How’s your riding on these hot summer days? Feel mostly like wilting? Beginning early in the morning and finishing before the heat of the day, say by 10:00 am is a good way to escape the bulk of the heat. The early morning rides are really nice, particularly once you break into a sweat. With the humidity so high the movement on the bike really energizes those water molecules on your skin and in your jersey and they zip away pretty quick. When temperatures are below 80 or 85 you can still benefit from evaporation, even at slow speeds. Once it warms up into the 80’s and the humidity hovers between 60 and 70 percent and the sun begins to move up the sky, the benefit seems to evaporate instead of the sweat.

Sweat is one of the primary ways the body reduces heat build-up and an increase in body core temperature. Other methods are simple loss of heat by breathing, normal elimination of body waste and convection from the surface of the body. But these less effective defenses are not enough to cool us on hot summer days. We need sweat and we need dry, cool and/or moving air around us.

Many years ago my great-grandmother used to expound on such things. I remember her saying, "Horses sweat, men perspire and ladies just glow." And that was before air conditioning and in the wake of Queen Victoria’s reign. Pretty much now we all do what horses do when it gets hot, that is, we lose fluids and we lose salts. After a good ride have you ever rubbed your temple with your finger and felt a gritty deposit behind your eye? That is salt deposited as a result of the evaporation of sweat. If you put it to your tongue, it tastes salty. No big deal, it’s your sweat. Salt loss and fluid loss are the devils of hot-weather cycling.

The word salt is used to cover various compounds. Sodium and potassium are the ions or body electrolytes most directly influenced by heavy sweating. Fluid loss causes an increase in viscosity or thickening of the blood that can put considerable strain on the heart. Salt loss causes muscle weakness and leg cramps. Excessive losses of either can cause heat prostration and heat stroke leading eventually to death. Early symptoms are headache, weakness, muscle soreness and cramps. Strongly colored urine or no urine output for several hours can be one of the earliest signs of dehydration. If you pee during a ride and soon after arriving home, chances you’re in good shape. If not, weigh yourself after getting home. Compare that weight with your normal weight. Loss of three to eight pounds during a ride, depending on your normal weight, can put a particular strain on your system as well as make you very tired. Recovery from such a ride is slow and may take several days or weeks depending on the general condition of your health. Continued abuse of your body following excessive depletions may bring on a severe case of over training. That can take months out of your cycling time. Don’t ever go there! Rest is important for the cyclist.

Replacing fluids while cycling may seem unnecessary. During cycling, fluid loss may not be realized through immediate development of thirst. You’re sweating, staying cool and the breeze feels great. Try to keep in mind that every drop of fluid that is loss through sweating must be replaced for the body to have its normal level. Also lost in the sweat is salt. Most sports drinks, and of course, water, do not replace salt in the quantities lost during hot weather cycling. Do not be satisfied with your sports drink as a replacement for salt. Sports drinks actually remove a net amount of salt from the body, although at a slower rate than pure water.

So with all this much in the way of fluid/salt problems what can you do? On cold or cool days get a good meal and plenty of fluids, water, sports drink (full strength) in you before you start. Don’t over drink. That just makes you uncomfortable, leaches salts and may require that you find a lonely patch of woods. Drink normally with your meal. Top-off with a glass of water or 12-16 ounces of sports drink (full strength) just before you begin riding. Carry a bottle of sports drink and a bottle of water or two bottles of sports drink with you. Remember that diluting a sports drink with water may cause you to lose more salt. You will need 12-24 ounces of fluid per hour of riding. Somewhere along the way you may want to refill, maybe at a country store. Keep that in mind when you plan your route. Oh, and don’t forget to carry some money.

When the heat of the summer burns down plan your route with a rest stop in mind. Do the usual with the sports drink and/or water before your ride. Tomato juice is a great way to get a little extra sodium and potassium in the morning before you leave home. You should take 18-36 ounces of fluid per hour on a hot summer ride. Drinking while riding in a pace line is an important riding skill. Learn it—solo. If you have a headache, stop for cool water. One to two gallons of fluid intake on a 100-mile ride is not unusual. If you begin having leg cramps stop for tomato juice, salted peanuts, or even a pinch of salt. Chase salt intake with cool water and then as you continue riding increase intake of sports drink. Leg cramps will often subside. Salt tablets were once the rage. Somehow they went out of style when it was learned that high blood pressure is aggravated by salt intake. Now, I understand they are being used once again by those who are involved in activities resulting in heavy sweating. An extra pinch of salt in a bottle of sports drink is also helpful in staving off leg cramps.

If you ride hard for 20 miles on a hot summer day and then stop for fluid, you may find it to be too late. Drink frequently, every 10 to 15 minutes along the way. Using thirst as a guide to drinking is no good. Once you are thirsty, it may be too late—you are already depleted. Fore some reason cycling and a strong sense of thirst don’t go hand-in hand. This is especially true for older riders. As we age our sense of thirst may come well after we have built up a serious fluid deficit.

For all of us, it is important that we be aware of our potential medical problems before becoming seriously involved in riding. These medical problems may be strongly influenced or may strongly influence what measures we can take to stay healthy. Check out and become aware of your health. Seek the appropriate medical advice. Got a medical problem you know about? Know your limitations and be sure others know about them as well—one of the benefits of bicycling with a group—use it.

- David M. DuMond