Exercise with and without gravitational gradient: evaluation with the new random access mass spectrometer (RAMS).

Area of Science:

• Cardiovascular Physiology
• Exercise Physiology
• Space Medicine

Background:

• Gravity increases arterial perfusion pressure to leg muscles in upright posture, affecting blood flow during exercise.
• Supine exercise demonstrates slower VO2 (volume of oxygen consumed) adaptation compared to upright exercise, attributed to altered perfusion gradients.
• Restoring the heart-to-leg perfusion gradient in supine subjects normalized VO2 adaptation, suggesting reduced skeletal muscle blood flow during supine exercise.

Purpose of the Study:

• To evaluate a new mass spectrometer system (GASMAP) for measuring cardiorespiratory responses.
• To assess cardiorespiratory adaptation to changing work rates under conditions challenging gravitational effects.
• To investigate exercise responses in microgravity, analogous to supine conditions.

Main Methods:

• Utilized sensitive breath-by-breath technology with a new mass spectrometer system.
• Challenged gravitational effects on cardiorespiratory response during exercise.
• Compared exercise responses in supine and upright postures, and simulated microgravity.

Main Results:

• Slower VO2 adaptation observed during supine exercise compared to upright exercise.
• Restoration of the perfusion gradient normalized VO2 adaptation in supine subjects.
• The new mass spectrometer system was evaluated under challenging gravitational conditions.

Conclusions:

• Altered perfusion gradients significantly impact cardiorespiratory adaptation during exercise.
• Exercise in microgravity is hypothesized to elicit responses similar to supine exercise.
• The GASMAP system is a viable tool for studying cardiorespiratory responses in altered gravity environments.