The Sweating Response of Elite Professional Soccer Players to Training in the Heat

Abstract

Sweat rate and sweat composition vary extensively between individuals, and quantification of these losses has a role to play in the individualisation of a hydration strategy to optimise training and competitive performance. Data were collected from 26 male professional football (soccer) players during one 90 min pre-season training session. This was the 2nd training session of the day, carried out between 19.30 and 21.00 h when the mean ± SD environment was 32 ± 3 °C, 20 ± 5 %rh and WBGT 22 ± 2 °C. Training consisted of interval running and 6-a-side games during which the average heart rate was 136 ± 7 bpm with a maximum rate of 178 ± 7 bpm (n = 19). Before and after training all players were weighed nude. During training all players had free access to sports drinks (Gatorade®) and mineral water (Solan de Cabras®). All drink bottles were weighed before and after training. Players were instructed to drink only from their own bottles and not to spit out any drink. No player urinated during the training session. Sweat was collected by patches from the chest, arm, back, and thigh of a subgroup of 7 players. These remained in place for the first 15 - 30 min of the training session, and sweat was analysed for sodium (Na⁺) and potassium (K⁺) concentration. Body mass loss was 1.23 ± 0.50 kg (ranging from 0.50 to 2.55 kg), equivalent to dehydration of 1.59 ± 0.61 % of pre-training body mass. The sweat volume lost was 2193 ± 365 ml (1672 to 3138 ml), but only 972 ± 335 ml (239 to 1724 ml) of fluid was consumed. 45 ± 16 % of the sweat volume loss was replaced, but this ranged from 9 % to 73 %. The Na⁺ concentration of the subgroup's sweat was 30.2 ± 18.8 mmol/l (15.5 to 66.3 mmol/l) and Na⁺ losses averaged 67 ± 37 mmol (26 to 129 mmol). The K⁺ concentration of the sweat was 3.58 ± 0.56 mmol/l (2.96 to 4.50 mmol/l) and K⁺ losses averaged 8 ± 2 mmol (5 to 12 mmol). The drinking employed by these players meant that only 23 ± 21 % of the sweat Na⁺ losses were replaced: This ranged from replacing virtually none (when water was the only drink) to replacing 62 % when the sports drink was consumed. These elite soccer players did not drink sufficient volume to replace their sweat loss. This, however, is in accord with data in the literature from other levels of soccer players and athletes in other events. These measurements allow for an individualisation of the club's hydration strategy.

