Professor Researched Gravitational Force on NASA Project
The way the next generation of space suits are constructed may owe much to a piece of sewer pipe and a kayak spray skirt. While these are not items you would normally associate with a NASA project to measure shifts in body fluids due to gravitational forces, they were essential to research conducted for NASA by Jeanne Foley, assistant professor of exercise science in the Department of Kinesiology.
Photo Caption: Jeanne Foley, assistant professor of exercise science in the Department of Kinesiology takes the blood pressure of graduate student Karin Allor before a session in the MRI.
The study, funded by a Michigan Science Grant Consortium research seed grant, uses magnetic resource imaging (MRI) to measure the volume changes of fluid in the legs caused by high gravitational forces (G-forces), such as those involved in the lift-off of the space shuttle, and how those forces affect the flow of blood in the human body. The greater the fluid shift to the lower extremities of the body, the greater chance of the pilot or astronaut losing consciousness during lift-off.
The project involved a number of undergraduate and graduate volunteers led by Karin Allor, an exercise physiology doctoral candidate. Foley and Allor needed to solve the problem of building a pressure chamber small enough to fit around the waist and hips of average men and women and still fit in the tunnel of an MRI machine, which is only about 17 inches in diameter. The chamber also had to be constructed completely of nonmetallic materials, since even a tiny piece of metal can cause distortions in MR images.
The subject slides through the kayak spray skirt, which is attached to the sewer pipe and then the spray skirt is tightened to it can be pressurized by a vacuum pump. Then it is up on the table for a trip inside the imager.
"The pressure in the chamber is produced by a vacuum pump attached to a port in the tube by a long rubber hose," said Foley. "The pump, made of metal, cant be located near the strong magnetic field of the MRI machine.
"The pressure itself is measured by a gauge attached to the pump, and everybody starts out at the same pressure, measured by the same units used to measure blood pressure. We increase the pressure every six minutes until the subject begins to show signs of fainting. But we dont actually continue to the point of fainting."
Foley said the researchers are also monitoring blood pressure and heart rate, and a drop in blood pressure or a big increase in heart rate are signs to stop. There is also a researcher in the MRI chamber monitoring the subject for other signs such as pallor of the skin, rapid breathing, sweating and feelings of nausea.
"What we find is that the subjects go along just fine, and then suddenly they start to exhibit these signs and we release the pressure immediately, upon which the relief is virtually instant," said Foley.
An initial study indicated that fluid shifts in
females might be substantially more than with males. If such a gender difference was
found, the design of flight gear, development of an optimal physical training program for
pilots and astronauts, and evaluation of recruiting parameters would need to be
reconsidered, putting an additional strain on NASA's
"Our initial results showed a rather striking gender difference," said Foley. "Females had more fluid shift than males. And that doesnt seem to be holding up in the extension of the study under the NASA grant."
Another variable, how physical fitness affects fluid shifts, is the next area of focus for the research. Foley's research indicates that high levels of aerobic fitness may adversely effect fluid shifts in a human body under strong gravitational forces.
"In one of the few instances where being aerobically fit may be, in one sense, bad for you," said Foley. "More aerobically fit people, for example endurance runners, seem to have bigger fluid shifts and suffer potential fainting more so than less-fit people."
Although the grant ended in August, Foley and her research team are continuing work on the project. Images from the study will also be used in Foley's undergraduate applied anatomy classes.
Jeanne Foley is an assistant professor of kinesiology, with an adjunct appointment in the Department of Physiology. Foley earned a B.A. ('75) from St. Olaf's College, M.A. ('77) in mathematics from the University of Wyoming, and a M.S. (81) in exercise physiology and Ph.D. (90) in physiology from Michigan State University. She has been with the Department of Kinesiology since 1991.