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Summer Sports in Phoenix, Arizona: How to stay healthy and uninjured. A variation on the Park City article for
those who live in markedly warmer climates.


As summer suddenly comes to Phoenix we put away our skis and snowboards (if we even have them) and turn to
our favorite activities for warmer temperatures. Have you thought about taking up a new activity, but were
reluctant because of some old injury or nagging pain or perhaps some new injury that you feel might impose
limitations? Are you concerned about heat exposure? Will you hibernate indoors until things cool off? Are you
new to Phoenix? How do we know what is best? Do you want to add some life and excitement to the hottest time
of the year in Phoenix, but don’t know where to start? If you have these questions or others then this article is for
you. This article is one in a series that will be published this summer. It will answer your questions and give you a
basis for making decisions about what you can and what you should do. It will enable you to have fun and stay
healthy.

If you have any history of heart conditions or family history or are unsure of whether you are in a high risk
category for heart problems always consult your doctor before undertaking an exercise program. This is good
preventive medicine.

Walking is a good way to stay healthy, burn calories and enjoy the outdoors. Walking for four or more hours per
week has been shown to decrease the risk of hip fracture in postmenopausal women by 41%. Brisk walking
greater than 2 mph reduced the risk by 61%. Exercising on a regular basis increases the natural release of
endorphins which have been shown to have a positive effect on a person’s sense of well-being. If you can time
your exercise to end before a meal time, the natural elevation of your blood glucose that occurs with exercise will
reduce your appetite afterwards for about one to one and one half hours. Eating less in turn with a higher
metabolic rate from the exercise will help with weight reduction if needed. Walking does not burn as many calories
as hiking but it is easier for all walks of life. I would define walking as moving on even surfaces with only gradual
changes in elevation and hiking as moving on varied terrain with more  moderate changes in elevation. Walking 2
mph (30 min./mile) burns 180 calories per hour for a 150 lb. person. For every ten pounds less or more subtract
or add 12 calories per hour to the equation and you can calculate your energy expenditure. Increasing the pace
to 3 mph (20 min./mile) increases the energy used to 240 calories per hour for a 150 lb. person. For every ten
pounds less or more now add or subtract 16 calories. Walking 4 mph (15 min./mile) utilizes 300 calories per hour.
Add or subtract 20 calories per hour using the same formula as above. If you want to determine what type of
aerobic conditioning you are getting I would recommend that you take a look at the chart in the fitness center and
either memorize or write down your pulse rate specific for your age for fat burning, aerobic and high intensity.
When you take your pulse, the carotid is more accurate, but the radial pulse at the wrist will do.

Here are some pointers to help you stay uninjured and healthier while walking. Planning is important. If you can,
walk early in the morning or towards the evening planning to get back before nightfall. As visibility decreases one
is more likely to sustain an accidental fall. Mornings are cooler but not all of us are “morning” people. In the
cooler temperatures you have less of a tendency to become dehydrated which can happen quickly and
insidiously in drier climates such as Phoenix. The sun is at a lower angle especially before 10:00 AM and after 4:
00 PM so your exposure to harmful UV (ultraviolet radiation) will be far less. In Phoenix, as it is still so warm even
at 4:00 PM one might be advised to wait until even 5:00 PM or 6:00 PM to perform activities more safely outdoors.

It is a good idea to wear a hat with as broad a rim as possible to shelter your face from the sun as this is where
many of the skin cancers originate. Make sure the hat protects the ears as well as the back of the neck or wear a
high collared shirt. If you are going to have sun exposure wear sunblock with at least a 30 rating, higher if your
skin is sensitive. Try to time your walk so that it is in shaded areas. Wear sunglasses with UV protection. Wear
clothing to protect exposed areas. Remember that not all clothing is the same. Clothing has a UPF (ultraviolet
protection factor) rating. Wearing clothing with a UPF rating of 20 will reduce UV exposure by a factor of 20.
Darker fabrics and more tightly woven fabrics usually block more UV radiation. The disadvantage of dark clothing
is that it absorbs more sunlight, so the ideal fabric if you can find it would be a light colored material with a UPF
rating at or above 20. Looser clothing gives better protection and allows for better cooling.

UV radiation is one type of radiation emitted by the sun. It becomes more intense closer to the equator and also
at higher altitudes such as in the mountains. Even in Park City on a cool day in the summer we can get a
tremendous amount of UV exposure for this reason. Clouds do not necessarily block UV radiation. There is an
index called the UV Index and Exposure Level. The higher the number, the more UV you will be exposed to. At
levels of 5 (moderate) to 10+ (very high) it is best to take every precaution as outlined in this article to protect
yourself from the sun. Why is it important to protect yourself from UV radiation? Exposure to UV radiation can
cause skin cancer, cataracts and other problems as well. The risk of skin cancer is related to the amount of UV
exposure over a lifetime, especially in childhood. Remember to protect your children as often they forget or are
oblivious to the amount of sun exposure they are getting. More than 90% of skin cancers occur on exposed skin,
particularly the face, ears, neck, forearms and hands.

Wear layered clothing as temperatures can change rapidly. Most sporting goods stores sell good walking shoes.
You could use walking shoes, cross trainers or even running shoes. Ask lots of questions about this at your local
shoe store. Spend a lot of time trying on different types of shoes. Quality usually goes up with price and your feet
will thank you. If your shoes are new be very careful to gradually get used to them rather than wearing them four
hours the first day. The best surfaces to walk on are level dirt paths or even grass such as a golf course. Make
sure it is allowed if you go to the golf course. These surfaces provide more cushioning and less impact to your
joints all the way from your feet to your back. If you have only the option of walking on asphalt or concrete make
sure your shoes have plenty of extra impact absorption built in to them.

