Maintenance of Plasma Volume and Serum Sodium Concentration Despite Body Weight Loss in Ironman Triathletes

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