This is the first part of a 2 part series on hydration and will focus on the need for adequate hydration and recognising dehydration in the young athlete.
The importance of adequate fluid intake in sports is to avoid dehydration and maintain normal heart function and thermoregulatory (ability of the body to deal with heat) responses. (1,2) If young athletes are fully hydrated before they start training, they will have a better chance of performing well. With inadequate hydration, they can suffer from early fatigue and the exercise will feel much harder than usual. Dehydration can also cause other symptoms such as headaches, nausea and dizziness. (3) Athletes from all sports should concentrate on optimal hydration. (2)
Endurance sports, e.g. running, cycling and swimming usually take place over a longer duration. The intensity of effort is usually sustained at a fairly constant submaximal intensity. When endurance training takes place in a hot and humid environment, the athlete can be predisposed to fluid and electrolyte loss. (2)
Strength and weight-class sports, e.g. judo and wrestling are characterized by repeated bouts of high intensity or maximal exercise typically lasting from a few seconds to 3 minutes. As with all athletes, it is important that athletes competing in strength and weight-class sports maintain adequate hydration. Dehydration can result in decreased performance and greater strain on the heart. Athletes competing in weight-class (wrestling and martial arts) and aesthetic sports (gymnastics and diving), often use dehydration to reduce body mass. This can increase the heat stress placed on the athlete, especially if working out in a heated room. It is important for young athletes to match their sweat losses with fluid intake and to avoid dehydration as a means to decrease body weight. (2)
Team sports are characterized by high-intensity, intermittent efforts that are repeated over the duration of the competitive event. These events can last between 30 to 90 minutes, depending on the sport and level of competition. The combination of the high intensity and repeated nature of the efforts require power, strength and endurance to obtain a high level of performance. Fluid intake is therefore crucial to prevent fatigue and maintain force production for power, speed and strength. (2)
KIDS ARE NOT YOUNG ADULTS – WHAT IS DIFFERENT?
The daily fluid turnover of adults has been estimated to be 2-3 litres per day and, although there is limited data on fluid needs of the child athlete, nonathletic children, aged 6-11 years, showed a daily fluid turnover of approximately 1.6 litres per day. Sweat loss during exercise in children can lead to an additional requirement of 0.5 to more than 1.0 litre per day. (1,2)
Compared to adults, children have less efficient thermoregulatory mechanisms. (4,3) Thermogenesis (generation of heat) per kilogram of body mass is greater in children than in adolescents and adults, but they do have a less effective ability to transfer heat from the centre of the body to the skin by blood. (4) Due to the greater body surface area to body volume ratio, children are also susceptible to a faster influx of heat when exercising in the heat. (1,2,4,5,6) Children have a lower sweat rate than adults, due to a less efficient sweat response. (1,2,3,4,5,6)
WHAT IS SCARY ABOUT DEHYDRATION?
A 1% decrease in body weight from exercise-induced sweating decreases endurance in children. Dehydration decreases performance through impairment of the cardiovascular system, thermoregulation, and general fatigue (perceived exertion). (2) Children and adolescents exercising in the heat should therefore be monitored closely for signs of heat stress, especially those with high levels of body fat and heavy builds. (4)
An easy way for young athletes to determine their hydration status is to evaluate the colour of their urine. Urine should be pale straw-coloured, not deep yellow and should not have a strong odour. Self-monitoring with the help of a urine colour chart can increase the awareness of hydration status. (3)
Early Symptoms of Dehydration
ACTION: Stop exercising and drink 100 – 200 ml water or sports drink every 10 – 15 minutes (3)
|Advanced Symptoms of Dehydration
ACTION: Stop exercising and drink 100 – 200 ml sports drink every 10 – 15 minutes. Seek professional help! (3)
EVEN MILD DEHYDRATION – A 2 % LOSS IN BODY WEIGHT – CAN IMPAIR PERFORMANCE, REDUCE STAMINA AND STRENGTH AND INCREASE FATIGUE. (3)
In part 2 of this series on hydration we will provide you with practical guidelines on adequate hydration, including what, how much and when to drink.
1. Nemet D & Eliakim A. (2009) Pediatric sports nutrition: an update. Current Opinion in Clinical Nutrition and Metabolic Care 12,304-309.
2. Petrie HJ, Stover EA & Horswill CA. (2004) Nutritional concerns for the child and adolescent competitor. Nutrition 20,620-631.
3. Bean A. (2010) Anita Bean’s Sport Nutrition for Young Athletes. A & C Black. London.
4. Bass S & Inge K. Nutrition for special populations: Children and young athletes in Bourke Clinical Sports Nutrition
5. Meyer F, O’Connor H & Shirreffs M. (2007) Nutrition for the young athlete. Journal of Sports Sciences 25 (S1), S73-S82.
6. Unnithan VB & Baxter-Jones ADG. (2000) The young athlete. In Nutrition in sport Volume VII of the encyclopaedia of sports medicine. (edited by Ronald J Maughan). 429-441. Blackwell Science Ltd. London.