Creatine is a naturally occurring chemical involved in the production of energy in muscle. Abnormalities in creatine have been linked to the progression of degenerative neuromuscular diseases such as amyotrophic lateral sclerosis (ALS, or Lou Gehrig's Disease). This study will test whether taking creatine can improve the symptoms of ALS.

Amyotrophic lateral sclerosis is a progressive neurodegenerative disorder selectively affecting motor neurons, resulting in progressive weakness. Currently there is no known cure and a specific cause has not been identified. Creatine is a nutritional supplement that improves mitochondrial function and has been shown to protect motor neurons in animal models of ALS. Preliminary research indicates that creatine may also improve strength in patients with ALS. This study will determine the effect of creatine treatment on short-term muscle strength and long-term muscle deterioration in patients with ALS.

Participants in this study will be randomly assigned to receive either creatine or placebo. Participants will be enrolled in the study for 9 months. Quantitative muscle testing will be done weekly for the first 3 weeks; participants will then be followed monthly for the next 4 months and bimonthly for the remainder of the 9-month study. The study will also monitor purposeful exercise to determine if this enhances the benefit of creatine usage on muscle strength. Pulmonary function testing will accompany the muscle testing to determine if creatine strengthens respiratory muscles, thereby enhancing pulmonary function.

Inclusion Criteria

• Diagnosis of probable or definite ALS
• At least 5 of 10 testable upper extremity muscle groups (shoulder and elbow extensors/flexors and grip) of Medical Research Council (MRC) grade 4 or better
• At least 5 years from onset of symptoms

Exclusion Criteria

• Requires tracheostomy ventilation
• History of renal disease