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Changes in body composition in triathletes during an Ironman race
Sandro Manuel Mueller1, Elmar Anliker, Patrizia Knechtle
1Exercise Physiology, Institute of Human Movement Sciences, ETH Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
European Journal of Applied Physiology
|June 11, 2013
Summary
Triathletes lose significant lean mass and experience dehydration during an Ironman triathlon. This study used advanced imaging to precisely measure body composition changes, revealing muscle density decreases linked to glycogen depletion.
Area of Science:
- Sports Science
- Human Physiology
- Exercise Metabolism
Background:
- Ultra-endurance events like the Ironman triathlon cause significant physiological stress.
- Understanding body composition changes during such events is crucial for athlete performance and health.
- Previous studies lacked detailed segmental body composition analysis.
Purpose of the Study:
- To investigate Ironman-induced changes in segmental body composition.
- To utilize dual-energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT) for precise measurements.
- To provide novel insights into tissue catabolism during ultra-endurance exercise.
Main Methods:
- Eight non-professional male triathletes underwent DXA and pQCT scans before and after an Ironman triathlon.
- Segmental body composition and lower leg tissue characteristics were assessed.
- Hydration status was monitored via blood and urine sample analysis.
Main Results:
- A body mass loss of 1.9 ± 0.8 kg was observed, comprising 0.4 ± 0.3 kg fat mass and 1.4 ± 0.8 kg lean mass.
- Calf muscle density decreased by 1.93 ± 1.04 %, indicating potential glycogen loss.
- Increased plasma [Na(+)], urine specific gravity, and osmolality suggested dehydration.
Conclusions:
- Lean mass loss is attributed to decreased muscle density (glycogen depletion) and dehydration.
- DXA and pQCT provided accurate quantification of fat and lean mass loss.
- The study offers detailed insights into tissue catabolism during ultra-endurance exercise.
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