Effects of weightlessness in man.

The program for the Apollo 16 flight was designed to include both safeguards against and investigations of the physiological problems arising from increase in the period of manned space flight. Precautions included the provision of a controlled diet with high potassium content, carefully controlled work loads and work-rest cycles and an emergency cardiology consultation service, and investigations were made to enable pre-flight-post-flight comparisons of metabolic, cardiovascular and central nervous system data. Results of these investigations indicate that adjustment to weightlessness can be satisfactorily assisted by appropriate countermeasures including attention to diet.