During this pilot study, the investigators will examine the effects of whole-body electrical muscle stimulation exercise (WB-EMS Exercise) on neuromuscular junction (NMJ) transmission and fatigability in adults with Generalized Myasthenia Gravis (gMG). The investigators will also test whether a relationship exists between NMJ transmission dysfunction and fatigability in gMG, which has long been presumed but never directly assessed. Participants will undergo clinical and electrophysiologic testing before and after the WB-EMS Exercise intervention. The WB-EMS Exercise intervention will be delivered 2 times per week for 4 weeks. Long-term follow up is optional. The hypotheses are (a) that the WB-EMS exercise will improve fatigability and NMJ transmission, and (b) that NMJ transmission dysfunction is related to fatigability.
Age 18 or older
Diagnosed with Generalized Myasthenia Gravis (gMG) via seropositive test for acetylcholine receptor (AChR) antibodies or seronegative test with clinical symptoms consistent with gMG
On stable MG therapy for at least 1 month
Ability to stand for approximately 15 minutes continuously with or without an assistive device (i.e. the length of time to stand to take a shower, complete meal preparation, wait in line at the bank, etc.)
Concurrent participation in another interventional research study
Unable to tolerate 15 minutes of continuous standing with or without an assistive device
Regular participation in strength training (2x per week or more over the past 6 months)
Score of 0 (None) on all "arm outstretched" and "leg outstretched" items of the QMG
Single group
Whole-body Electrical Muscle Stimulation Exercise
DeviceThis is a fitness device that delivers whole-body electrical muscle stimulation in conjunction with exercise programs using an iPad App. The stimulation suit (fitted shorts/shirt, vest, leg straps, arm straps) will be donned with the assistance of trained research personnel. Muscle groups stimulated include biceps, triceps, pectorals, abdominals, periscapular musculature, paraspinal musculature, gluteus musculature, quadriceps, and hamstrings. The stimulation level of each individual muscle group can be tailored to participant responses and tolerance (i.e. stimulation of the quadriceps and biceps can occur at different settings). While the participant is following along with the video, a qualified health care professional will be monitoring and adjusting the stimulation levels based on participant responses; rate of perceived exertion will also be monitored to ensure safe moderate intensity levels are maintained.
Mean change from baseline in single fiber electromyography (SFEMG) jitter
Single fiber electromyography (SFEMG) jitter is a measure of neuromuscular junction transmission variability; a small needle will be inserted into one of the quadriceps muscles to obtain the measurement
Mean change from baseline in the linear change in performance during the six-minute walk test (6MWT)
Six-minute Walk Test (6MWT) is a measure of endurance and muscle fatigability; participants will walk as far as they can in 6 minutes
Mean change from baseline in the linear change in performance during the arm movement test (AMT)
Arm Movement Test (AMT) is a measure of upper extremity muscle fatigability; participants will move their arm back and forth between 2 targets as many times as they can in 90 seconds
Mean change from baseline in the quantitative myasthenia gravis (QMG) score
Quantitative Myasthenia Gravis (QMG) is a measure of overall disease severity; items include eye movements, swallowing, speaking, breathing test, grip strength, and neck/arm/leg endurance. Thirteen items will be rated on a scale of 0-3 where higher scores indicated greater disease severity.
Mean change from baseline in motor unit firing rates of the vastus lateralis using decomposition electromyography (dEMG)
Decomposition electromyography (dEMG) is a measurement of motor unit activity; a surface electrode will be placed over the vastus lateralis in the thigh and participants will be asked to activate that muscle
Mean change from baseline in motor unit firing rates of the middle deltoid using decomposition electromyography (dEMG)
Decomposition electromyography (dEMG) is a measurement of motor unit activity; a surface electrode will be placed over the middle deltoid in the shoulder and participants will be asked to activate that muscle
Mean change from baseline in fatigue severity scale (FSS)
Fatigue Severity Scale (FSS) is a patient-reported outcome measure assessing the impact of perceived fatigue on a person's life over the prior 7-day period. Nine items are rated on a scale of 1-7 where higher scores indicate more impact of perceived fatigue.
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University of Missouri-Columbia
Lead sponsor
University of Kansas Medical Center
Collaborator
