"Without sildenafil, their performance went down more than others," Friedlander said. "With it, it brought them back up to the levels of the non-responders." The results suggest that the responders experienced a greater degree of constriction of the vessels in the lungs at altitude and therefore benefited more from the vessel relaxation effects of sildenafil.
"One of the messages of the paper is that not everybody benefits," Friedlander said. Sildenafil could be considered as a treatment for those who suffer most at altitude but, because of side effects that can include severe headaches and the apparent inability to help some people, it should not be taken as an exercise aid by everyone, she said.
The bigger picture
This study adds to the scientific knowledge of what physiological factors limit performance at altitude, including the role that cardiac output plays, Friedlander said. For instance, physiologists don't know why some people have trouble at altitude and may develop illnesses such as acute mountain sickness or high altitude pulmonary edema while others adapt quickly. Studies like this may help identify some of the underlying differences between people and lead to better treatments.
In future studies, Friedlander wants to identify:
Friedlander and her team are working on issues that could apply to those who have to rapidly acclimatize to high altitude. For instance, when soldiers deploy to Afghanistan, they must quickly undertake physically t
Source:American Physiological Society