Drinking - hydration - soccer - sweat rate - sweat composition

References

• 1 American College of Sports Medicine . Position stand on exercise and fluid replacement.  Med Sci Sports Exerc. 1996;  28 i-vii
• 2 Armstrong L E, Costill D L, Fink W J. Influence of diuretic-induced dehydration on competitive running performance.  Med Sci Sports Exerc. 1985;  17 456-461
• 3 Bangsbo J. The Physiology of Soccer - With Special Reference to Intense Intermittent Exercise. Copenhagen; University of Copenhagen 1993
• 4 Bangsbo J. Energy demands in competitive soccer.  J Sports Sci. 1994;  12 5-12
• 5 Broad E M, Burke L M, Cox G R, Heeley P, Riley M. Body weight changes and voluntary fluid intakes during training and competition sessions in team sports.  Int J Sport Nutr. 1996;  6 307-320
• 6 Burke L M, Hawley J A. Fluid balance in team sports: Guidelines for optimal practices.  Sports Med. 1997;  24 38-54
• 7 Coyle E F, Gonzalez-Alonso J. Cardiovascular drift during prolonged exercise: new perspectives.  Exerc Sport Sci Rev. 2001;  29 88-92
• 8 Devlin L H, Fraser S F, Barras N F, Hawley J H. Moderate levels of hypohydration impair bowling accuracy but not bowling velocity in skilled cricket players.  J Sci Med Sport. 2001;  4 179-187
• 9 Eichner E R. Treatment of suspected heat illness.  Int J Sports Med. 1998;  19 150-153
• 10 Ekblom B. Applied physiology of soccer.  Sports Med. 1986;  3 50-60
• 11 Flear C TG, Gill C V, Burn J. Beer drinking and hyponatraemia.  Lancet. 1981;  2 477
• 12 Gonzalez-Alonso J, Teller C, Andersen S L, Jensen F B, Hyldig T, Nielsen B. Influence of body temperature on the development of fatigue during prolonged exercise in the heat.  J Appl Physiol. 1999;  86 1032-1039
• 13 Gopinathan P M, Pichan G, Sharma V N. Role of dehydration in heat stress-induced variations in mental performance.  Arch Environ Health. 1988;  43 15-17
• 14 Jonnalagadda S S, Rosenbloom C A, Skinner R. Dietary practices, attitudes and physiological status of collegiate freshman football players.  J Strength Condit Res. 2001;  15 507-513
• 15 Kirkendall D T. Effects of nutrition on performance in soccer.  Med Sci Sports Exerc. 1993;  25 1370-1374
• 16 Leatt P. The Effect of Glucose Polymer Ingestion on Skeletal Muscle Glycogen Depletion During Soccer Match Play and its Resynthesis Following a Match. University of Toronto; MSc Thesis 1986
• 17 Leiper J B, Broad N P, Maughan R J. The effect of intermittent high intensity exercise on gastric emptying in man.  Med Sci Sports Exerc. 2001;  33 1270-1278
• 18 Leiper J B, Prentice A S, Wrightson C, Maughan R J. Gastric emptying of a carbohydrate-electrolyte drink during a soccer match.  Med Sci Sports Exerc. 2001;  33 1932-1938
• 19 McGregor S J, Nicholas C W, Lakomy H KA, Williams C. The influence of intermittent high-intensity shuttle running and fluid ingestion on the performance of a soccer skill.  J Sports Sci. 1997;  17 895-903
• 20 Maughan R J. Effects of CHO-electrolyte solution on prolonged exercise. Lamb DR, Williams MH Perspectives in Exercise Science and Sports Medicine. Carmel; Benchmark Press 1992: 35-85
• 21 Maughan R J. Water and electrolyte loss and replacement in exercise. Maughan RJ Nutrition in Sport. Oxford; Blackwell 2000: 226-240
• 22 Maughan R J, Leiper L B. Fluid replacement requirements in soccer.  J Sports Sci. 1994;  12 29-34
• 23 Maughan R J, Shirreffs S M. Fluid and electrolyte loss and replacement in exercise. Harries M, Williams C, Stanish WD, Micheli LL Oxford Textbook of Sports Medicine. 2nd Ed. New York; Oxford University Press 1998: 97-113
• 24 Maughan R J, Leiper J B, Shirreffs S M. Fluids and electrolytes during exercise. Garrett WE Textbook of Sports Medicine. Baltimore; Williams and Wilkins 2000: 413-424
• 25 Mohr M, Krustrup P, Bangsbo J. Match performance of high-standard soccer players with special reference to development of fatigue.  J Sports Sci. 2003;  21 519-528
• 26 Mustafa K Y, Mahmoud N EA. Evaporative water loss in African soccer players.  J Sports Med Phys Fitn. 1979;  19 181-183
• 27 Nielsen B, Kubica R, Bonnesen A, Rasmussen I, Stoklosa J, Wilk B. Physical work capacity after dehydration and hypethermia: a comparison of the effect of exercise versus passive heating and sauna and diuretic dehydration.  Scand J Sports Sci. 1981;  3 2-10
• 28 Noakes T D, Goodwin N, Rayner B L, Branken T, Taylor R KN. Water intoxication: a possible complication during endurance exercise.  Med Sci Sports Exerc. 1985;  17 370-375
• 29 Reilly T. Football. Reilly T, Secher N, Snell P, Williams C Physiology of Sports. London; E and FN Spon 1990: 371-426
• 30 Shephard R J. Biology and medicine of soccer: An update.  J Sport Sci. 1999;  17 757-786
• 31 Shirreffs S M, Maughan R J. Whole body sweat collection in man: an improved method with some preliminary data on electrolyte content.  J Appl Physiol. 1997;  82 336-371
• 32 Smodlaka V J. Cardiovascular aspects of soccer.  The Physician and Sportsmedicine. 1978;  18 66-70
• 33 Solera A, Salazar W. Influence of dehydration and rehydration on basketball free throw accuracy.  Med Sci Sports Exerc. 2003;  35s 29