| [ Summary ] |
Bone loss and muscle atrophy are essential problems for astronauts to overcome during space flight. The proximal femoral bone loses 1.5 percent of its mass per month. Bone loss rates during space flight deserves roughly ten times as rapidly than as observed in osteoporosis patients. During space flight and prolonged bed rest, the uncoupling of bone formation and bone resorption, as well as elevated bone resorption and lack of bone formation, leads to bone loss and renal stones. The combination of sufficient nutrition, exercise protocols, and medicines such as bisphosphonate reduces the risk of space flight induced bone loss and renal stones. The volume and strength of antigravity muscles declines more than voluntary muscles. Type I slow fibers experience greater loss than type II fibers. Muscle cross-sectional areas of the knee extensors and ankle flexors decline rapidly with prolonged bed rest. Muscle strength and volume decline conspicuously more than 60 years old. Space flight exercise countermeasure programs, which consist of aerobic and resistive training, reduce the risk of muscle atrophy and weakness in astronauts during space flight. Therefore those types of regimens may also help earth-bound patients. |