The heat of the night--that's worse than the scorching sun of the day. No relief, no chance to open the windows to a cool breeze. No possibility to get a second wind to battle the hot dry air that comes with the sun. The occasional stretch of hot spells that come every summer should be a reminder of how fortunate we are to have such incredible weather most of the rest of the year.</p><p>Some in the Central Valley can simply stay inside with the A/C on with the only evidence of summer heat being the numbers and ominous icons that show up on a weather map on the evening news. Others are forced to endure the summer conditions with no respite whatsoever. Try driving in the middle of the day with the windows down as the thermometer tops 112 degrees. Imagine our brothers and sisters in the Middle East who have to do that in full battle gear. Wow!</p><p>Obviously when it is so hot some precautions must be taken to prevent dehydration. Given time to adjust, the body has remarkable abilities to adapt to hot conditions. There is usually a gradual warming trend that allows us to slowly increase our tolerance. Some people must become acclimated to the summer heat because their livelihood depends on it. For them the home A/C set at 72 degrees in the evening may feel nice but it's probably the worst thing they can do because they never get used to the heat.</p><p>Consider athletes that should purposely and methodically become acclimated to hot weather. It is suggested that 80 percent acclimatization can be expected to occur after the first seven to 10 days of training. Final stages of acclimatization to heat are marked by increased sweating and reduced salt concentration in the sweat. Sodium losses from sweat are greatest during the early acclimatization process so emphasis on salty foods like pickles, chips, canned soups can ensure the most complete rehydration during the first week of conditioning.</p><p>Water and diluted carbohydrate drinks should be served cool and should be made freely available at all times. Athletes and those working in the heat should drink, at a minimum, every 15 to 20 minutes. The old idea that water should be withheld from athletes during workouts has no scientific backing. Drinks with high carbohydrate concentrations like soda, Kool-Aid and juices should be avoided. Beverages containing caffeine, alcohol, and carbonation should not be used because they can actually cause dehydration.</p><p>Those working in the heat should be observed carefully for signs of trouble, particularly those who lose significant weight and the eager athlete who constantly competes at his or her capacity. Some danger signs are nausea, incoherence, fatigue, weakness, vomiting, cramps, weak rapid pulse, visual disturbance and unsteadiness.</p><p>A great way to find out how much fluid is lost is to weigh each day before and after practice or work. Generally a 2 percent weight loss through sweating is safe. More than 3 percent weight loss is in the danger zone and the athlete should not be allowed to practice in hot and humid conditions. Drinking 16 to 32 ounces of fluid per pound of weight loss before the next practice will replace the fluid lost. Relying on thirst alone is not enough.</p><p>Another way to monitor hydration is to check the color of the urine in a cup (not the toilet bowl). Pale yellow color is ideal; gold or orange indicates mild or moderate dehydration while brown urine is evidence of severe dehydration.</p><p><i>Chuck Newcomb, MS, RD, CDE is a consulting Registered Dietitian currently providing medical nutrition therapy services for Memorial Hospital Los Banos. He has a Masters of Science in Clinical Nutrition from New York University. E-mail questions to the Attention of ChuckRD at: MHALosBanos@SutterHealth.org.</i>