not be counted among good fluid replacement choices as both caffeine and alcohol increase water loss from the body. Throughout the recovery periods of the

day and week, fluids from any non-caffeine or alcohol containing beverage and watery foods such as soups, fruits, and vegetables contribute significantly to fluid replacement and water balance.

KEEPING WATER LOSS IN CHECK As noted above, the simplest way to determine whether an athlete is drinking enough before and during activity to maintain water balance is to weigh them before and after each workout. That way the amount of fluid needed to reset blood volume can be determined on a daily basis. An alternative method or a way to check whether an athlete’s fluid replacement efforts have been successful is to monitor urine colour and/ or volume. (see Table 1). The urine of a fully hydrated person should be pale yellow (provided he or she is not taking vitamins or medications that effect urine colour). Urine volume can also be monitored but this is a bit more cumbersome. Urine volume should be about 1.5 litres per day.

A NOTE ABOUT HYPERHYDRATION Hyponatremia, or low body sodium concentration, is very dangerous and can cause collapse and even death. Generally it is caused by overconsumption of fluids, particularly water, and amateur endurance athletes or first time long distance racers are more at risk because they are often encouraged to drink “as much as possible” to prevent dehydration. However racing long distances at a more modest pace it is possible to replace more fluids than are being lost, thereby diluting the salt concentration in the blood. A better approach for these participants is to drink ad libitum (as influenced by thirst) at a rate of no more than 400 to 800 ml/hour (10).

THE BOTTOM LINE Staying on top of hydration before, during, and after workouts is an important aspect of maximising training and performance potential. Because sweating rates and fluid and electrolyte losses vary with individuals, environmental conditions, intensity of training and customised fluid replacement programmes are recommended. (11) The recommendations outlined here will help athletes, coaches and trainers to determine the fluid replacement programme appropriate to each person.

SHOULD NOT BE COUNTED AMONG GOOD FLUID REPLACEMENT CHOICES AS BOTH CAFFEINE AND ALCOHOL INCREASE WATER LOSS FROM THE BODY

References 1. Judelson DA, Maresh CM, Anderson JM, Armstrong LE, Casa DJ, Kraemer WJ, Volek JS. Hydration and muscular performance: does fluid balance affect strength, power, and high intensity endurance? Sports Medicine 2007;37:907-21 2. McGregor S, Nicholas C, Lakomy H, Williams C. The influence of intermittent high-intensity shuttle running and fluid ingestion on the performance of a soccer skill. Journal of Sports Science 1999;17: 895-903 3. Devlin LH, Fraser SF, Barras NS, Hawley JA. Moderate levels of hypohydration impairs bowling accuracy but not bowling velocity in skilled cricket players. Journal of Science and Medicine in Sport 2001;4:179-87

4. Shirreffs SM, Merson SJ, Fraser SM, Archer DT. The effects of fluid restriction on hydration status and subjective feelings in man. British Journal of Nutrition 2004;91:951-8 5. Shirreffs SM. The importance of good hydration for work and exercise performance. Nutritional Revue 2005;63:S14-S21

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THE AUTHOR

Dr Amy Lanou, PhD, is assistant professor of health and wellness for the University of North Carolina-Asheville (UNCA). She also serves as senior nutrition scientist for the Physicians Committee for Responsible Medicine (PCRM), a Washington DC-based nonprofit organisation dedicated to

promoting preventive medicine, especially better nutrition, and higher standards in research. Dr Lanou is the author of Healthy Eating for Life for Children (John Wiley and Sons, Feb 2002) and numerous research articles and opinion pieces on nutrition and disease prevention. Dr Lanou received her BSc in Nutrition Science from the University of California at Davis and her PhD in Human Nutrition from Cornell University.

ALCOHOL AND CAFFEINE CONTAINING BEVERAGES MAY BE ENJOYED IN MODERATION BY ADULT ATHLETES BUT

6. Manz F. Hydration and disease. Journal of the American College of Nutrition 2007;26:535S-41S 7. Pivarnik JM. Water and electrolytes during exercise. In Nutrition in Exercise and Sport. Hickson JF, Wolinsky I, eds. CRC Press, 1989:185- 200 8. Wendt D, van Loon LJ, Lichenbelt WD. Thermoregulation during exercise in the heat: strategies for maintaining health and performance. Sports Medicine 2007;37:669-82 9. Ganio MS, Casa DJ, Armstrong LE, Maresh CM. Evidence-based approach to lingering hydration questions. Clinical Journal of Sports Medicine 2007;26:1-16 10. Noakes T, IMMDA. Fluid replacement during marathon running. Clinical Journal of Sports Medicine 2003;13:309-18 11. Am College of Sports Medicine, Sawka MN, Burke LM, Eichner ER, Maughan RJ, Montain SJ, Stachenfeld NS. American College of Sports Medicine position stand. Exercise and fluid replacement. Medicine and Science in Sports and Exercise 2007;39:377-90

TABLE 1: HYDRATION CHART The lower the number, the better the result. A urine colour rating of 1, 2 or 3 is considered to be well-hydrated. Based on these results, changes in fluid intake can be made. Precautions: Certain medicines and vitamins may cause the colour of the urine to change. If any of these have been taken, this test is unreliable. The colours you see on the screen, or when you print the image out, may appear different to the original chart. Therefore this chart should only be used as a guide. If more accurate comparison is required, please go to an original source.

From Armstrong, LE. Performing in Extreme Environments, Human Kinetics 2000.

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