Doc’s Talk 04-01-2012

Dr. Scaff gave a few additional pointers on running shoes, and then spoke to the group on some of the dangers associated with running and the body mechanics of warming up, core temperature, dehydration, fluid loss and heat stroke, high blood pressure, salt in your diet, drinking water, and urination.

Additional Notes on Purchasing Running Shoes
To last week’s talk on running shoes, Dr. Scaff added:

  1. The best time to pick your shoes is in the afternoon after a 1 hour run.
  2. Get shoes in which you have a 1 to 1½ finger width of space between your longest toe (usually the first or second toe) and the toe box of the shoe.

With the variable ways of lacing [see page 128 of Your First Marathon – The Last Word In Long Distance Running, by Jack H. Scaff Jr., M.D., F.A.C.S.M], you can always make shoes fit smaller, but cannot make them bigger.  Buy shoes that are one size bigger than your foot measures after a 1 hour walk or run; Dr. Scaff promises, you will grow into them.


The Mechanics of Running …and Some Dangers Associated with Running

Warm Up
Before a run, people are correct in saying, “I gotta warm up.”  At 101° Fahrenheit enzymes burn your body’s fuel with the highest efficiency, and the oils in your cartilage and knees are most fluid (like warming up your car in cold weather to let the oils thin out). 

Warming up is much more important than stretching, …which actually isn’t very good for running.  If you like to stretch, fine, but be careful.  Dr. Scaff has several studies that show runners who stretch have a higher percentage of injuries (stretching may be okay in other sports).  The lead runners in the Honolulu Marathon have told Dr. Scaff they don’t stretch prior to a run, they warm up by running back and forth (they only stretch when the cameras are around because that’s what people expect to see!).

Core Temperature
Your body is just like an internal combustion engine:  You have a motor, cylinders (legs), you have a carburetor which distributes the oxygen (lungs), you have a fuel system (heart and vessels), and you burn fossil fuel …or what would be fossil fuel if it stayed underground long enough (i.e. you eat animal fats and vegetative matter).

Heat is a byproduct of work.  As you start exercising, your core temperature goes up.  At rest, most of us have a core temperature of 98.6° Fahrenheit (37° Centigrade).  As you start exercising, core temperature starts to increase.   At the end of an hour it is perfectly normal to have a core temperature of 101° (Rectal, not mouth temperature.  Breathing through your mouth lowers mouth temperature).  That is the optimal temperature for running.

After you stop exercising your temperature (called basal metabolic rate) remains at 101° and will not come back down for 4 – 5 hours because you’ve switched into fat metabolism.  At that temperature your body can continue to burn fat even after you stop running.  This is why some people recognize that they are losing weight faster than they thought they could even though they are not running enough to burn off that many calories.

The byproduct of heat is sweat.  If you do not replenish your fluids while running you can become dehydrated.  If you become dehydrated your core temperature starts to increase, …and you run the risk ofenvironmental heat illness and heat stroke.

After 10 minutes of running (if you are a 10-minute runner) urine production ceases and the skin begins to take up the function of the kidneys via the production of sweat.  If you’ve ever tasted your skin after a long run it is salty because of all the sodium you have sweated through your skin.

Doctors treating high blood pressure and the American Heart Association say you should eat a low-sodium diet, …but if runners take that advice it will kill them!!  The reason is that when you run and sweat you’ve got to excrete something, and because the skin does not work as well as the kidneys, if you don’t have enough sodium you will start excreting potassium or magnesium, or calcium.

High Blood Pressure & Salt
Dr. Scaff recommends
everyone, especially those with high blood pressure, or those whose doctors think they have high blood pressure, or are on diuretics, read Chapter 22 “Hypertension – More Than You Ever Wanted To Know About High Blood Pressure,” of his book Your First Marathon – The Last Word In Long Distance Running.

It’s a long chapter, it’s technical, but it is an important chapter, and contains some very good data.

