- Other significant medical conditions, including the following: chronic or recurrent respiratory, gastrointestinal, neuromuscular, neurological, or psychiatric conditions; musculoskeletal problems interfering with exercise; autoimmune or collagen vascular diseases; immunodeficiency diseases or a positive HIV test; malignancies within 5 years of study entry, with the exception of skin cancer that is therapeutically controlled; endocrine and metabolic disorders; or any other medical condition or disease that is life-threatening or that may interfere with or be aggravated by exercise