**3.11 Effects of artificial gravity**

We tested an intermittent short-arm centrifuge of 1.4 G with 60-W ergometric exercise with a step-up increase of 0.2 G and 15 W, respectively, for 30 min every day for 21 days during −6° head-down bedrest [33]. The circulatory blood volume was reduced by 20% in the control subjects, but no reduction was observed in the countermeasure subjects. Cardiac output and stroke volume were not changed in the countermeasure subjects, but they decreased in the control subjects. The baseline level of muscle sympathetic nerve activity (MSNA) was not changed in the countermeasure subjects, but it increased in the control subjects.

Therefore, everyday ergometric exercise under artificial gravity maintains the preflight cardiovascular state without adapting to microgravity.
