Hormonal, water balance, and electrolyte changes during sixty-day confinement

Area of Science:

• Space research
• Human physiology
• Psychological studies

Background:

• Performing both psychological and physiological protocols in a single study is challenging.
• Individual variability in physiological responses complicates space research and simulation studies.
• Confinement in isolation studies mirrors physiological changes seen in weightlessness simulations like bedrest.

Purpose of the Study:

• To clarify objectives for combined psychological and physiological studies.
• To understand the potentiation of physiological changes by confinement, workload, and stress.
• To identify and control for confinement effects in head-down bedrest simulations.

Main Methods:

• Utilized the EXEMSI and ISEMSI experiments for isolation studies.
• Introduced new techniques like the doubly labeled water method for total body water determination.
• Compared physiological data with psychological study results.

Main Results:

• Confinement, high workload, and stress were found to potentiate physiological changes observed in bedrest simulations.
• Confinement effects can manifest early in isolation (EXEMSI) or throughout (ISEMSI).
• Variations in experimental design (subject number, gender, living space, workload) led to unexpected or opposite effects compared to previous studies.

Conclusions:

• Clear definition of study objectives is crucial for successful combined psychological and physiological research.
• Standardized and well-examined operational scenarios are essential for future isolation studies.
• Physiologists must adapt to studying small groups, addressing individual differences and statistical challenges in space research.