Dr. Scaff wrote that chapter a couple of years ago, and since then The New England Journal of Medicine and others have all come out saying exactly the same thing.   Essentially, while many books still say you should eat a 2-gram salt diet, you don’t need to be afraid of salt.  Dr. Scaff is not afraid of salt, and will eat to eat shoyu, anchovies, etc.  In fact, the Honolulu Marathon Clinic recommends eating pretzels, which have carbohydrates and salt, during your run.  The Honolulu Marathon Clinic introduced “power pretzels” to the running community about 5 years ago, and now other marathons across the nation (the Chicago Marathon, the Portland Marathon, the New York Marathon) recommend taking pretzels on your run.

Dr. Scaff says pretzels are better than power gels.  He’s not against power gels, but they are just an expensive way of getting the sugar.

How much water should you drink?
Roughly ten ounces every 20 minutes.
When you get up in the morning you are usually 1 – 2 pounds lighter.  That is due to insensible water loss.  Even in your air-conditioned office you’re losing water.  Learning to drink water or a beverage is a full time job because you’ve got to replace your insensible water loss, and then your sensible water loss (sweat).

Fluid Loss and Heat Stroke
When you finish your run you should weigh yourself on a scale.  You may be down as much as 4 pounds or so, which is a lot of weight.  You’d have to fill up gallon jars to hold 4 pounds of fluid.

Dr. Scaff brings this to your attention because when you’ve lost 5 – 10% of your body weight, your core temperature starts to increase, and when it reaches105 – 106 degrees Fahrenheit, environmental heat illness followed by heat stroke occursUntreatedheat stroke is 85% fatal.

A beginning runner can’t get heat stroke because they run and they puke.

What happens if you take over 6 hours in the marathon?  You’ll probably urinate along the way.  Heat injury occurs in the faster runners, the rest of us are so slow we’re healing faster than we’re running [joke: laughter, applause].  It is rare to see heat exhaustion in a 10-hour marathoner.  So even though many are older and may have more cardiovascular risk factors, Dr. Scaff doesn’t worry as much about them as he does the weekend athletes and those in their middle years who are “bulletproof” and “can do anything”.

Urination, Thirst, and Dehydration
The bottom line is, you should urinate within 4 hours of your run, and your urine should be colorless once per day, meaning when you use the toilet bowl a person following after you can’t tell anyone has been there.  Beer drinkers can do that very easily, but for those of us who drink regular water or soda it is very hard to do.  If you take vitamins your urine is going to be yellow regardless.

Can you over-drink water?  Yes, …but if you follow these simple rules you won’t:

  1. Colorless urine once per day, and 
  2. Urinate within 4 hours of your run.  

Simple as that.

If you wait until you’re thirsty, that’s the end-point.  Thirst is a lousy end-point.  Even though you may not be thirsty right now, you may, in fact, be dehydrated.  So pay attention to the rules.

Fuel for Thought
Even if you don’t need water on a 1-hour run, you are now training your body for everything.  Just as you’re training your feet for a 26-mile run, you’re training your stomach too, so you’ll be able to drink water and eat pretzels or whatever you like when doing a marathon.

For those who do not have high blood pressure, just stop at all the water stops.

The bottom line is, pay attention and listen to your mother and your father:  Mother Nature and Father Time.  They’ll take care of you.

For more information on heat stroke and fluid replacement, refer to Chapter 9 “Ninth Month”, in Your First Marathon – The Last Word In Long Distance Running, by Jack H. Scaff Jr., M.D., F.A.C.S.M., available for purchase at the Honolulu Marathon Clinic on Sundays and online at:

For some good reading on nutrition, Dr. Scaff recommends everyone check out the daily postings on Dr. Alan Titchenal’s “Got Nutrients?” web site:

Here is a recent posting:

March 26, 2012
Gatorade for athletes and Pedialyte for infants and children are both designed to provide water, carbohydrate, and electrolytes. Although both beverages are essentially properly diluted Kool-Aid with a pinch of salt (sodium and potassium), Gatorade provides more carbohydrate to meet the energy demands of exercise. Pedialyte has a higher electrolyte content with a primary focus on hydration of sedentary infants and children.

Consumer Link
Athletes Go Gaga For Pedialyte

Research Link
JPEN J Parenter Enteral Nutr. 2006 Sep-Oct;30(5):433-9.