Effect of spaceflight on the human body of muscle fibre prominent in muscles also change. Slow twitch endurance fibres used to maintain posture are replaced by fast twitch rapidly contracting fibres that are insufficient for any heavy labour. Advances in research on exercise, hormone supplements and medication may help maintain muscle and body mass. Bone metabolism also changes. Normally, bone is laid down in the direction of mechanical stress. However, in a microgravity environment there is very little mechanical stress. This results in a loss of bone tissue approximately 1.5% per month especially from the lower vertebrae, hip and femur. Due to microgravity and the decreased load
Pubis (bone) Pubis (bone) In vertebrates, the pubic bone is the ventral and anterior of the three principal bones composing either half of the pelvis. It is covered by a layer of fat, which is covered by the mons pubis. It is divisible into a body, a superior ramus and an inferior ramus. In the female, the pubic bone is anterior to the urethral sponge. The left and right hip bones join at the pubic symphysis. The pubis is the lower limit of the suprapubic region. The body forms one-fifth of the acetabulum, contributing by its external surface both to the lunate