Male Ironman Triathletes Lose Skeletal Muscle Mass

鐵人三項男選手流失骨骼肌質量

10.6133/apjcn.2010.19.1.12

Beat Knechtle；Barbara Baumann；Andrea Wirth；Patrizia Knechtle；Thomas Rosemann

體脂肪 ； 身體質量 ； 脫水 ； 超耐力 ； 鐵人三項 ； body fat ； body mass ； dehydration ； ultra-endurance ； triathlon

Asia Pacific Journal of Clinical Nutrition

19卷1期（2010 / 03 / 01）

91 - 97

英文

We investigated whether male triathletes in an Ironman triathlon lose body mass in the form of fat mass or skeletal muscle mass in a field study at the Ironman Switzerland in 27 male Caucasian non-professional Ironman triathletes. Pre- and post-race body mass, fat mass and skeletal muscle mass were determined. In addition, total body water, hematological and urinary parameters were measured in order to quantify hydration status. Body mass decreased by 1.8 kg (p＜0.05), skeletal muscle decreased by 1.0 kg (p＜0.05) whereas fat mass showed no changes. Urinary specific gravity, plasma urea and plasma volume increased (p＜0.05). Pre- to post-race change (Δ) in body mass was not associated with Δ skeletal muscle mass. Additionally, there was no association between Δ plasma urea and Δ skeletal muscle mass; Δ plasma volume was not associated with Δ total body water (p＞0.05). We concluded that male triathletes in an Ironman triathlon lose 1.8 kg of body mass and 1 kg of skeletal muscle mass, presumably due to a depletion of intramyocellular stored glycogen and lipids.

We investigated whether male triathletes in an Ironman triathlon lose body mass in the form of fat mass or skeletal muscle mass in a field study at the Ironman Switzerland in 27 male Caucasian non-professional Ironman triathletes. Pre- and post-race body mass, fat mass and skeletal muscle mass were determined. In addition, total body water, hematological and urinary parameters were measured in order to quantify hydration status. Body mass decreased by 1.8 kg (p＜0.05), skeletal muscle decreased by 1.0 kg (p＜0.05) whereas fat mass showed no changes. Urinary specific gravity, plasma urea and plasma volume increased (p＜0.05). Pre- to post-race change (Δ) in body mass was not associated with Δ skeletal muscle mass. Additionally, there was no association between Δ plasma urea and Δ skeletal muscle mass; Δ plasma volume was not associated with Δ total body water (p＞0.05). We concluded that male triathletes in an Ironman triathlon lose 1.8 kg of body mass and 1 kg of skeletal muscle mass, presumably due to a depletion of intramyocellular stored glycogen and lipids.