Coordination between upper- and lower-limb movements is different during overground and treadmill walking

Area of Science:

• Biomechanics
• Human locomotion
• Motor control

Background:

• Locomotion studies frequently use treadmill (TW) and overground walking (OW) interchangeably.
• It is commonly assumed that differences in coordination between TW and OW are negligible.

Purpose of the Study:

• To investigate and compare the coordination between upper and lower limb movements in healthy individuals during OW and TW at matched speeds.
• To test the notion that differences between TW and OW are negligible.

Main Methods:

• Comparison of upper- and lower-limb movement coordination between healthy individuals during overground walking (OW) and treadmill walking (TW).
• Analysis of interlimb coordination, including frequency coupling and relative phase between arm and thigh motion.
• Assessment of cadence, sagittal shoulder acceleration, and arm-leg coordination patterns.

Main Results:

• Treadmill walking (TW) induced a higher cadence, influencing interlimb coordination (frequency coupling, relative phase).
• The 2:1 arm swing to stride pattern occurred less in TW, correlated with lower shoulder sagittal acceleration.
• TW showed a smaller relative phase between arm and ipsilateral thigh, linked to earlier thigh extension and shorter stance phase.

Conclusions:

• Arm-leg coordination differs significantly between overground walking (OW) and treadmill walking (TW).
• Differences are attributed to condition-specific adjustments in stride frequency scaling, dynamic axial posture control, and inter-limb synchrony.
• Recognizing distinct "motor sets" for TW and OW is crucial for interpreting physiological and patho-physiological locomotion studies.