Characterizing dynamic balance during adaptive locomotor learning.

Area of Science:

• Biomechanics
• Human locomotion
• Motor adaptation

Background:

• Split-belt treadmill walking is a common model for studying adaptation to asymmetric environments.
• Previous research suggests a desire to maintain dynamic balance may drive adaptation to symmetric walking patterns, but this remains uninvestigated.

Purpose of the Study:

• To investigate how dynamic balance is influenced by spatiotemporal asymmetry during split-belt treadmill walking.
• To explore the biomechanical strategies employed during adaptation to asymmetric walking environments.

Main Methods:

• A computational model based on a two-state exponential model was developed to simulate foot placement adjustments.
• An experiment involving participants walking on a split-belt treadmill (1.5 m/s left, 0.5 m/s right) was conducted.
• Lower extremity kinematics were measured using retroreflective markers to compute spatiotemporal metrics like step length and margins of stability.

Main Results:

• Participants exhibited greater margins of stability on the faster belt compared to the slower belt during adaptation.
• Adjustments in the leading limb angle were used to control foot placement relative to the body's center of mass.
• Times to contact were longer on the slow belt than the fast belt, with this difference diminishing over time.

Conclusions:

• The findings support the role of dynamic balance in driving adaptive changes in coordination during asymmetric walking.
• Experimental results align with the computational model, validating its predictive capabilities.
• This research enhances understanding of the biomechanical factors influencing adaptation to novel walking conditions.