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When Youíre Hot, Youíre HOT!
by David L. Hough
The ride south over the Siskiyou Mountains from Oregon to California started out cool enough. Up at 4,000 feet, it was chilly enough that I was glad I had added the jacket liner and neck warmer. But a hundred miles later, as I descend down into the Sacramento Valley, the temperature begins to soar. By the time I reach Oroville, the temperature signs are flashing 118 F. Itís another hundred and fifty miles to the rally site at Mariposa in triple-digit temperatures.
A rider passes by in the opposite lane, jacket bungeed on the back, bare chest exposed to the hot blast. I wave, but there is no response. His exposed skin is red, and he doesnít even appear to have noticed me, a bad sign that heís on the fringe of heat exhaustion. I donít wish any problems on a fellow motorcyclist, but there are lots of riders who have to contribute to the statistics before they crack the code.
To continue the ride, I go into hot weather survival mode. Full riding gear, including riding pants, leather boots, and gloves, and a knit neck "cooler" saturated with water. As quickly as the fabric dries out in the blast-furnace wind, I flip the faceshield open, squeeze a gusher of water down my chin, and slam the faceshield shut again. The water dribbles down to wet the neck cooler and my shirt inside the jacket. About 10 seconds after the water penetrates the neck cooler, it cools from evaporation in the hot air, and sucks some heat out of my neck.
I stop at a fast-food outlet every few miles to replenish the water bottle with ice and water. Whether riding or stopping for water, other people stare at me in disbelief. Peering out of their air-conditioned cars, or sitting in an air-conditioned restaurant, they just canít understand how anyone could tolerate being outside during a heat wave, bundled up in heavy riding gear.
Your body has automatic "thermostats" to protect the core organs from heat stress, including sweating, vasodilation, increase in heart rate and reduction of blood pressure. If these tactics don't keep core temperature within the redline, the body gives you warnings such as heat cramps. If you donít take care of the problem, it gets more serious, including heat exhaustion and heat stroke.
The body has sweat glands to keep the skin damp. The evaporating sweat sucks heat from the skin, and transfers it to the air. Of course sweat is primarily water, so itís critical to keep replenishing the supply. That's one reason why we need to drink about a pint of water every hour during hot, dry conditions. One problem for motorcyclists is that at highway speed, the sweat glands may not keep up with the evaporation. Or, if the sweating uses up too much water, your body temperature regulating system goes on the fritz, like a dry battery.
To help cool down the core, blood vessels enlarge to circulate more blood (and therefore body heat) towards the skin. If ambient air temperature is lower than body temperature, excess heat can be absorbed by the air. But if the air gets hotter than the skin, the increased blood flow simply soaks up more heat from the air and pumps it back to the core.
Heart rate and blood pressure
The heart responds to increasing heat ("hyperthermia") by increasing the heart rate to pump more blood into those enlarged blood vessels. As the air temperature rises, heart rate (pulse) can increase 50% to 70% faster than the normal resting rate. The increased flow causes blood pressure to drop, and blood flow is shunted away from muscles and brain, towards the skin. Consider the implications of those changes on a motorcyclist. The lowered blood pressure reduces muscle control and brain activity, and more blood is pumped towards the skin--where it is vulnerable to road rash
Symptoms of trouble
The human body won't take much of an increase in core temperature without complaining. The symptoms of overheating are leg cramps, tired muscles, headaches, dizziness, and even fainting. The various symptoms are trying to tell you how overcooked you're getting.
Muscle cramps caused by heat usually effect the legs and lower abdomen first, then the arms. Heat cramps are a symptom that the body's electrolytes are running low. Itís not smart to ignore muscle cramps. Find some shade and take a break. Sip water or an "exercise" drink Exert firm pressure or massage the cramped muscles to relieve the spasms. If youíre still in pain, the recommended first aid dose is 1/2 teaspoon of table salt per half glass of water every 15 minutes.
Heat exhaustion occurs as the body continues to shunt blood away from the brain and muscles. Symptoms of heat exhaustion include:
1. Headaches, dizziness, nausea, momentary fainting
3. Tiredness, weakness
4. Profuse sweating
5. Pale, clammy skin
6. Approximately normal body temperature
If you begin to feel these symptoms during a desert ride, take immediate action before you pass out. 1. Get into some shade, preferably into an air-conditioned room.
