[Interlimb interactions during cyclic in-phase and antiphased movements of arms and legs and their dependence on afferent influences].

Coordinated movements of arms and legs suppose the neural interaction between the generators of the rhythmics of the upper and lower extremities. In the lying position in 10 healthy subjects activity of the muscles of the upper and lower extremities was recorded when separate and joint cyclic movements of the arms and legs with different phase relationships between the movements of the limbs were performed, and under various conditions of the motor task. Antiphased active arm movements were characterized by increased muscle activity than during in-phase mode. The activity of the arm muscles under passive movements, imposed by experimenter, was significantly less than their activity when passive movements of the arms were imposed by the other arm. When loading one arm the muscle activity in the other passively moving arm increased independently from the synergy of arm movements. During motor tasks, implementing joint antiphased movements as the upper and lower extremities, compared to motor task, implementing their joint in-phase movements, there has been a significant increase in activity in the biceps brahii muscle, the tibialis anterior muscle and biceps femoris muscle. Loading of arms in these motor tasks has been accompanied by increased activity in some of the leg muscles. Increasing of frequency of rhythmic movements resulted in a significant growth of the muscle activity of the arms and legs with their cooperative movements with greater rate of rise of flexor muscles activity for arms and legs during joint antiphased movements. Thus, the spatial organization of movements and kind of afferent influences are significant factors of interlimb interaction, which, in turn, determine the type of neural interconnections that are involved in the regulation of movements.

[Abnormalities in mutual influences of upper and lower limbs in patients with stroke].

Previously, in healthy subjects the common pattern of muscle activation and specifics of interlimb neuron connections during performance of rhythmic separate and simultaneous movements of arms and legs in the lying position, which reflect functional meaningful of interlimb interactions, were shown. The aim of this research was to investigate such mutual influences of upper and lower limbs during the execution of similar motor tasks by patients with stroke. In sixteen poststroke patients with different stage of hemiparesis arms movements together with or without legs movements were performed, while lying supine. It was demonstrated that the common pattern of muscle activity distribution under the execution of voluntary cyclic movements by both arms was disordered. Passive rhythmic movements of each arm caused the phased EMG activity in shoulder muscles in patients with mild hemiparesis, but no activation was observed in patients with severe paresis. The loading of nonparetic arm resulted in an increasing of activity in shoulder flexor muscles of paretic arm in patients with weak paresis (which was typical for healthy subjects), while it not exerted essential influences in patients with severe paresis. Under connecting the cyclic movements of arms with stepping movements of legs in diagonal synergy the activity in proximal muscles of both arms was decreased irrespective of the paresis degree, as it was seeing in healthy subjects. Simultaneous arms and legs movements did not change the muscle activity in non-paretic leg in both groups of patients, but in some muscles of paretic leg the activity even decreased. The results obtained revealed important features of poststroke motor disturbances, which caused the changes of interlimb interaction and in great degree depended on the level of paresis. The data of investigation can be of a great importance for developing the new methods for rehabilitative procedure in patients with stroke.

[Mutual influences of upper and lower extrimities during cyclic movements].

The possibility of muscle activation of passive arm during its cyclic movements, imposed by active movements of contralateral arm or by experimenter was studied, as well as the influence of lower extremities cyclic movements onto arm muscles activity. In addition to that the activity of legs muscles was estimated in dependence on motor task condition for arms. Ten healthy supine subjects carried out opposite movements of arms with and without stepping-like movements of both legs. The experiment included three conditions for arm movements: 1) the active movements of both arms; 2) the active movements of one arm, when other entirely passive arm participated in the movement by force; 3) passive arm movement caused by experimenter. In the condition 2) additional load on active arm was applied (30 N and 60 N). In all three conditions the experiment was carried out with arms movements only or together with legs movements. The capability of passive moving arm muscles activation depended on increasing afferent inflow from muscles of contralateral arm was demonstrated. Emerging electrical activity was modulated in the arms movements cycle and depended on the degree of active arm loading. During combined active movements of arms and legs the reduction of activity in the flexor muscles of shoulder and forearm was observed. Concomitant arms movements increased the magnitude ofelectromiographic bursts during passive stepping-like movements in the most of recorded muscles, and the same increasing was only observed in biceps femoris and tibialis anterior muscles during active legs movement. The increasing of loading of one arm caused essential augmentation of EMG-activity in the majority of recording legs muscles. The data obtained are the additional proof of existence of functionally significant neuronal interaction both between arms and between upper and lower extremities, which is evidently depend on the intraspinal neuronal connections.