The first questions asked by patients with a new diagnosis of Amyotrophic Lateral Sclerosis (ALS) often include: "Does exercise help slow the progression of the disease?", "Is there any harm in exercising?", or "What type of exercise (endurance or resistance) is most appropriate?" At this time, however, there is a lack of answers for people who suffer from an illness that affects their strength above all else. Yet the beneficial effects of exercise in both healthy people as well as people with other diseases have been extensively studied and resulted in recommendations about the types of exercise that are beneficial. In this study the investigators will ask participants with ALS to exercise in one of three ways: weightlifting (resistance exercise), stationary bicycling (endurance exercise), and range of motion exercise (the current "standard of care" for ALS patients). The investigators will use several different types of tests to determine whether one type of exercise is tolerated better and is safer than another. The investigators will also collect information about how the body responds to exercise in ALS. This study will help in the development of a larger national study to understand how exercise can be combined with other treatments to potentially improve strength and alter the course of the disease.

Inclusion Criteria:

1. Participants with familial or sporadic ALS diagnosed as possible, laboratory-supported probable, probable, or definite according to the WFN El Escorial criteria
2. Participants who are ages 18-80, inclusive.
3. Slow Vital Capacity (SVC) must be equal to or greater than 70% of predicted value
4. ALSFRS-R score >30.
5. Patients who are currently on any medications must be on a stable dose for the past 30 days.
6. Participants must provide informed consent prior to completion of any study procedures.

Exclusion Criteria:

1. Participants who are already performing >30 min. of endurance exercise/day for ≥ 3x/week (Borg scale-- "hard" or "somewhat hard") within 30 days of screening.

2. Participants who are already performing resistance exercise ≥ 3x/week within 30 days of screening.

3. Neurologic

   • Participants with history of ALS symptoms over 5 years duration
   • Inability to obtain consent (psychiatric or dementing illness)
   • History of neuromuscular dysfunction not related to ALS

4. Cardiac

   • Patents with clinically significant ECG abnormalities
   • Uncontrolled hypertension (SBP>160 or DBP>110)
   • Recent history of angina (within the last 2 years)
   • Recent history of abnormal stress test (within the last 2 years)
   • Symptomatic severe aortic stenosis
   • Active endocarditis
   • Symptomatic heart failure

5. Respiratory

   • Subjects with a history of respiratory dysfunction not related to ALS (i.e. COPD)

6. General

   • Subjects with chronic infectious disease including HIV, hepatitis B or C.
   • History of substance abuse within the past year
   • Patients who have a history of poor compliance to medical regimens or study requirements.
   • Uncontrolled diabetes
   • Recent embolism (within the last 6 months)
   • Severe orthopedic conditions that would prohibit exercise

7. Pregnancy

   • Female subjects who are pregnant or planning to become pregnant.
   • Female subjects of childbearing potential who are not practicing contraception.