Soldiers often fail to drink enough water, especially when training in the heat. Water is an essential nutrient that is critical to reaching your best physical performance. It is also important for good health because it plays an important role in maintaining normal body temperature. The evaporation of sweat helps cool the body during exercise, so water lost through sweating must be replaced because lack of hydration can lead to poor performance and possible injury. Sweat consists primarily of water with small quantities of minerals like sodium. Cool, plain water is the best drink to use to replace the fluid lost as sweat. Experts recommend drinking water before, during, and after exercise to prevent dehydration and help enhance performance.

Sports drinks, which are usually simple carbohydrates (sugars) and electrolytes dissolved in water, are helpful under certain circumstances. There is evidence that solutions containing up to 10 percent carbohydrate will enter the blood fast enough to deliver additional glucose to the active muscles. Although this can improve endurance, there is no substitution for water.

During prolonged periods of strenuous exercise—1.5 hours or more—you can benefit from periodically drinking sports drinks with a concentration of 5 to 10 percent carbohydrate. Soldiers on extended road marches can also benefit from drinking these types of glucose-containing beverages. During intense training sports drinks can provide a source of carbohydrate for working muscles. On the other hand, drinks with more than 10 percent carbohydrate in them, like soda pops and most fruit juices, can lead to abdominal cramps, nausea, and diarrhea. Therefore, these drinks should be used with caution during intense endurance training and other similar activities.