Hydration knowledge and practices of long distance runners in the South African National Defence Force

[摘要] English: Endurance exercise has recently become more popular, but requires optimal hydration toensure peak performance. The human body regulates fluid homeostasis as long as food andfluids are available. As soon as an athlete starts to train, muscle exertion and environmentalfactors challenge the ability of the human body to regulate fluid homeostasis. A weight loss ofmore than two percent during exercise has been linked to changes in haemorheology,metabolic dysregulation, heat intolerance, cardiovascular strain, and the subsequent inabilityto maintain exercise workload. In this study the hydration knowledge and practices of longdistance runners in the South African National Defence Force was determined in relation tocurrent hydration recommendations. The study followed a descriptive, observational design,using a self-reporting questionnaire and anthropometric measurements as data collectiontechniques.Of the 144 participants included in the study, the majority was black (40.5%) males (80.5%),mostly from the Western Cape (47.7%), who works as operators (51.9%). Participants had amean age of 40 (±8.636 SD) years. According to the body mass index (BMI), four (3.2%)participants were underweight, 36.0% overweight/obese and 60.8% had a normal weigh, withno significant difference between the mean BMI of half and full marathon (p=0.0601). Withmore than a third of athletes being overweight/obese, athletes need to be informed regardingthe health implications of being overweight or obese, as well as the impact of overweight andobesity during endurance exercise on performance.Reported race experience, ranged between 13 and 365 months. A mean weight loss of 0.002kg (±0.404 SD) was recorded between registration and pre-race, with the largest weight lossbeing 0.8 kg and the most weight gained 3.5 kg. Nearly half (42%, n=55) of participants forwhom body weight was measured before and after the race lost 2% or more of their bodyweight during the race. A maximum weight loss of 4.2 kg was measured during the race, whichequalled a body weight loss of 6.36%. This put the athletes at risk for serious health risks andimplicates that athletes need to be educated regarding the dangers of fluid losses duringactivity. With regard to hydration knowledge, 66.0% of participants obtain hydration knowledge mainlyfrom reading books and magazines and 94 (65.3%) participants indicated that they read labels on sports drinks, focussing mostly on carbohydrate level. Athletes need to be counselled tofocus on electrolyte levels as well. Although the majority (73.8%) of participants knew that fluidinfluences performance, 20 (13.9%) were not able to indicate why weight loss occurs duringmarathon participation and 38.9% were uncertain whether urine colour influences physicalperformance. Although most participants had a reasonable good general knowledge regardinghydration, training is needed in important areas such as the effect fluid have on performanceand how to assess hydration status using urine colour and weight change during training andcompetitions. Alarmingly 11.1% of participants were not able to report symptoms ofdehydration, which is important to prevent heat-related illnesses. Athletes should be able toidentify dehydration as well as over hydration early, understand the implications, and beequipped to restore hydration status in order to optimize performance.With regard to hydration practices nine participants (6.3%) indicated that they do not consumeextra fluids before, during or after a race, which is a cause for concern considering the healthrisks associated with dehydration. Athletes need to be aware of the implication of notconsuming sufficient amounts of fluids when participating in endurance events. Fourty onepercent participants consumed extra fluids at least four hours before the race. For athletesparticipating in the half marathon, mean fluid intake was significantly higher than for the fullmarathon. There was however no significant difference in fluid intake per kilogram body weightbetween the half; and full marathon. Participants preferred energy drinks (32.6%) before arace and water during (28.5%) and after (21.5%) a race. Most participants (78.5%) relied solelyon fluids provided by the race organisers and few (13.2%) carried fluids with them. The amountof fluid consumed depended mostly on environmental conditions (71.1%), with only 13.6%participants consuming more fluids due to dehydration cues. Most participants (61.8%)reported to drink according to thirst rather than to maintain weight or according to scheduleand more than half (54.8%) reported that they never dehydrate during a race. More attentionshould be given to educate runners on how to monitor hydration status, emphasizing that thirstis not the only hydration cue and is not sufficient to prevent dehydration. Athletes should betaught how to use different techniques to assess hydration status and need to learn how todevelop an appropriate individualized rehydration strategy comprising the amount as well astime of fluid intake.

[发布机构] University of the Free State