Every sunscreen has a sun protection factor, or SPF, which is a measure of its strength or effectiveness. Each of us needs a different SPF, depending on whether, and to what degree, our skin burns or tans. A tan is the direct result of melanin, a brown pigment found in the epidermis that is produced when skin is exposed to sunlight.
Melanin protects the skin by absorbing, reflecting and scattering ultraviolet radiation before it penetrates the dermis, or underlying skin. However, armor that it is, melanin can’t prevent all the negative effects of the sun, and is often representative of damage. That’s why we need to use sunscreens. To determine what SPF your skin requires, you must know how long it takes your skin to burn when unprotected and exposed to sunlight. As a rule of thumb, anyone whose skin burns, whether or not it turns into a tan, should use an SPF of 15. Check with your doctor or pharmacist if you are taking antibiotics, antidepressants or antidiuretics. Some of these medications increase your skin’s sensitivity to sunlight and may decrease the time it takes your skin to burn.
It’s summertime and you head out for a run. Before you even finish the first mile, your body feels as though it might ignite from the heat. It’s not your imagination. Fifteen minutes into your run and your body temperature could be as high as 5° F above normal. If you were to continue at this pace, fatigue and heat illness would no doubt take over.
The above scenario doesn’t have to happen. Drinking enough fluid, whether water or a sports drink, is imperative for exercising in hot or humid weather.
Maintenance of body fluids is essential to maintaining proper body temperature. Sweat cools your body by evaporating off your skin.
Visible beads of sweat that don’t evaporate only dehydrate you without the beneficial cooling effect. If you let your body become dehydrated, you’ll find it much more difficult to perform even the lightest of workouts.
But don’t wait until you’re thirsty to start replenishing those fluids. Chances are, by the time you actually feel thirsty, your body is well on its way to becoming severely dehydrated.
24 North Merion Avenue, Bryn Mawr, PA 19010 • 
