Human Locomotion Strategies Under Changed Bodyweight Support

Area of Science:

• Biomechanics
• Human Physiology
• Robotics and Space Exploration

Background:

• Understanding human musculoskeletal system energy expenditure is crucial for various applications, including space exploration and rehabilitation.
• Previous research has explored biomechanics of locomotion, but detailed analysis of energy costs under simulated reduced gravity is limited.

Purpose of the Study:

• To analyze the energy costs of the human musculoskeletal system during normal walking and walking under reduced body weight loading.
• To investigate biomechanical parameters and joint kinetic energy changes under simulated Martian and lunar gravity conditions.

Main Methods:

• Fifteen subjects walked on a treadmill at 90 steps/min under three loading conditions: 100% (Earth), 38% (Mars), and 17% (Moon) body weight.
• Recorded joint angles and angular velocities of the hip, knee, and ankle.
• Analyzed joint phase trajectories and the ratio of kinetic extension to flexion energy.

Main Results:

• Significant changes in kinetic energy parameters were observed in the foot joints under varying loads.
• In hip joints, flexion kinetic energy decreased from 90% (100% body weight) to 9% (17% body weight).
• The ratio of flexion and extension energy in the ankle joint equalized under reduced loading, with 38% body weight being sufficient for approximation.

Conclusions:

• Reduced body weight loading shifts phase trajectories toward smaller joint angles and decreases the ratio of extension to flexion kinetic energy in the knee.
• Observed changes in joint energy dynamics provide insights into locomotion under different gravitational conditions.
• The proposed assessment methods can be applied in clinical practice for evaluating rehabilitation effectiveness in patients with musculoskeletal disorders.