Quotes from the news wire:
Our bodies love force, force is what helps our muscles get stronger ; force is what helps our bones to stay strong ; force is what helps or heart to stay strong by having to pump the blood against gravity. So, when you take that force away, you all of a sudden lose a really important stimulus that's important for health.
We have not flown people on long-duration missions with no exercise, we built our exercise suite as time has gone on. But, in the early Apollo missions, there was no exercise, and one of the things that came back from the Apollo astronauts is,' hey, you need to have some sort of exercise device on here.'.