Exposure to actual [1–3] or simulated [2, 4–7] microgravity reduces tolerance for physical exertion and alters cardiovascular responses to exercise in humans. Most [2, 4–6, 8], but not all [9] studies have shown impaired reflex responses to static exercise or cold pressor tests. However, the extent to which spaceflight or bedrest influences these reflexes, or whether other factors are responsible for the modulated reflex activity, remains unclear.