Interappendicular Neurological Coupling During Various Locomotor Tasks In Persons With Spinal Cord Injury

Abstract

It has been suggested that neurological coordination between the upper and lower limbs during human locomotion is accomplished largely via subcortical centers, but the functional implications of spinal limb coupling during walking have not been fully explored. However, emerging evidence exists showing that active arm movements during locomotion can augment leg muscle activity in persons with paralysis. PURPOSE: To determine the influence of upper limb actions on muscle activity during various locomotor tasks in persons with spinal cord injury (SCI). METHODS: Six (n = 5 male, 1 female) persons (31 ± 8 yr, 69.2 ± 9.3 kg, 1.78 ± 0.09 m) with SCI (4 cervical & 2 thoracic injuries) were suspended above a treadmill via a body weight support (BWS) system which allowed for partial loading of the lower body (45% body weight). Therapists located on the side of the treadmill manually moved their legs through the gait pattern at a set cadence (85 steps/min) while the treadmill moved at 1.6 mi/hr. During body weight support treadmill training (BWSTT) participants swung their arms (Swing), held parallel bars located on the side of the treadmill (Hold) and held in a similar yet unsupported position as in the parallel bar condition (Sham). Plantar forces (Pf) and surface electromyography (sEMG) of six lower limb muscles was measured and averaged for 12 steps during each of the upper body conditions. RESULTS: Maximal sEMG of the medial gastrocnemius was significantly greater (p=.04) in Swing (18.4 ± 13.1) compared to Hold (12.9 ± 15.9) just before initial contact, when mechanical loading of the legs was not different. No other sEMG measures used for statistical analysis yielded significant differences, but case comparison of participants indicates that differences in individual responses could be largely explained by injury characteristics. CONCLUSION: Results suggest that active arm movement during locomotion could augment leg muscle activity in persons with SCI, and that the influence of arm actions differs based on neurological level and extent of injury. Therefore, in persons with paralysis the actions of the arms during walking should be considered in both rehabilitation and community contexts.