Karen A. Sharwood

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To evaluate the role of fluid and Na+ balance in the development of exercise-associated hyponatremia (EAH), changes in serum Na+ concentrations ([Na+]) and in body weight were analyzed in 2,135 athletes in endurance events. Eighty-nine percent of athletes completed these events either euhydrated (39%) or with weight loss (50%) and with normal (80%) or(More)
OBJECTIVES To determine the prevalence of overweight and obesity in a sample of South African children aged 6 - 13 years. DESIGN Random sampling of schools within each provincial and socio-economic category. SETTING Primary school children from 5 South African provinces. SUBJECTS 10 195 (5 611 male and 4 584 female) primary school children. OUTCOME(More)
AIMS Assessment of the left ventricular responses to prolonged exercise has been limited by technology available to assess cardiac tissue movement. Recently developed strain and strain rate imaging provide the unique opportunity to assess tissue deformation in all planes of motion. METHODS AND RESULTS Nineteen runners (mean+/-SD age; 41+/-9 years) were(More)
This study investigated the effects of the neuromuscular and force–velocity characteristics in distance running performance and running economy. Eighteen well-trained male distance runners performed five different tests: 20 m maximal sprint, running economy at the velocity of 4.28 m s−1, 5 km time trial, maximal anaerobic running test (MART), and a(More)
BACKGROUND Subjects exercising without fluid ingestion in desert heat terminated exercise when the total loss in body weight exceeded 7%. It is not known if athletes competing in cooler conditions with free access to fluid terminate exercise at similar levels of weight loss. OBJECTIVES To determine any associations between percentage weight losses during(More)
OBJECTIVE To establish relationships between body weight changes and serum sodium during and after an Ironman Triathlon, and postrace fluid status and rectal temperature, including the incidence of hyponatremia. DESIGN Descriptive research. SETTING The 2000 South African Ironman Triathlon, in which each athlete swam 3.8 km, cycled 180 km, and ran 42.2(More)
CONTEXT Critical assessment of recommendations that athletes consume additional sodium during athletic events. OBJECTIVE To evaluate if sodium supplementation is necessary to maintain serum sodium concentrations during prolonged endurance activity and prevent the development of hyponatraemia. DESIGN Prospective randomised trial of athletes receiving(More)
OBJECTIVE To examine the relationship between body weight, plasma volume, and serum sodium concentration ([Na]) during prolonged endurance exercise. DESIGN Observational field study. SETTINGS 2000 South African Ironman Triathlon. PARTICIPANTS 181 male triathletes competing in an Ironman triathlon. MAIN OUTCOME MEASURES Body weight, plasma volume,(More)
OBJECTIVE The objective of this study was to determine whether sodium supplementation 1) influences changes in body weight, serum sodium [Na], and plasma volume (PV), and 2) prevents hyponatremia in Ironman triathletes. SETTING The study was carried out at the South African Ironman triathlon. PARTICIPANTS Thirty-eight athletes competing in the triathlon(More)
Of 371 athletes (62% of all finishers) whose weights were measured before and after the 226 km South African Ironman Triathlon, the athlete who gained the most weight (3.6 kg) during the race was the only competitor to develop symptomatic hyponatraemia. During recovery, he excreted an excess of 4.6 litres of urine. This case report again confirms that(More)