Cardio research probes puzzle of fainting astronauts

Richard Hughson with assistant trying to resuscitate a fainted astronautAstronauts living on the International Space Station (ISS) regularly do experiments for Earth-bound researchers in the station’s near-zero gravity. Sometimes they are the experiment.

Canadian astronaut Robert Thirsk spent a record six months on ISS in 2009. He was part of the CCISS (Cardiovascular and Cerebrovascular Control on Return from the International Space Station) research project begun in 2001, sponsored by CSA and NASA, and led by Richard Hughson, a kinesiology professor, University Research Chair, and head of the Cardiorespiratory and Vascular Dynamics Lab at Waterloo.

Hughson, a leading scientist whose publications are among those most cited in his field, has been researching the effects of weightlessness on the cardiovascular system for more than 20 years.

It’s known that the weightlessness of space causes travellers to become less fit, with bones, muscles, heart, and other systems not being challenged by gravity. But why are so many astronauts light-headed, some even fainting, on return to Earth?

Seeking answers, Hughson gathered data before and after the mission to measure the performance of heart and blood vessels. In space, the astronauts monitored their heart rate and blood pressure and logged time spent exercising.

Hughson found that the astronauts came home surprisingly fit, yet some still experienced lightheadedness. A clue could lie in the finding that after the mission, their hearts were working faster but pumping out smaller amounts of blood with each beat, like the hearts of sedentary people.

This research is not just for elite spacemen; ordinary Earthlings can benefit as well. Both astronauts and couch potatoes can experience the physical changes that resemble accelerated aging, Hughson says, and the same restorative techniques and approaches could apply to both. “The role that physical exercise plays in cardiovascular health and general fitness can’t be over-emphasized.”