Understanding late summer hiking conditions and how they effect the body
By BEN PIERCE Chronicle Outdoors
Ever been hiking in September on one of those days when the sun ducks in and out of the clouds? You’re sweating one minute and chilled to the bone the next, right?
Under such conditions, it can be tough work finding that happy medium where you’re not peeling one layer off just to add two more. You’re caught in a perpetual dance loading and unloading your windbreaker and fleece from the top of your backpack, cruising when it’s cool and slogging when it’s hot.
“This time of year we can easily hit 90 degrees during the day and down to 30 (degrees) at night,” said Steve Erickson, director of recreational sports and fitness for Montana State University. “That’s Montana – you can run your air conditioner and your heater in the same day.”
September is one of those tricky months for hiking in the backcountry. Like any time of year the weather can change quickly. Acknowledging the conditions and understanding how your body responds to them is key to a comfortable and safe hike.
When it comes to heat and cold, human body functions are dependent on chemical reactions within the body and blood circulation. Those reactions and your circulatory system perform at an optimum when your body temperature is at or near 98.6 degrees Fahrenheit.
When you are hiking – or performing any type of strenuous activity – your body produces heat. Approximately three-fourths of the energy your body converts during periods of exercise is released as heat, one-fourth as motion.
As you push your body to perform at a higher level, more and more heat is generated and the body must work even harder to dissipate that heat. As your body temperature rises, your heart rate increases and your blood vessels expand. Blood flow through the outer layers of your skin helps cool your internal body temperature.
During periods of high humidity or hot weather – like when the clouds break, the temperature shoots up 30 degrees and you’re still bundled up in that fleece – your body may not be able to reduce its temperature quickly enough through blood flow alone. In this instance your sweat glands release perspiration. Heat is transferred from the body through your pores to the surface of your skin where it manifests as sweat and evaporates.
When the body is working strenuously and blood is being utilized near the surface of the skin for cooling, there is less of it available to perform other vital tasks. As a result, blood flow to the brain, muscles and internal organs is limited. Add to that the quart of fluids an hour lost through sweat during strenuous hiking and that, in a nutshell, is why your body slows down while working hard in hot weather.
If you push it too hard, you might begin to feel the effects of heat exhaustion.
The symptoms of heat exhaustion include headache, nausea, muscle cramps, thirst and dizziness, Erickson said. Taking a 30-minute break in the shade, removing heat-insulating clothing and consuming fluids are often enough to reverse the effects.
“Of course if it is 100 degrees out, you might want to rest a little longer,” Erickson said.
On the other end of the spectrum – or in our case the next passing cloudbank – you’ve got cold temperatures. In some ways the body responds to cold similarly to the way it responds to heat, just in reverse.
When you get cold, blood flows away from the skin and extremities toward the center of the body in an effort to keep your core temperature at 98.6 degrees Fahrenheit. Rather than sweating the body may shiver, effectively tightening the skin and shaking the muscles in an effort to conserve and generate heat.
The effect of blood flow toward the body’s core allows exposed skin and extremities to cool. If the body is exposed to cold temperatures for extended periods of time and not sufficiently heated, frostbite or hypothermia can occur.
The symptoms of hypothermia are similar to the effects of altitude sickness, Erickson said. Patients may exhibit lightheadedness, weakness, fatigue, headaches, muscle cramps, nausea, irritability and combativeness in extreme cases.
Perhaps the most troubling symptom of hypothermia, however, is that the patient may not be aware of their own symptoms.
“I have seen it happen and people don’t know what they are doing,” Erickson said. “They don’t understand what is happening to them and if someone else doesn’t notice there is a problem – that is when you can run into severe problems.”
Fortunately, an array of lightweight clothing that both insulates and breathes is readily available for hikers.
“It is nice to have a wicking material like wool or polypropylene to pull (sweat) away from your skin,” said Sharon Duggar, owner of Girls Outdoors on North Tracy Ave. “When you sweat, if you have on a garment that is going to keep that moisture near your skin, you will cool down very fast. When you wick it away, it helps you dry and regulate your body temp.”
Still, Duggar said, layering is your best bet.
Erickson said it all comes down to using common sense and good judgment before heading into the hills.
“It starts back with all the basics – letting somebody know where you are going, making sure everybody on your trip knows the weather and how strenuous the hike will be, having the right clothes – the simple stuff that is what you need.”
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