2. Loosen clothing and wet down skin or undershirt to increase evaporative cooling.
3. Slowly sip water, or salt water solution, same dose as for heat cramps. Avoid alcohol or caffeine.
4. If you feel faint, lie down and get feet raised above head level.
5. If you canít keep the salt water down, get emergency medical aid. You may need an intravenous salt solution.
6. Even after you begin to feel normal again, consider staying out of the heat for a day or two. Your body needs some time to recuperate. If you are on a long trip, consider a 24 hour layover in the next air-conditioned motel.
If you experience heat exhaustion and just try to "tough out" the heat without getting cooled down and rehydrated, the body thermostats will begin to fail. Core temperature continues to rise (may go as high as 106 or 107 degrees F.), sweating stops, the heart beats even faster, and you may pass out. If you are coherent enough to recognize the symptoms, immediately get medical aid while you are still mobile. And watch your riding buddies for any of the following heat stroke symptoms.
1. Victim incoherent, staring vacantly, blanking out, or unresponsive
2. Skin hot, red, dry (no perspiration)
3. Rapid pulse
4. Body temperature elevated
Yes, heat stroke is life threatening. Itís a medical emergency. Donít be bashful about calling 911 for assistance. In the meanwhile,
1. Get the victim into some shade, out of riding gear, and cooled down by any means available. If possible, get the victim into an air-conditioned room, or use fans to help provide evaporative cooling.
2. Repeatedly sponge skin with cool water or rubbing alcohol. Apply cold packs or ice cubes if you can get them. The goal is to get body temperature below 102 degrees F.
3. Don't give the victim any stimulants, especially not any alcoholic beverages.
4. If the victim's temperature begins to rise again, repeat the cooling process.
5. As soon as possible, get the victim to emergency treatment.
Avoiding the Ugliness
Even after a heat stroke victim has been cooled down and rested, the ugliness isnít over. Itís not uncommon to have intestinal upset for a week or so, with food coming out both ends of the pipe. I know youíd rather avoid that sort of ugliness.
People from cooler climates often react to hot weather by removing clothing. That helps cool the skin--providing air temperature is less than body temperature. Heat transfers from a hot object to a cold object. Pick up an ice cube, and it feels cold. Whatís happening is that the ice is rapidly absorbing heat from your skin. Even if the air is 89F, the air will absorb heat from your skin (assuming your body is around 99F). Now, consider what happens when you curl your fingers around a hot cup of coffee. Your skin rapidly absorbs heat from the cup, because the cup is hotter than your hand. The same thing occurs when the air temperature is hotter than your body temperature.
You may think your body is hot at 99 F, but itís "cold" compared to air at 118 F. If you expose your skin to air thatís hotter than you are, your body just soaks up more heat.
The lesson here is that if air temperature is in the 80s or 90s, it helps to open up the jacket vents, or wear a mesh jacket. But once air temperature climbs above 99 F, the best way to keep from getting cooked is to keep your insulation on, and the vents closed. Desert nomads wear long, loose wool garments, both to keep the sweating skin in the shade, and to insulate the body from the hot air.
With the temperature in triple digits, I wear my leather gloves and insulated riding. My feet are down in the air stream thatís first been heated up by the pavement, and then heated some more by the engine. Are my feet hot? Sure, but not as hot as if I were wearing thin boots or shoes that exposed my ankles.
Same for the helmet. Wouldnít it make sense to crack my visor when itís really hot, or at least open up the helmet vents? Nope. Any hot air allowed to reach my skin will heat up the skin, not cool it down. Inside my helmet at 118F, Iím sweltering, but the temperature is probably under 100 F. That crushable helmet liner inside the shell is there to cushion my brain against impacts, but itís the same expanded polystyrene foam they use to make insulated picnic coolers. So, the helmet actually provides insulation against the hot air.
One additional concern about exposed skin is sun and wind burn. Even if you wear heavy duty sunscreen to protect against a nasty sunburn, the wind at motorcycling speeds can also irritate the skin. If youíre riding more than a few miles, itís best to keep your skin covered.
