Increase of total body water with decrease of body mass while running 100 km nonstop--formation of edema?

Area of Science:

• Sports Science
• Human Physiology
• Endurance Sports

Background:

• Ultraendurance running events like 100-km races pose significant physiological challenges.
• Understanding body mass changes and hydration status is crucial for athlete performance and health.

Purpose of the Study:

• To investigate changes in body mass, fat mass, skeletal muscle mass, and total body water in male ultraendurance runners.
• To assess hydration status using urinary and hematological parameters during a 100-km run.

Main Methods:

• Anthropometric measurements for body mass, fat mass, and skeletal muscle mass.
• Bioelectrical impedance analysis for total body water.
• Urinary specific gravity (USG) and hematological parameters (hematocrit, plasma sodium) for hydration status.

Main Results:

• Body mass decreased by 1.6 kg, fat mass by 0.4 kg, and skeletal muscle mass by 0.7 kg.
• Total body water increased by 0.8 L, indicating potential overhydration.
• Hematocrit and plasma sodium decreased, while plasma urea and USG increased, suggesting minimal dehydration.

Conclusions:

• Ultraendurance running leads to significant loss of lean body mass and fat mass.
• Runners experienced a complex hydration state, with evidence of both overhydration and dehydration.
• Body mass changes were associated with alterations in total body water during the race.