REACTION OF THE CARDIOVASCULAR, SYSTEM TO ORTHOSTATIC TESTING DURING EXTENDED HEAD-DOWN BED REST AS A FUNCTION OF THE...

Area of Science:

• Cardiovascular Physiology
• Space Medicine
• Human Physiology

Background:

• The cardiovascular system (CVS) is susceptible to reduced physical activity, posing risks both on Earth and in space.
• Head-down bed rest (BR) is a common model for simulating microgravity effects on the human body.

Purpose of the Study:

• To investigate the mechanical cardiac responses to a standing test during prolonged head-down bed rest.
• To evaluate how the timing of initiating countermeasures affects cardiovascular adaptation during bed rest.

Main Methods:

• Utilized electrocardiography (ECG) and echocardiography (echoECG) to assess cardiac bioelectrical and mechanical activity.
• Conducted standing tests at baseline, every 60 days during bed rest, and on day 60 of recovery.

Main Results:

• Cardiovascular function exhibited a nonlinear response over time during bed rest.
• Orthostatic stability and recovery time were significantly influenced by the extent of countermeasures applied during bed rest.

Conclusions:

• The timing and scope of countermeasures are critical for mitigating cardiovascular deconditioning during bed rest.
• Early implementation of countermeasures is essential for maintaining cardiovascular regulation and promoting faster recovery.