John E. Greenleaf

John E. Greenleaf

John E. Greenleaf, former research physiologist at the NASA Ames Research Center near Stanford University, is interviewed in September 2007 in this segment of “Living History of Physiology” by Donald Watenpaugh, Ph.D. Dr. Greenleaf established and directed the Laboratory for Human Environmental Physiology in the Life Sciences Division at the research center. Over his 40-year career, he has had 181 published research articles, 127 abstracts, 23 book chapters, 75 other publications and numerous awards.

Dr. Greenleaf says the driving force of his career was a chemistry teacher he had in high school. He was frustrated with projects that did not work at school, so he created his own chemistry laboratory in his basement, trying the experiments at home instead. His early college career at the University of Illinois led him on the path toward physical education, and once he got to his PhD oral exams, he decided it was time to switch his minor, physiology, to his new major. The physiology department was more of a biological department, however, so his human research design and interest came from the physical education background. He says the combination of the two majors was ideal.

His first publication was a single-authored letter to Nature, and it is what he calls an ancillary observation about the PhD work he did at Illinois. It focused on exercising people for eight hours at 120 degrees of ambient temperature and exercising those who are dehydrated or previously dehydrated. The study showed there was a relation between exercise training and the level of heat acclimation, meaning if you are in a high level of aerobic work capacity then you can handle the heat better. Dr. Greenleaf was also among the first to study involuntary dehydration, which is when somebody who is dehydrated or is being dehydrated is offered liquid, and they only consume half and say they have had enough. There is always a little dehydration left over, and he says a lot of animals are not that way, including horses, dogs and camels. If animals get dehydrated, they will drink exactly what they need.

Dr. Greenleaf started at Ames in 1963. He says his most challenging project there were the bed rest studies he worked on. He and others wrote and published 12 articles on the subject. He also discussed peer-review, and whether he prefers blind review or non-blind review. He said that if the reviewers know the authors, then the authors ought to know the reviewers, which might prevent reviewers from making certain comments that were harsh and unnecessarily critical.

He said in 1965, he believed that women were going to follow men into space, so he proposed doing some research on women. They performed exercise tests under extreme heat and with dehydration, and wrote up a publication on it. He and others had to leave to go to Stockholm for a one-year postdoctoral position, so he handed it in and left town. When he returned, colleagues informed him of the uproar his publication had caused, using reasoning that if research was being done on women, then they would soon have to be allowed to become astronauts. It was the first paper in NASA to use women as subjects, and after the publication, the ball was rolling to help women become astronauts.

He says the work he has produced that he is most proud of and believes has had the most impact is the paper he wrote discussing if sweat rates are inhibited when people are individuals. Subjects included both hyper and hypodehydrated individuals, and while he says it was not earth shattering, people are still quoting it today.