The effect of electrical stimulation on leg muscle pump activity in spinal cord-injured and able-bodied individuals

Abstract

The purpose of this study was to examine the difference in: (1) effective muscle pump activity (MPA) between voluntary and electrically (ES) induced contractions in able-bodied subjects (ABS); and (2) ES-induced MPA between spinal cord-injured (SCI) individuals and ABS. MPA was measured as relative volume changes in the calf using strain-gauge plethysmography during repeated muscle contractions in the supine position while venous outflow was impeded by a thigh cuff inflated to a range of pressures. Ten SCI individuals and ten ABS participated in this study. ABS showed no significant difference between voluntary and electrically induced MPA [58.1 (18.4)% versus 67.7 (8.7)%, respectively]. SCI individuals showed a significantly lower ES-induced MPA than ABS [21.5 (15.9)% versus 67.7 (8.7)%, respectively]. The low MPA in SCI individuals may be explained by: (1) extensive leg muscle atrophy and/or (2) an "atrophic" vascular system in the legs. The electrical current level seemed to influence MPA (43 mA, 21.5% versus 60 mA, 30.8%) for SCI individuals, whereas no influence of muscle contraction rate on MPA was observed in ABS. The results of this study demonstrate that although ES-induced leg muscle contractions result in adequate MPA in ABS, it leads to significantly less effective MPA in SCI individuals.

Alternating stimulation of synergistic muscles during functional electrical stimulation cycling improves endurance in persons with spinal cord injury

“…Thus, the alternation protocol utilized in the current study may have required smaller stimulation intensity levels because the alternating activation history influenced the engagement of the tendon, which permitted each muscle to exert their tension without having to overcome all of the elastic damping. Force preservation from this stimulation strategy would also be heightened by the additional intermittent rest periods and to an increase in blood flow from enhanced muscle pump activity which increases during intermittent bouts of electrical stimulation delivered to paralyzed leg muscles (van Beekvelt et al, 2000). These postulates are consistent the results of other studies that have found alternating muscle activation strategies to reduce fatigue in non-paralyzed leg muscles (Tamaki et al, 1998;Sjogaard et al, 1986;Kouzaki et al, 2002Kouzaki et al, , 2003Shinohara and Kouzaki, 2006).…”

Energy expenditure during walking with weight-bearing control (WBC) orthosis in thoracic level of paraplegic patients

“…19 In addition, the isolation of the upright standing and walking should lead to various secondary disorders, for example, the decrement of the bone mineral density 20,21 and malfunction of the peripheral circulation in paralyzed areas. 22 Although there is little agreement of the effect on the above point, there is no doubt that some purposeful effects should be offered by orthotic gait. Previous studies have demonstrated that orthotic gait provides some benefits to the physical functions for paraplegic patients, such as the improvement of the urodynamics 8 and digestive functions.…”

Cardiovascular response to functional electrical stimulation and dynamic tilt table therapy to improve orthostatic tolerance

“…We have found that FES can reproduce functional movements, such as walking and grasping . In addition, several recent studies have investigated the use of FES to improve venous return in healthy (Faghri and Yount, 2002;Man et al, 2003;van Beekvelt et al, 2000) and SCI populations (Chao and Cheing, 2005;Faghri et al, 2001;Faghri and Yount, 2002;van Beekvelt et al, 2000). Alternatively, venous return can also be enhanced by exercise, since lengthening and shortening of muscle fibers will contribute to muscle pump activation (Laughlin, 1987).…”