May 22, 2008

Drinking Problem

A common concern during a marathon is knowing how much to drink. A general recommendation during exercise is to drink 8-12 ounces every 20-30 minutes. However, the fear of dehydration during prolonged exercise, such as a marathon, has led some to recommend marathon runners to drink as much as they can tolerate. Add to this the notion that runners shouldn't wait until they are thirsty to drink because the brain's thirst mechanism lags behind the body's need to water and you have some marathon runners drinking to the point they become hypontremic (low blood sodium) which can cause all sorts or problems including death (see New England Journal of Medicine, April 2005.)

The increase in the number of hyponatremia in marathon runners over the past years have caused an reevaluation of the drinking recommendations for marathon runners. Dr. Tim Noakes was one of the first to recommend marathon runners to drink fluids ad libitum or as they felt the need to drink. But, wouldn't this led to dangerously high body temperatures? Noakes argues that other factors such as running speed, body size, and environmental factors play a larger role in causing hyperthermia. (see Clinical Journal of Sports Medicine, September, 2003.)

(My heart rates during the 2002 Wash. D.C. marathon. The increase at the end was not due to me running faster but a compensatory response to being dehydrated and having less blood volume to pump. Yes, the miles are off. It wasn't a 28 mile marathon.)

The American College of Sports Medicine agrees. They recommend drinking enough during a marathon to prevent losing more than 2% body weight through dehydration and this can likely be accomplished by drinking, according to thirst, 400 ml (13.5 oz) to 800 ml (17 oz) every hour. (see Medicine and Science in Sport and Exercise, Feb. 2007).

Just like the recommendation to drink 8 glasses of water a day is a myth (see British Medical Journal, December, 2007), so is drinking more than your thirst dictates during a marathon.

May 8, 2008

Risks of marathon running

Last week a 55-year old man collapsed at mile 10 of the Flying Pig Marathon. Luckily, a group of emergency medical technicians were running just behind him and immediately administered CPR. Bobby Edwards, who had completed the previous 9 Flying PIg marathons, also had to be shocked three times with a defibrillator before being taken to a hospital where he's expected to make a full recovery. So, just how risky is running a marathon? A recent study by Redelmeier in the British Journal of Medicine found 26 deaths out of 3,292,268 runners from major marathons held in the United States. Earlier data collected by Maron and Roberts found a similar risk of 1.1 deaths per 100,000 runners from 15,239 runners of the Twin Cities marathon and the Marine Corp Marathon between 1976 to 2004. Interestingly, Maron and Roberts found the relative number of deaths decreased over those year despite an increase in the number of marathon runners. The decrease was in large part due to "availability of life support and timely defibrillation". Plus, the benefits of regular exercise required to run a marathon likely out weigh any risk. 

1. Me at about mile 20 of the 2003 Flying Pig Marathon. 2. Just crossing the finish line. 3. My favorite looking marathon medal.

May 3, 2008

Fat and fit no more...not me, but according to research.

One reason I run slow is that I carry a few extra pounds on my frame. However, I don't run for speed. I run for health figuring that even if I don't lose weight, at least I'll be avoiding the grim reaper for a few years (hopefully). But a recent study burst my fat but fit balloon. It found that women 45 years and older who are normal body weight (Body Mass Index less than 25) and active (burn more than 1000 calories per week which about the amount from running 10 miles per week) have less heart problems. The bottom line (no pun intended), run AND eat less.

Below: Me trying to look less fat between two flying pigs at the Cincinnati Flying Pig Marathon in 2002.