How did they simulate zero gravity and its adverse effects on the human body??
This has already been done years ago. You can simulate the influence of microgravity http://en.wikipedia.org/wiki/Weightlessness#Microgravity on the cardiovascular system and the skeleton using so called head down bed rest. The idea is if you are laying down at a down tilt of e.g. 5 degrees and are not allowed to stand up or sit up during the experiment you can simulate both the influence on the cardiovascular system and the unloading of the bones.
In the late 1980ies a 370-day-long head down tilt bed rest experiment was carried out in the Soviet Union, which is the bed rest study of the longest duration yet. This study showed that it was possible to counteract the immobilization induced bone loss by doing 1-2 hours of exercise per day combined with treatment with a pharmaceutical (a bisphosphonate, which is part of a group of agents that is currently used for treating/preventing osteoporosis [http://en.wikipedia.org/wiki/Bisphosphonate]). A control group who did not do any countermeasures experienced a significant loss of bone mass after 120 days of bed rest, after which they also stated the same exercise regimen as the other participants and seemed to regain some of the lost bone.
(For reasons that is not clear to me this study was not published and the samples were put on storage unanalyzed until we got access to them. We analyzed the bone samples and published them with the original investigators from Russia and France.)