lowering blood pressure in spaceLowering blood pressure – space travel helps

Lowering blood pressure is important enough to make some of us go the extra mile to make healthy lifestyle changes – not many are prepared to go all the way to outer space though. Apparently NASA researchers studying astronauts who have stayed in space have found that three to six months up there can drop your blood pressure by up to 10 points.

Reporting at a press conference at the recent 2011 Annual Scientific meeting of the American Society of Hypertension, Dr Peter Norsk of NASA (Space Centre, Houston) described findings made by himself and research colleagues. There were some unexpected physiological changes too. For example, levels of some pressure raising hormones called catecholamines (for example epinephrine/adrenaline) were high, as was cardiac output. However total peripheral resistance decreased, as would be expected.

Looked at from a simple mechanical point of view one might expect a drop in blood pressure, as the heart is having to do less work to pump blood around the body against the effects of gravity. However, the scientists were surprised about the lower pressures given the increase in blood levels of catecholamines which normally would have the effect of raising blood pressure. They are postulating the effects of some other blood pressure lowering mechanism that counters this.

Whatever the findings, it is hoped that studying the astronauts will provide more insights into the way that blood pressure is controlled and hopefully lead to new and effective blood pressure lowering methods.

The blood pressure lowering effects of space were found not to be permanent, however. The scientists noted a rebound effect, one to two months after returning to earth, as the astronauts’ blood pressures returned to their pre-existing levels. In fact if anything, they were even slightly higher by one or two points.

Weight loss is advocated as being effective in lowering blood pressure, however these results show that weightlessness can do the trick too – that’s if you are prepared to stay up there. I guess given the costs, dangers, isolation and other disadvantages of space travel we won’t be seeing space health spas anytime soon!


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