The human body is suited for condit

The human body is suited for conditions under Earth's gravity. Therefore,
if the force of gravity increases or decreases, the body feels a distinct,
unfamiliar sensation. It causes a decrease in heartbeat; muscles
become weaker and bones lose calcium. Engineers and medical doctors
have investigated how humans can survive long periods where there is
little gravity without causing the body to atrophy. Orbiting
laboratories have been built to experiment with zero gravity on Earth.