Determining An Appropriate Cardiopulmonary Exercise Testing Protocol For Individuals With Neuromuscular Disease

Abstract

PURPOSE: To review published standards and recommendations for people with neuromuscular disease and establish a graded ramp-up protocol to assess exercise tolerance for individuals who have moderate to severe muscle weakness. METHODS: A review of literature for muscular dystrophy or neuromuscular disease and exercise testing was performed to assess different methodologies in Cardiopulmonary Exercise Testing (CPET) using cycle ergometry CPET. A progressive ramp-up protocol was developed and administered with patients who attend Stanford’s multidisciplinary clinic to determine feasibility and test termination criteria that may limit the ability to achieve maximum oxygen consumption. RESULTS: Literature search resulted in 43 research studies. The study breakdown included Myopathies and McArdle disease =20; Pompe=5; FSHD; SMA, Metabolic Myopathies=3; DMD/BMD=2, Myotonic Dystrophy=2; CMT=1; IBM=1. Studies greatly ranged in mode of testing. Most study participants were ambulatory. Most protocols used a graded 1-2 minute progressive ramping protocol up to the point of exhaustion indicated by a Visual Analog Scale and heart rate. Early termination resulted from participants voluntarily stopping due to muscle weakness. We developed a progressive ramp up protocol with 1-minute increment increase in workload at 5-watt intervals to avoid early termination from large increases in workload. We tested 3 individuals with neuromuscular disease and 2 controls. Only 2 participants (1 with NMD and 1 control) were able to reach an RER of 1.1 of maximal oxygen uptake (VO2max). Reasons for early termination were consistent with the published literature including heart rate, voluntary stop and muscle weakness. CONCLUSIONS: With promising treatments on the horizon for neuromuscular diseases, physical therapists are asked to determine appropriate exercise prescriptions for individuals with a range of functional abilities and muscle weakness. Currently, CPET protocol methodology varies for weaker individuals. Our results will contribute to developing a proposed submaximal clinical exercise tolerance test protocol to establish safe exercise prescriptions and determine treatment intervention benefits for patients with neuromuscular disease.