Physiological and Functional Alterations after Spaceflight and Bed Rest.

Area of Science:

• Space physiology
• Human adaptation to spaceflight
• Sensorimotor function

Background:

• Spaceflight causes significant physiological deconditioning.
• Astronaut performance is critical for mission success.
• Understanding spaceflight's impact on function is vital.

Purpose of the Study:

• To assess spaceflight effects on astronaut functional task performance.
• To identify physiological factors causing performance deficits.
• To evaluate bed rest as a spaceflight analog.

Main Methods:

• Utilized a test battery of functional tests and physiological measures.
• Assessed sensorimotor, cardiovascular, and neuromuscular adaptations.
• Compared 6-month spaceflight with 70-day head-down bed rest (control and exercise groups).

Main Results:

• Spaceflight led to decrements in postural control and gait, mirroring sensorimotor deficits.
• Lower limb muscle performance decreased, and heart rate increased to maintain blood pressure.
• Exercise during bed rest preserved neuromuscular and cardiovascular function but did not prevent functional/balance deficits.

Conclusions:

• Body unloading during spaceflight contributes to postural control dysfunction.
• Exercise can maintain neuromuscular and cardiovascular health, aiding functional performance.
• A dedicated countermeasure is necessary to address postflight postural control deficits.