There is a great need for the development of sensitive outcomes that allow experimental drugs to be tested in human subjects more efficiently. If we could more precisely measure whether an experimental drug slows the progression of ALS or other neuromuscular diseases, this would allow more drugs to be tested quicker and at less expense. We have developed a new device that accurately measures isometric strength called: Accurate Test of Limb Isometric Strength (ATLIS). This device was designed to be portable, quick, and easy to use, while generating accurate and reliable, interval level data. This study will enable us to test the reliability and validity of ATLIS.

Inclusion Criteria:

• All subjects must be at least 18 years old and able to provide informed consent
• All subjects have no health conditions that limit their ability to safely exert maximal force using the muscles in their arms and legs.
• Subjects with a diagnosis of laboratory supported probable, probable or definite ALS according to the World Federation of Neurology El Escorial, as determined by their referring neurologist at MGH.
• All subjects must be able to speak and understand English.

Exclusion Criteria:

• Presence of significant arthritis, orthopedic conditions, or cardio-pulmonary conditions or other medical conditions that may limit the ability to maximally exert force safely.

Individuals with ALS