07-ING Marathon Training, Miami 2010: The Sweat Rate: a Crucial Measure of Dehydration During Exercise & 4 Mile Run

Today’s preparation for the 2010 ING Miami Marathon consisted of a short, easy four mile run. Nothing big, just enough to get the weekly mileage up. On another note, today as promised, we will be discussing loss of body weight during exercise or as nutritionists call it: The Sweat Rate. The sweat rate is an important indicator and gives us very important information about the body’s state of dehydration during exercise. The sweat rate also allows us to calculate optimum fluid replacement. Of course optimum fluid replacement is extremely important not only for recovery, but also to restore glycogen homeostasis and prepare us for the next bout of exercise. But firs today’s stats, followed by an explanation of  “The Sweat Rate.”

Today’s Stats: October 1, 2009

• Temperature: F 48
• Distance: 4 miles
• Time: 33:20
• Pace: Target 08:58
• Pace: Actual 08:20
• Running Goal: Easy run
• 15 minute post workout pulse: 72ppm
• Calories expanded: 680

First things first: never start an exercises session dehydrated! Its easy, just have a couple of glasses of water before hand, or if you are going on a long run, consider a carbohydrate drink. It’ll get you going.

You have heard it over and over. After hard exercise or a race it is important to replace all fluids lost, thus eliminating weight loss due to exercises. The preferred option is to have a meal up to four hours after exercises, but who wants to eat after a 13 mile run. Not many people, so the next best thing is to replace fluids with a carbohydrate drink. There are several options out there, I am using two products and I will elaborate why, and how in another post. Today, let’s just cover the basics.

What Is Dehydration: (ADA, 2009). Dehydration is a water deficit in excess of 2% to 3% in body mass! Using my run as an example: The model predicts a water loss of 4.72lb (236lb*.02%) on the lower end and 7.08lb on the upper end. The sweat rate of the 13 miler was right the middle, establishing the fact, that yes, I was dehydrated. The ideal thing would have been to avoid this dehydration by drinking fluids throughout the run, but unless in a race, it is very impractical. A runner should also take care never to consume more fluid than is indicated by the sweat rate. Doing so may cause hyponatremia, and prove potentially fatal. Hyponatremia is a result of sodium levels dropping too rapidly due to water intake. The body’s cells start to swell and eventually will burst. David Rogers, who collapsed and later died as a result of hyponatremia after completing the 2007 London Marathon is just one example of the hidden dangers of too much water (BBC News, 2007).

General Rules: Fluids: (Mitchell, 2003). Athletes should drink 2 to 3 cups of fluids for each pound of weight lost during exercises . This works well for short runs. Let’s use my long run from yesterday as an example. I lost 5.8lb during exercises. For ease of calculation let’s make it an even 6lb. Using this rule I should have drank 18 cups of fluid. That my friends is 144oz or one gallon and one pint of water! Almost impossible... But remember, it is over the course of 4 hours.

General Rules: Carbohydrates: (ADA, 2009). The optimum fuel your body runs on during endurance sports. Athletes should consume anywhere between 6 and 10 g/kg of carbohydrates per day. (2.7 to 4.5g/lb). For a runner weighing 150lb that would mean that they should consume somewhere between 405g and 675g of carbohydrates per day. I’ll cover more specific guidelines in a later post.

Post exercise regimen should consist of carbohydrate intake of 1 to 1.5 g/kg (0.5 to 0.7g/lb) of body weight up to six hours post run. Again, I’ll cover the reasoning behind this recommendation in a later post. But it has to do with optimum absorption rate of nutrients post run. There is a certain window for optimum rehydration that presents itself. Here is a post I composed recently on the subject of "Factors Influencing the Restoration of Fluid and Electrolyte Balance After Exercises in the Heat."

Next run we’ll go in the hills again for a 9 miler. We continue covering the antioxidant network.

