Lower limb kinematics during treadmill walking after space flight: implications for gaze stabilization

Area of Science:

• Biomechanics
• Space Physiology

Background:

• Spaceflight alters musculoskeletal function.
• Understanding lower limb joint kinematics post-flight is crucial for astronaut health and performance.

Purpose of the Study:

• To analyze changes in lower limb joint kinematics during treadmill walking after spaceflight.
• To assess the impact of microgravity adaptation on gait variability and stability.

Main Methods:

• Kinematic data collected during pre- and postflight treadmill walking from seven astronauts.
• Analysis of gait cycle phase-plane variability and joint-specific events (heel strike, toe off).
• Evaluation of lower limb joint system stability using a dedicated index.

Main Results:

• No significant changes in basic gait temporal characteristics (stride time, duty cycle).
• Increased postflight phase-plane variability in lower limb joints, notably knee at heel strike and hip at toe off.
• Overall lower limb joint system stability remained unchanged postflight.

Conclusions:

• Spaceflight leads to joint-dependent increases in gait variability, particularly at key locomotor events.
• Despite increased variability, overall lower limb stability is maintained.
• Observed kinematic changes may have implications for head and gaze control, potentially linked to altered musculoskeletal energy attenuation.