Date of Degree
PhD (Doctor of Philosophy)
Physical Rehabilitation Science
Richard K. Shields
The loss of physical activity after a spinal cord injury results in musculoskeletal deterioration and metabolic dysfunction. Rehabilitation often overlooks the importance of physical activity in the paralyzed limbs for systemic metabolic health. There is a need for safe, feasible exercise interventions to increase physical activity levels in the paralyzed limbs of people with chronic paralysis that have severe musculoskeletal loss. The goal of this work is to 1) develop a gene expression signature after a single dose and long term training using a high force exercise in people with an acute spinal cord injury; 2) develop a novel low force exercise intervention using electrical muscle stimulation to limit force production and increase routine physical activity for chronically paralyzed human skeletal muscle; 3) determine the gene expression signature after a single dose of this novel low force exercise in people with long term paralysis; 4) develop a dose estimate of this low force exercise needed to initiate a phenotype transformation of chronically paralyzed skeletal muscle.
The major findings of this research are 1) a single dose of high force exercise increases the expression of key regulatory genes needed for the transformation of paralyzed skeletal muscle observed after long term training; 2) our novel low force exercise intervention challenges chronically paralyzed muscle but not non-paralyzed muscle; 3) a single dose of low force exercise increases the expression of key regulatory genes needed to improve skeletal muscle health; 4) a dose of at least 4 days per week of our low force exercise is needed to initiate a phenotype transformation of chronically paralyzed skeletal muscle. Together, this work supports the use of a low force exercise intervention for people with long term spinal cord injury and establish the need for future work assessing effects of our low force exercise on the systemic health and quality of life of people with long term spinal cord injury.
Routine physical activity promotes health and reduces the risk of developing some chronic diseases. People with a spinal cord injury are unable to move their paralyzed limbs. Consequently, muscle and underlying bone begin to deteriorate. Muscle has an important role regulating blood sugar levels. The loss of muscle after a spinal cord injury impairs the body’s ability to regulate blood sugar, contributing to the development of chronic diseases like type 2 diabetes. The goal of this research was to develop a safe, feasible, and efficacious exercise intervention using neuromuscular electrical stimulation for with a spinal cord injury. We developed a novel low-force exercise using neuromuscular electrical stimulation to evoke muscle contractions in people with long-term paralysis. We tested the local effect of our low-force exercise on one limb of people with paralysis while keeping the other limb as a control. Our low-force exercise challenged paralyzed muscle and initiated key changes in gene expression needed to restore muscle’s ability to contribute to blood sugar regulation. The effect of our low-force exercise was maximized when performed for 90-minutes at least 5 times per week. Together, these results regarding local skeletal muscle changes support the use of a low-force exercise in people with chronic spinal cord injury. Future studies using multiple muscle groups are needed to determine how low-force exercise influences the health, quality of life, and blood sugar regulation of people with long-term spinal cord injury.
publicabstract, electrical muscle stimulation, gene expression, skeletal muscle, spinal cord injury
Copyright 2016 Michael Arlyn Petrie