Genome and hormones: Gender differences in physiology - Invited review: Gender issues related to spaceflight: A NASA perspective

This minireview provides an overview of known and potential gender differen ces in physiological responses to spaceflight. The paper covers cardiovascu lar and exercise physiology, barophysiology and decompression sickness, ren al stone risk, immunology, neurovestibular and sensorimotor function, nutri tion, pharmacotherapeutics, and reproduction. Potential health and function al impacts associated with the various physiological changes during spacefl ight are discussed, and areas needing additional research are highlighted. Historically, studies of physiological responses to microgravity have not b een aimed at examining gender-specific differences in the astronaut populat ion. Insufficient data exist in most of the discipline areas at this time t o draw valid conclusions about gender-specific differences in astronauts, i n part due to the small ratio of women to men. The only astronaut health is sue for which a large enough data set exists to allow valid conclusions to be drawn about gender differences is orthostatic intolerance following shut tle missions, in which women have a significantly higher incidence of presy ncope during stand tests than do men. The most common observation across di sciplines is that individual differences in physiological responses within genders are usually as large as, or larger than, differences between gender s. Individual characteristics usually outweigh gender differences per se.