beneficial range for vigorous aerobic (fat burning) exercise.


So, here are my recommendations:
  • Get a stress test before you begin a strenuous exercise program.  
  • Find your MHR.  Then calculate your minimum aerobic-level heart rate (50% of MHR).
  • Get a heart rate monitor (there are some inexpensive ones at Best Buy).  If not, at least take your pulse off and on during your walk.  Some treadmills also have heart rate monitors built into the handles.
  • When you walk, try to get up into the aerobic zone and stay there, if you can.  Walking uphill will help.
  • If you cannot walk aerobically, you may need to consider another exercise.
  • Two and a half hours per week should be your minimum if you want to exercise by walking.  You can probably cut that time in half if you jog or run.  
Remember, aerobic exercise burns fat, strengthens your cardiovascular system, and the sweat makes your skin nice and soft!  Don't forget the sunscreen!

See you on the walking path!

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