Paradigms of Lower Extremity Electrical Stimulation Training After Spinal Cord Injury

Summary

Spinal cord injury is a traumatic medical condition that may result in elevated risks of chronic secondary metabolic disorders. Here, we presented a protocol using surface neuromuscular electrical stimulation-resistance training in conjunction with functional electrical stimulation-lower extremities cycling as a strategy to ameliorate several of these medical problems.

Abstract

Skeletal muscle atrophy, increased adiposity and reduced physical activity are key changes observed after spinal cord injury (SCI) and are associated with numerous cardiometabolic health consequences. These changes are likely to increase the risk of developing chronic secondary conditions and impact the quality of life in persons with SCI. Surface neuromuscular electrical stimulation evoked resistance training (NMES-RT) was developed as a strategy to attenuate the process of skeletal muscle atrophy, decrease ectopic adiposity, improve insulin sensitivity and enhance mitochondrial capacity. However, NMES-RT is limited to only a single muscle group. Involving multiple muscle groups of the lower extremities may maximize the health benefits of training. Functional electrical stimulation-lower extremity cycling (FES-LEC) allows for the activation of 6 muscle groups, which is likely to evoke greater metabolic and cardiovascular adaptation. Appropriate knowledge of the stimulation parameters is key to maximizing the outcomes of electrical stimulation training in persons with SCI. Adopting strategies for long-term use of NMES-RT and FES-LEC during rehabilitation may maintain the integrity of the musculoskeletal system, a pre-requisite for clinical trials aiming to restore walking after injury. The current manuscript presents a combined protocol using NMES-RT prior to FES-LEC. We hypothesize that muscles conditioned for 12 weeks prior to cycling will be capable of generating greater power, cycle against higher resistance and result in greater adaptation in persons with SCI.

Introduction

It is estimated that approximately 282,000 persons in the U.S. are currently living with spinal cord injury (SCI)¹. On average, there are roughly 17,000 new cases annually, primarily caused by motor vehicle crashes, acts of violence, and sporting activities¹. SCI results in partial or total interruption of neural transmission across and below the level of injury², leading to sub-lesional sensory and/or motor loss. After injury, activity of skeletal muscle below the level of injury is greatly reduced, leading to a rapid decline in lean mass and concomitant infiltration of ectopic adipose tissue, or....

Protocol

The training protocol described in this manuscript is registered with clinicaltrials.gov identifier (NCT01652040). The training program involves NMES-RT with ankle weights and FES-LEC. All necessary equipment is listed in Table 2. The study protocol and informed consent were reviewed and approved by the Richmond VAMC Institutional Review Board (IRB) and Virginia Commonwealth University (VCU) IRB. All study procedures were explained in-detail to each participant before beginning the trial.

1. Participant Recruitment

1. Perform a pre-screening evaluation with potential participants.
   1. Thoroughly explain the....

Results

Ankle weights increased progressively for 22 participants, over 16 weeks of NMES-RT (Figure 6a). The average weights lifted by the participants was 19.6 ± 6.5 lb. (right leg) and 20 ± 6 lbs. (left leg) [8-24 lb.]. Current amplitude fluctuated throughout the trial for right and left legs (Figure 6b).

Progression of an individual with motor complete SCI following 12 weeks.......

Discussion

The current study demonstrated two different paradigms of electrical stimulation. One paradigm is focused on implementing progressive loading to the trained muscle to evoke skeletal muscle hypertrophy and the other paradigm is primarily intended to enhance cardio-metabolic performance via enhancing aerobic capacity. The study ensured to compare both paradigms and to highlight the pros and cons of each.

NMES-RT is proven to be effective in restoring muscle size and evoking hypertrophy in person.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
adhesive carbon electrodes (2 of each)	Physio Tech (Richmond, VA, USA 23233)	PT3X5 PALS3X4 E7300	7.5' x 12.7' 7.5' x 10' 5' x 9'
TheraTouch 4.7 stimulator	Richmar (Chattanooga, TN, USA 37406)	400-082	41.28' x 39.37' x 17.78' (8.91 kg) power: 110 VAC at 60 Hz / 220VAC at 50 Hz power consumption: 110 Watts
Red & White Lead Cords (2)	Richmar (Chattanooga, TN, USA 37406)	A1717	2.0 m
RT300-SL FES Ergometer	Restorative Therapies, Inc. (Baltimore, MD, USA 21231)	RT300-SL	80' x 49' x 92-103' (39 kg) 16 channel speed: 15 – 55 rev/min
elastic NuStim wraps (2)	Fabrifoam (Exton, PA, USA 19341)	PP108666	36"
wooden wheelchair break (2)	n/a	n/a	n/a
pillow/cushion	n/a	n/a	standard
ankle weights	n/a	n/a	2-26 lb.