Influence of Arm Joint Limitation on Interlimb Coordination during Split-belt Treadmill Walking
Keisuke Hirata, Hiroki Hanawa, Taku Miyazawa, Takanori Kokubun, Keisuke Kubota, Moeka Sonoo, Naohiko Kanemura
Vol. 8 (2019) p.130-136
During walking, arm and leg swings in healthy people are closely coupled temporally by interlimb coordination. A split-belt treadmill contains two belts that can be driven at different velocities, and is used to demonstrate the adaptability of human bipedal locomotion. Previous studies focusing on the use of split-belt treadmills in patients with neurological disorder demonstrated the existence of impaired temporal limb coordination in such patients, but the influences of neural and nonneural factors on interlimb coordination could not be examined separately. Further, the influence of limiting one joint of an arm on temporal coupling was unclear. The purpose of this study was to clarify the influences of limiting one arm joint and the corresponding compensation by the unlimited arm. Ten healthy young adults walked on a double-belt treadmill equipped with force sensors, during a tied-belt period (velocity of both belts = 0.9 m/s, 3 min) followed by a split-belt period (belt velocities = 0.9 m/s and 1.8 m/s, 6 min). The following experimental conditions were studied: slow side restrained, fast side restrained, and unrestrained (NR). A non-flexible bandage-type restraint limited the elbow extension to 20°. The correlations between the trajectories of arm and leg swings were analyzed using a Vicon motion capture system. The correlation coefficients between the restraint arm swing and slow- or fast-side leg swing were significantly lower in the restraint conditions compared to other condition in both tied-belt and split-belt periods. In particular, the anti-phase swing of the ipsilateral arm and leg and the in-phase swing of the contralateral arm and leg decreased. These results suggest that elbow limitation inhibits interlimb temporal coordination. The unrestrained arm swing increased in spatial amplitude, but maintained higher temporal coupling with the leg. Non-neural factors are expected to cause reduction of interlimb coordination in individuals having neurological disorders and joint limitations.