Hydration status during activities in warm and humid weather can have a significant effect on the health of athletes and the quality of performance. Significant fluid and electrolyte losses due to sweat have been reported. For players participating in showcase soccer events, over a period of consecutive days, and at a mid-afternoon kickoff time, it is important to implement a hydration strategy that covers pre-match, intra-match, and post-match hydration in order to avoid thermal illness or other negative outcomes.
Body temperatures may increase by 2 degrees Celsius or more in the course of a soccer match on a hot, humid day (Williams, 2012). Evaporation of sweat is a method used by the body to regulate core temperature (Casa et al., 2000). Intense activities in a hot, humid environment can cause high rates of sweat in individuals resulting in a dehydrated state. “Dehydration of 1% to 2% of body weight begins to compromise physiologic function and negatively influence performance … [d]ehydration of 3% of body weight further disturbs physiologic function and increases an athlete’s risk of developing an exertional heat illness” (Casa et al, 2000, p. 212). If dehydration is sufficiently extreme, physical and mental performance may be degraded and the severity of degradation may be greater in higher temperatures and longer duration exercise (Maughan and Shirreffs, 2010). Loss of electrolytes within sweat has been observed, with sodium loss of particular note. “Sodium is the main electrolyte lost in sweat and the available data indicate considerable variability in sodium losses between players due to differences in sweating rate and sweat electrolyte concentration. (Sherriffs, Sawka, & Stone, 2006, p. 699). Individual hydration response can vary greatly based on a variety of attributes: sweat rate, fitness, acclimatization to heat, response to exercise, hydration status. (Lopez, 2012). In response, Lopez (2012) suggests an individualized approach to fluid replacement guidelines. Within these constraints, research has identified effective strategies for hydration before, during, and after exercise.
Hydration prior to competition has been indicated to support athletic performance. Research suggests that athletes often consume insufficient fluids prior to competition and are in a hypohydrated state (Mattausch, Domnik, Koehler, Schaenzer, & Braun, 2017). Athletes who begin activities in a hypohydrated state demonstrate impaired heat dissipation function during subsequent exercise (American College of Sports Medicine,1996). Casa et al. (2000) recommend that athletes should be hydrated prior to the beginning of exercises sessions, suggesting that “the athletes should consume approximately 500 to 600 mL (17 to 20 fl oz) of water or a sports drink 2 to 3 hours before exercise, and 200 to 300 mL (7 to 10 fl oz) of water or a sports drink 10 to 20 minutes before exercise.” (p. 213). Casa et al. (2000) also note that inclusion of carbohydrates (CHOs) and sodium chloride in the pre-competition hydration can increase glycogen storage and aid in acclimatization in the initial days of hot weather.
Hydration during the match is indicated in order to limit fluid and electrolyte loss. “During training and matches, limit body mass loss (due to sweat loss) to about 2% of body mass” (Shirreffs, Sawka, & Stone, 2006, p. 706). Some studies suggest drinking to thirst, but this may not always be practical and some athletes are not knowledgeable about their own fluid needs (Lopez, 2012). WIlliams (2012) recommends that athletes “[d]rink during stoppages of play, especially during half-time … drink a small amount (6-12 oz or 150-350 ml) every 15-20 min” (p. 62). American College of Sports Medicine (1996) advises athletes “to consume the maximal amount of fluids during exercise that can be tolerated without gastrointestinal discomfort up to a rate equal to that lost from sweating” (p. 13).
Post-match hydration is necessary to begin the recovery process and preparation for subsequent matches. WIlliams (2012) observes that rehydration “should begin quickly after the session or match, progress slowly and continue over the next 24 hours” (p. 63). Research supports the ingestion of CHO within a 30-60 minute window after a match to assist in glycogen resynthesis (Ranchordas et al., 2017; Williams, 2012c; Saunders, 2011). Consumption of fluids totaling 500 to 1000 mL within 30 minutes is indicated, with a sports beverage, or other beverage containing CHOs and electrolytes (Williams, 2012). Chocolate milk has been observed to provide an effective combination of protein and CHOs (Saunders, 2011). Spreading consumption over a period of 30-45 minutes has been recommended (Williams, 2012). As part of a post-game meal (3 or more hours post-match), additional fluids should be supplied to the athletes. “Since most fluid consumed by athletes is with meals, the presence of ample fluid during meals and adequate amount of time to eat are critical to rehydration” (Casa et al., 2000, p. 217).
A variety of drinks may be used to provide hydration support. The palatability, color, temperature, sweetness, flavor, presentation, and other factors may need to be tailored to individual taste in order to promote sufficient consumption. Shirreffs et al. (2004) note that “the volume consumed will be influenced by many factors, including the palatability of the drink and its effects on the thirst mechanism, although with a conscious effort some people can still drink large quantities of an unpalatable drink when they are not thirsty” (p. 58). Fluids should be cooler than air temperature, flavored for taste, readily available, and in packaging that allows for efficient consumption (American College of Sports Medicine,1996).
Not all consumable fluids are desirable for inclusion in pre-competition, match, or post-competition. Beverages that include fructose should be limited due to gastrointestinal discomfort (Casa et al., 2000). Caffeine and alcohol should be avoided due to potential increases in urine output while carbonated beverages should also be avoided due to possible reductions in voluntary fluid intake caused by stomach fullness (Casa et al., 2000).
References
American College of Sports Medicine. (1996). Position Stand-Exercise and fluid replacement. Med Sci Sports Exerc, 29, 11.
Casa, D. J., Armstrong, L. E., Hillman, S. K., Montain, S. J., Reiff, R. V., Rich, B. S., … & Stone, J. A. (2000). National Athletic Trainers’ Association position statement: fluid replacement for athletes. Journal of athletic training, 35(2), 212.
Lopez, R. M. (2012). Exercise and hydration: Individualizing fluid replacement guidelines. Strength & Conditioning Journal, 34(4), 49-54.
Mattausch, N. R., Domnik, K., Koehler, K., Schaenzer, W., & Braun, H. (2017). Case Study: Hydration Intervention Improves Pre-game Hydration Status in Female Collegiate Soccer Players. International journal of sport nutrition and exercise metabolism, 27(5), 475-481.
Maughan, R. J., & Shirreffs, S. M. (2010). Dehydration and rehydration in competative sport. Scandinavian journal of medicine & science in sports, 20, 40-47.
Ranchordas, M. K., Dawson, J. T., & Russell, M. (2017). Practical nutritional recovery strategies for elite soccer players when limited time separates repeated matches. Journal of the International Society of Sports Nutrition, 14(1), 35.
Saunders, M. J. (2011). Carbohydrate-protein intake and recovery from endurance exercise: Is chocolate milk the answer?. Current sports medicine reports, 10(4), 203-210.
Shirreffs, S. M. (2010). Hydration: special issues for playing football in warm and hot environments. Scandinavian journal of medicine & science in sports, 20, 90-94.
Shirreffs, S. M., Armstrong, L. E., & Cheuvront, S. N. (2004). Fluid and electrolyte needs for preparation and recovery from training and competition. Journal of sports sciences, 22(1), 57-63.
Shirreffs, S. M., Sawka, M. N., & Stone, M. (2006). Water and electrolyte needs for football training and match-play. Journal of sports sciences, 24(07), 699-707.
Williams, J.H. (2012). The importance of hydration. The Science Behind Soccer Nutrition, Chapter 6, pp 59-66.