We find that passive arm movements (PAM) rhythmically performed in human subjects under the Achilles tendon vibration can induce non-voluntary step-like movements in ipsilateral leg. Our Aim was to study the influence of afferent information from the moving arm on the rhythmic activity in hip joint supposedly reflecting activity of central pattern generator. Method. Rhythmic activity in hip joint was estimated by the decrement of oscillation (HipDe cr) in Hip Release test (HR): The subject was placed on the left side with right arm and leg suspended. The right leg was extended by experimenter up to 20degrees backward to the craniacaudal line of body and released. PAM in shoulder, elbow and both joints were randomly performed at 2 frequencies, 2 amplitudes (100, 50deg.) and within 3 segments of the angular displacement. Vibration of the Achilles tendon (60Hz 1mm) was constantly applied during the experiment. Kinematics of the arm and leg joints was recorded by goniometric system in 9 healthy volunteers.

Results: 

In both, individual and group data HipDecr was smaller with PAM as compare to the same test without them (p=0,001). Biangular PAM show more influence than single-joint movements (p=0,033). Effect of PAM in shoulder and elbow joints statistically differed in 5 subjects with no common trend. ANOVA show no significant difference between the influences of PAM with high and low amplitude, frequency, speed and performed at different segments of the angular displacement.

Conclusion: 

the afferent information from the arms affects the rhythmic activity in the hip joint regardles the specific parameters of the arm movements. The data can reflect interact ion between central pattern generators of the legs and arms.