Skylab 2 crew observations and summary
Signs and symptoms experienced during weightlessness ranged from a sensation of fullness in the head to a strange body posture and the sensation of fluid drainage out of the legs. There was no vestibular sense of the upright whatsoever unless the crewmember happened to look at the earth; motion sickness was not a clinical problem. The ability to maintain physical fitness through exercise and the caloric demand remained just about the same as they do on the ground after initial adjustment.
Kerwin, J. P.↗