A Phase 3, Open-Label Extension of COURAGE-ALS (CY 5031)

Inclusion Criteria: * Able to comprehend and willing to sign an ICF and willing to comply with all study procedures and restrictions for the duration specified in the Schedule of Activities. If non-written consent is given, a Legal Designee of the patient must sign the ICF form. * Completed dosing in CY 5031 Exclusion Criteria: * Has taken investigational study drug (other than reldesemtiv) prior to dosing, within 30 days or five half-lives of the prior agent, whichever is greater * Presence on Day 1 of any medically significant cardiac, pulmonary, gastrointestinal, musculoskeletal, or psychiatric illness that might interfere with the patient's ability to comply with study procedures or that might confound the interpretation of clinical safety or efficacy data. * Use of a strong cytochrome P450 (CYP) 3A4 inhibitor within 7 days prior to first dose of reldesemtiv in CY 5032 or a strong CYP3A4 inducer within 14 days prior to first dose of reldesemtiv in CY 5032 * Use of a medication that is an OCT1/OCT2 substrate within 7 days prior to first dose of reldesemtiv in CY 5032 * Currently participating in another trial, managed access program, open label extension, early access program, or through the right to try act is receiving an investigational drug or received an investigational drug or device within 30 days (or 5 half-lives for drugs, whichever is longer) prior to Day 1. Patients also cannot be taking outside of a clinical trial certain investigational drugs (which includes drugs, supplements, and nutraceuticals) that are currently being studied or have been studied for the treatment of ALS.