Cardiovascular responses to artificial gravity combined with exercise

Astronauts experience important physiological adaptation to weightless environment, including bone loss, muscle atrophy, cardiovascular deconditioning, and vestibular disorientation. Physiological deconditioning will be even more challenging in future long-duration space missions, for example to Mars, in which astronauts will be exposed to microgravity for six to eight months before landing without external help to support egress. Artificial gravity (AG) is a comprehensive countermeasure that could prevent physiological deconditioning during extended exposure to microgravity, particularly if it is combined with exercise. Here, we are investigating the effect of short-radius centrifugation combined with ergometer exercise on human physiology, particularly on the cardiovascular system. One subject is tested under three different levels of AG: 0g (no centrifugation), 1g, and 1.4 g (g levels measured at the feet). At each AG level, the subject completes a 25 min bicycle ergometry exercise protocol with three different exercise intensities: warm-up (25W), moderate (50W), and vigorous (100W). Continuous cardiovascular variables (heart rate, blood pressure, pulse pressure, stroke volume, cardiac output, and vascular resistance) are measured at heart level using a ccNexfin system (Edward Lifescience). Preliminary results show that the extent to which the cardiovascular system responds to artificial gravity depends on the gravity level being applied, suggesting that artificial gravity combined with exercise may be effective as a countermeasure against cardiovascular deconditioning in space.