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Prolonged exercise in highly trained female endurance runners
International Journal of Sports Medicine
|November 1, 1983
Summary
This study found that prolonged exercise in cool, dry conditions did not significantly alter key cardiorespiratory measures or blood markers in trained females. However, hematocrit, hemoglobin, and plasma osmolality did change, with notable pre-exercise plasma volume expansion.
Area of Science:
- Exercise Physiology
- Environmental Physiology
- Sports Science
Background:
- Understanding physiological responses to prolonged exercise in specific environmental conditions is crucial for athletes and researchers.
- Assessing cardiorespiratory and metabolic adaptations during sustained physical exertion informs training and performance strategies.
Purpose of the Study:
- To investigate the effects of prolonged exercise at 65%-70% VO2max in a cool, dry environment on physiological variables in highly trained females.
- To analyze changes in blood markers, hematological parameters, and cardiorespiratory responses during and after sustained exercise.
Main Methods:
- Seven highly trained females performed an incremental treadmill test to determine VO2max, followed by 80 minutes of exercise at 65% VO2max in a 21°C dry bulb/15°C wet bulb environment.
- Venous blood samples were collected pre- and post-exercise, with intermittent sampling during exercise, for analysis of glucose, lactate, osmolality, electrolytes, protein, and hemoglobin.
- Hematocrit was measured to calculate plasma volume changes, and cardiorespiratory variables (VO2, VE, RER, heart rate) were continuously monitored.
Main Results:
- No significant changes were observed in oxygen consumption (VO2), ventilation (VE), %VO2max, heart rate, venous lactate, plasma glucose, or plasma protein during prolonged exercise.
- A significant decrease in respiratory exchange ratio (RER) was noted.
- Significant alterations occurred in hematocrit, hemoglobin (Hb), plasma osmolality, Na+, and K+ levels, with a notable pre-exercise plasma volume expansion.
Conclusions:
- Prolonged exercise at moderate intensity in cool, dry conditions does not significantly impact cardiorespiratory function or key metabolic markers in trained females.
- Changes in hematological parameters and plasma osmolality suggest fluid shifts and electrolyte regulation occur during sustained exercise.
- The observed pre-exercise plasma volume expansion warrants further investigation regarding its implications for thermoregulation and performance.