Seldom is water thought of as food. While it has no caloric value and does not provide any of the other nutrients, water is second in importance only to oxygen in maintaining life. Water constitutes approximately 60% of the total body weight, with 2/3rds of the water contained within the body tissues and 1/3rd outside the cells. While we can survive for weeks or even months, without food, we cannot tolerate water deprivation for more than a few days. Water is necessary for digestion, absorption, circulation and excretion. With respect to exercise, water plays two critical roles. First, it is important in maintaining electrolyte balance in the body. Second, it is a transporter of nutrients and byproducts to and from the cells, via the circulatory system.

Water intake is controlled largely by thirst sensations generated by a complex series of events in the body. However, these mechanisms do not always keep pace with the body's need for water. The sensation of thirst indicates that levels of water in the body are too low. It is important to remember that human thirst is a poor indicator of the body's water and electrolyte balance.

No matter how efficiently the kidneys do their job, body fluid balance depends on a strong thirst sensation to simulate fluid intake. If the athlete's thirst is used as the only gauge of water need, it may take 12 to 24 hours to replace the water deficit. During exercise and heavy sweating, it is recommended that athletes be encouraged to drink water before they feel thirsty. If too much water is ingested, the body can adapt rapidly by passing off the excess in urine.

The ability to lose body heat during exercise depends, for the most part, on the formation and evaporation of sweat. The amount of sweat lost during exercise, in turn, depends on one's skating pace, body size and the environmental heat stress. Skating in warm weather may evoke sweat losses in excess of two quarts per hour. Despite efforts to drink fluids during an event such as the marathon, sweating and the loss of water in the air athletes exhale may reduce body water content by 13 to 14%. Studies have shown that dehydrated individuals are quite intolerant of exercise and heat stress. Distance runners, for example, are forced to slow their pace by 2% for each 1% of weight lost as a consequence of dehydration. Both heart rate and body temperature are elevated during exercise when the skater is dehydrated more than 2% of body weight.

The impact of dehydration on the cardiovascular system is quite predictable. Plasma volume is lost and the ability to provide adequate blood flow to the skin and muscles is reduced. Under such circumstances, it is common for athletes to collapse, showing the usual symptoms of heat exhaustion. It is difficult to understand how some athletes tolerate several hours of hard skating in warm weather. In addition to the body water lost during endurance events, many nutrients are known to escape with sweat.

There are obvious benefits to drinking fluids during prolonged exercise, especially during hot weather . Drinking will minimize dehydration, lessen the rise in internal body temperature and reduce the stress placed on the circulatory system. Even warm fluids, near body temperature, provide some protection against overheating, but cold fluids seem to enhance body cooling. It takes some of the deep body heat to warm a cold drink to the temperature of the stomach and blood.

The fluid composition of the drink has an effect on the rate that it empties from the stomach. Since little exchange of water occurs directly from the stomach, the fluids must pass into the intestine before entering the blood. In the intestine, absorption is rapid and unaffected by exercise, provided that the activity does not exceed 75% of the skater's VO2 max. Many factors affect the rate at which the stomach will empty, including its volume, temperature, acidity and the number of particles it contains. Although large volumes of up to 20 ounces empty faster from the stomach than small portions, most athletes find it uncomfortable to exercise with a nearly full stomach, since this may interfere with breathing. Drinking small portions at 10 to 15 minute intervals tends to minimize this effect. Since there are wide individual variations in the rate of stomach emptying, the suggestions offered here are based on averages, and may not be appropriate for every skater. Each athlete must determine what combination works best.

Another factor known to regulate the rate at which the stomach empties is the number of dissolved substances in the solution (osmolality). The addition of electrolytes and other ingredients that raise osmolality slow the rate of water replacement. A number of 'sports drinks' containing electrolytes and carbohydrates are currently on the market, grossing more than $100 million each year. Unfortunately, many of the claims used to sell these drinks are based on misinterpreted and often inaccurate information. Since dehydration is the primary concern during hot weather skating, water seems to be the preferred fluid. It empties from the stomach with minimal delay, is easy to obtain and reduces the dehydration associated with heavy sweating. The obvious conclusions to be drawn are: water is a critical part of every athlete's diet, a well-hydrated athlete will perform better and no athlete can ever drink too much water.