It is very easy to become dehydrated without knowing it. Bring plenty of water or fluids. There are several ways to
do this. One is to use a small pack, such as a day pack. This is also a good place to put extra clothing and sun
block lotion. Or you could use a camelback which can be carried like a backpack and has a tube with a nozzle
which can drape over your shoulder for easy access to water. These items are available in the BX. You can carry
a water bottle but this gets old after a while unless you are out for a very short walk and usually you can not carry
enough fluid in your hands to compensate for what you are losing. A good rule of thumb is to bring one small (16
oz.) water bottle per two hours of walking. For strenuous walking of an aerobic nature it is recommended to drink
24 oz. per hour. In a running race, one can lose up to 68 oz. per hour in the form of sweat!! As one becomes
dehydrated, the digestive system does not work as efficiently so you absorb less of the water or fluid you drink
sometimes leading to a vicious cycle where you are becoming progressively more dehydrated despite drinking
because the water you are drinking is not being absorbed. For walks longer than two hours, bring fluids which
also replace electrolytes such as juice or Gatorade, etc. This is because water alone does not replace the salt
(sodium chloride) lost in sweat. Also the carbohydrates in sports drinks give you more energy as long as the
carbohydrate content is less than 10%. Concentrations above this value are not as well absorbed and may cause
diarrhea. Remember to have your children stay properly hydrated. Since kids have a lower overall blood volume
(they’re smaller) they become dehydrated more quickly and they often ignore the signs of thirst and forget to
drink enough.

So what makes us thirsty and is thirst an indication of dehydration? A recent article from Dartmouth Medical
School defines thirst as beginning when the concentration of blood has risen by less than two percent. Most
experts define dehydration as a five percent rise in the concentration. So when you are thirsty you are not
necessarily dehydrated but it is an indication that you need to drink more. Why should you drink more?? At a 2%
increase in blood concentration athletic performance drops by 10-20%. It is also just plain good preventive
medicine for the three types of heat injury that can occur. These heat injury syndromes are almost always
caused by not drinking enough. The three stages to heat illness are in order heat cramps, heat exhaustion and
finally heat stroke. Heat cramps are thought to be caused by dehydration and electrolyte imbalance. The
dehydration is from excessive fluid loss usually in the form of sweat or evaporation and the electrolyte imbalance
occurs because the sweat contains electrolytes which are not replaced as fast as they are being lost. These
cramps occur in the arms, legs or abdomen. When you get to this point it is time to stop and cool down and drink.
Heat stroke can be fatal and often heat exhaustion progresses rapidly into heat stroke.

It is a good idea to stretch but not before you walk. If you stretch when your muscles are cold and not warmed up
you are more likely to be injured. After walking about ten minutes, then stretch. Make sure you stretch your
dorsiflexors, achilles tendon, hamstrings, quads and iliotibial band at the hip and the knee. The iliotibial band is
frequently forgotten and frequently injured. The dorsiflexors are the muscles in the front of the leg and are
heavily used in walking. A good stretch is to put the top of your foot on the ground behind you and gently stretch
the front of your leg. Stretch your hamstrings by touching your toes with your knees straight. Quads can be
stretched by lying on your side and gently pulling your leg behind you by grasping on your foot. The ideal is if
your foot can touch your buttocks with your hip in line with your torso. Finally stretch your iliotibial band by lying
on your side and stretching your leg over the other leg while keeping your shoulder blades firmly on the ground.
If you have any questions on correct stretching the base gym at Luke AFB has wonderful pictures posted
everywhere that show you how to do it correctly. It also gives you an extra excuse to go to the gym. If there is no
place to sit for stretching, bring a small towel in your pack. (We come to that pack again)

If you develop pain while walking turn around and go home early. Pain is not a good symptom when walking and
is usually indicative of an injury or inflammation. If you have pain, you should see your doctor and have it
evaluated before exercising further. Most painful conditions arising from walking can be attributed to improper
stretching or inflexibility which can gradually build up. This usually happens because people don’t stretch enough
or don’t know how to stretch properly. I see this in my clinic on a daily basis. These conditions are usually easy to
treat. The key to overcoming this is to exercise and stretch regularly in the “pain free” zone and very gradually
increase your exercise time and flexibility. Many people make the mistake of trying to do too much too fast. Other
types of pain originate from early or even advanced osteoarthritis. Sometimes this diagnosis will manifest itself
when one begins some type of new exercise program. Dietary supplements such as glucosamine and chondroitin
sulfate have been studied and shown to help with arthritis and joint stiffness, but not all brands are the same, so
ask your doctor for recommendations. Dietary supplements are not regulated by the FDA. There are non-
operative treatments available that are FDA approved for arthritis of the knee. These are in the class of
hyaluronans. This is a safe treatment for arthritis, even mild arthritis and has been shown to work in numerous
medical articles from reputable sources. There are several types available and they are not all the same.
Remember questions are good and those who do not ask are only fooling themselves. It’s time to start exercising!

Have fun, whatever you decide to do. See you there, keep on walking.

Dr. Mark Hopkins is a Board Certified Orthopedic Surgeon specializing in sports medicine. He has worked as a
volunteer physician for the United States Olympic Committee. He is an avid mountain biker and likes hiking and
walking in the summers. He has been assigned as a reservist to the 944th Fighter Wing at Luke AFB since
August 2001.

Mark Hopkins, Col, USAFR, MC
Board Certified Orthopedic Surgeon
P.O. Box 680518, 1205 Ironhorse Drive
Park City, Utah 84068