If you are anything like me and you enjoy getting outside and exercising, this time of year can be especially great because of the sunny weather, yet very dangerous because of the heat. I found this great article at http://www.runnersworld.com and thought I would share...
How to Run in Hot Weather
TURNING UP THE HEAT
How exactly does hot weather affect runners? Our zealous correspondent endures a scorching, sweaty hour in a heat chamber and staggers back with some answers.
By Amby Burfoot
From the August 2009 issue of Runner's World
Reality Check: Know the Risks
MYTH Only dehydrated runners are at risk.
REALITY High humidity and intense effort can cause heatstroke in hydrated runners.
MYTH Only long runs cause heatstroke.
REALITY Fast, hard, shorter running—in 5-K or 10-Kraces—can also cause heatstroke.
MYTH Heatstroke occurs only if the weather is hot and humid.
REALITY Heatstroke can occur in mild conditions if an athlete is overfatigued.
MYTH Heatstroke victims stop sweating.
REALITY Heatstroke also develops in athletes who are still sweating.
Just How Hot Was He?
An hour in ideal conditions vs. an hour in heat
I ran identical workouts—one hour at 8:30-per-mile pace—on consecutive days in the University of Connecticut's environmental chamber. The first run was in 53-degree conditions, the second at 90 degrees. On the hot run, my heart rate, temperature, and sweat loss spiked to levels that diminish performance while increasing health risks, a reaction Lawrence Armstrong, Ph. D., editor of Exertional Heat Illnesses, calls "classic."
BODY MEASUREMENTS AT 53° F
Heart rate 158
Rectal temperature 101.98
Lactate .978 mmol/liter
Sweat loss 27.05 ounces
Percent dehydrated 1.3
Plasma volume -0.2%
BODY MEASUREMENTS AT 90° F
Heart rate 175
Rectal temperature 103.45
Lactate 4.04 mmol/liter
Sweat loss 54.10 ounces
Percent dehydrated 2.6
Plasma volume -10.9%
Be Cool
Play it smart when running In the heat.
University of Connecticut heat experts Doug Casa, Ph. D., and Larry Armstrong, Ph. D., both lifelong runners, recommend the following strategies to keep you safe and healthy in the summer heat.
Give yourself eight to 14 days to acclimatize to hot weather, gradually increasing the length and intensity of your training. In that time, your body will learn to decrease your heart rate, decrease your rectal temperature, and increase your sweat rate.
Run at the coolest time of day, usually in the morning before or just after sunrise.
Run in the shade—on trails or tree-lined roads—to avoid heat gain from solar radiation.
Wear light fabrics and as little as possible to encourage evaporation of sweat.
Hydrate appropriately before, during, and after your run. But be careful; overhydrating can be just as harmful.
Run a shorter distance than you might normally run in cooler weather.
Run slower than you would in cooler weather. Don't expect to match times that you achieved in better conditions; it's not possible in the heat.
Run with friends, or let someone know where you're running and when you'll return.
Warning: Heatstroke Ahead
Avoid hot-weather running if you are experiencing any of the following conditions or situations, as they put you at risk of heatstroke.
Sleep loss
Unusual fatigue
The sense that you're about to "come down" with something A long workout A heat wave
An extensive heat exposure (mowing the lawn, a hot soccer match)
Reduced sweating
Fever or illness
How to Run in the Heat at Runner's World
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