The investigators seek to validate Slow Vital Capacity (SVC) measurement in seated and supine positions using conventional and portable spirometry.

SVC is obtained with in-clinic conventional spirometry, in-clinic portable spirometry, and in-home portable spirometry with respiratory therapist-supervised remote pulmonary function testing every two weeks in a six month prospective study of participants with a diagnosis of Amyotrophic Lateral Sclerosis. SVC decline over time, seated and supine, will be tracked with assessments for treatment changes.

Inclusion Criteria:

1. Diagnosis of ALS as Clinically Possible, Clinically Probable, Laboratory-supported Probable and Clinically Definite ALS
2. 18 years old to 100 years old, English-speaking ALS subjects, male and female

Exclusion Criteria:

1. Use of non-invasive ventilation more than 16 hours daily
2. Non-English Speaker
3. Psychosis or severe mental illness
4. Use of high-dose sedating psychotropic medications determined to potentially interfere with task performance
5. Infection Control issues and specific Pulmonary, Cardiac, Vascular contraindications as listed in the Standardization of Spirometry 2019 Update (Graham 2019)

Subjects are invited to volunteer and recruited from ALS specialty care outpatient clinics at SUNY Upstate and Atrium Health.

The plan is to share Individual Patient Data collected during the study to research team from both sites.

2 years.

Research team includes Principal investigators, sub-investigators, clinical research coordinators and respiratory therapists at each site, Pulmonologist Central Readers at SUNY Upstate. Deidentified data is shared with study sponsor MTPA.