More physics now. When water evaporates, it cools down. Blow hot air through a wet bandana, and the bandana cools down. Cooling the skin cools the blood, which cools down the whole body. Evaporative cooling works best on areas of the body where there are large blood vessels close to the skin: the groin and the neck. A motorcyclist's groin is too close to the engine and too far out of the air stream. That's why wearing something wet around your neck is so important.
The bad news is that evaporative cooling only works well in dry climates. When the humidity is already high, (you're 99/99 in Missouri in August--99 degrees and 99 percent) neither perspiration nor the water in your neckband evaporate very well. Limited evaporation; limited cooling. But of course there is shade in Missouri, so the best tactic may be to simply take more breaks in humid climates. Or, you can ride early in the morning when itís cool, and rest in the shade in the afternoon.
For those of us riding in the deserts of Washington, Oregon, and California, the air is relatively dry, so evaporative cooling works very well. A wet bandana around your chin will cool you for a few minutes, but the hot wind blast will quickly evaporate all the water. You need to keep replenishing the water every few minutes. Better yet, wear thicker fabric that holds a lot more water.
For instance, Aerostich makes an "Evapodanna" made of the same fuzzy material used in camp towels. ("evaporative bandana", get it?) You just saturate it with water, and wrap it around your neck. Occasionally dribble some water on it and it will continue to cool all day. There are also some tubular neckties containing special polymer crystals that soak up a huge quantity of water. They are an advantage for slow speed activities such as golf, but the crystals release the water very slowly, and canít give off enough water at motorcycling speeds to provide much evaporative cooling.
Keep Your Tummy Tank Full
The other important tactic for hot weather is to drink lots of water, to replenish your electrolytes and refill your sweat glands. Weíre talking at least a pint per hour. Exercise drinks containing "electrolytes" (salts) are acceptable, unless you have high blood pressure. And flavored drinks may be very high in sugar, too. Carbonated soft drinks are better than nothing, although it would be best to get the water without large doses of salt, sugar and chemicals. Almost all grocery stores and convenience markets have chilled filtered water in plastic bottles, handy for both drinking and wetting down your bandana.
More than a few riders carry a water bladder, such as a "Platypus" carried on the back in a fabric holster, or in a jacket pocket. Some water bladders can be pressurized with small pumps, and evaporative cooling wrappers are available to help chill the bladder. Aerostich is a good source of serious hot weather hydration devices. Aerostich: (800) 222-1994 or www.aerostich.com. You can also find water bladders at sporting goods stores such as REI in Seattle.
In hot weather, avoid alcoholic drinks. Obviously, alcohol reduces judgment. Whatís not so obvious is that alcohol stimulates abnormal heartbeats, depresses the pump function of the heart, and actually dehydrates the body. Alcohol does all the wrong things for a motorcyclist in the desert.
So, when itís really hot, keep your jacket on, and soak down your T-shirt. Wear a wet neck cooler, and keep dribbling water on it. If youíre getting too hot, or start feeling any hints of muscle cramps or heat exhaustion, donít just keep riding. Take steps to cool down while youíre still thinking clearly. Take a break in the shade, or stop at a convenience store and buy a bag of crushed ice to stuff inside your jacket. The melting ice water will soak your gear and provide evaporative cooling even after the ice is gone.
In general, higher elevations are cooler. If itís really hot down on the valley floor, consider an alternate road with a higher (cooler) elevation. Sometimes you donít have any alternative other than crossing a desert. But you can adjust your schedule. One tactic is to hibernate at a cool motel during the heat of the day, and head out after dark, when the temperature is lower.
Adjust your thinking
If you live in a temperate area where the thermometer seldom rises above 90F, you need to readjust your thinking for those forays into hotter territory. Remember, insulate your skin from the sun and hot air, use evaporative cooling around your neck, and drink lots of water. Oh yeh, learn to ignore the stares of other motorists and dehydrated bikers who think youíre crazy to wear heavy gear on a hot day.
David Hough is a long-time motorcyclist and journalist. His work has appeared in numerous motorcycle publications, but he is best known for the monthly skills series "Proficient MotorcyclingĒ in Motorcycle Consumer News, which has been honored by special awards from the Motorcycle Safety Foundation. Selected columns were edited into a book "Proficient MotorcyclingĒ published by Bowtie Press. He is also the author of "Driving A Sidecar OutfitĒ. A pocket handbook, "Street StrategiesĒ is also on the market as is More Proficient Motorcycling.
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