Beste Gesundheit,

Werner

References:

ADA. (2009). Position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance. Journal of the American Dietetic Association: 109:3 pgs 509-27

BBC News. (2007). A father’s tribute to marathon son. Retrieved from http://news.bbc.co.uk/2/hi/uk_news/england/london/6587093.stm

Mitchell M. (2003). Nutrition across the lifespan. (2nd ed.). Philadelphia, Pennsylvania: Saunders

Comments

[Frank]

I would agree with most of the comments in this post, especially the 2nd paragraph. It did remind me a little bit about a similar medicine article I noticed here http://theinstituteofgoodtaste.blogspot.com/2010/01/experimental-medicine.html

[Omaha Chiropractic]

Hey nice article on a subject not often addressed. I am a runner also and treat a lot of summer sports injuries in the summer. Dehydration certainly is another problem we run into as well. Good post. Thanks!

[Robert Taylor]

“Unnecessary risks are being taken by patients seeking the liberation treatment.” says Dr. Avneesh Gupte of the CCSVI Clinic. “It has been our contention since we started doing minimally invasive venous angioplasties nearly 6 years ago that discharging patients who have had neck vein surgery on an outpatient basis is contra-indicated. We have been keeping patients hospitalized for a week to 10 days as a matter of safety and monitoring them for symptoms. Nobody who has the liberation therapy gets discharged earlier than that. During that time we do daily Doppler Ultrasounds, blood work and blood pressure monitoring among other testing. This has been the safe practice standard that we have adopted and this post-procedure monitoring over 10 days is the subject of our recent study as it relates to CCSVI for MS patients.”
Although the venous angioplasty therapy on neck veins has been done for MS patients at CCSVI Clinic only for the last 18 months it has been performed on narrow or occluded neck veins for other reasons for many years. “Where we encounter blocked neck veins resulting in a reflux of blood to the brain, we treat it as a disease,” says Gupte. “It’s not normal pathology and we have seen improved health outcomes for patients where we have relieved the condition with minimal occurrences of re-stenosis long-term. We believe that our record of safety and success is due to our post-procedure protocol because we have had to take patients back to the OR to re-treat them in that 10-day period. Otherwise some people could have run into trouble, no question.”
Calgary MS patient Maralyn Clarke died recently after being treated for CCSVI at Synergy Health Concepts of Newport Beach, California on an outpatient basis. Synergy Health Concepts discharges patients as a rule without in-clinic provisions for follow up and aftercare. Post-procedure, Mrs. Clarke was discharged, checked into a hotel, and suffered a massive bleed in the brain only hours after the procedure. Dr. Joseph Hewett of Synergy Health recently made a cross-Canada tour promoting his clinic for safe, effective treatment of CCSVI for MS patients at public forums in major Canadian cities including Calgary.
“That just couldn’t happen here, but the sooner we develop written standards and best practices for the liberation procedure and observe them in practice, the safer the MS community will be”, says Dr. Gupte. “The way it is now is just madness. Everyone seems to be taking shortcuts. We know that it is expensive to keep patients in a clinical setting over a single night much less 10 days, but it’s quite absurd to release them the same day they have the procedure. We have always believed it to be unsafe and now it has proven to be unsafe. The thing is, are Synergy Health Concepts and other clinics doing the Liberation Treatment going to be changing their aftercare methods even though they know it is unsafe to release a patient on the same day? The answer is no, even after Mrs. Clarke’s unfortunate and unnecessary death. Therefore, they are not focused on patient safety…it’s become about money only and lives are being put at risk as a result.”
Joanne Warkentin of Morden Manitoba, an MS patient who recently had both the liberation therapy and stem cell therapy at CCSVI Clinic agrees with Dr. Gupte. “Discharging patients on the same day as the procedure is ridiculous. I was in the hospital being monitored for 12 days before we flew back. People looking for a place to have the therapy must do their homework to find better options. We found CCSVI Clinic and there’s no place on earth that’s better to go for Liberation Therapy at the moment. I have given my complete medical file from CCSVI Clinic over to my Canadian physician for review.” For more information Log on to http://ccsviclinic.ca/?p=866 OR Call on toll free: 888-419-6855.

[Steskal Chiropractic Omaha, Nebraska]

I love to run, this is a very detailed article on staying hydrated. Enjoyed it, thank you!