Sex differences in human physiology pelvis is, in general, different between the human female and male skeleton. It differs both in overall shape and structure. The female pelvis, adapted for gestation and childbirth, is less high, but proportionately wider and more circular than in the male; its sacrum—the triangular bone at the upper posterior of the pelvic cavity, serving as base of the spine—is also wider. The female pelvis is tilted anteriorly, often resulting in the more sway-backed appearance. In the female, the acetabula, the concave surfaces to which the balls of the femurs attach via ligaments, are located farther apart, which increases the distance
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