Exercise in space mitigates low gravity

WATERLOO, Ontario, March 27 (UPI) -- Lengthy spaceflight affects cardiovascular responses, but not as dramatically as predicted indicating exercise mitigates the impact, Canadian researchers said.

Astronauts have been taking part in short spaceflight missions since 1961, but only recently began spending significantly longer times in space. Earlier studies showed astronauts on these extended missions suffered serious deficits from lengthy times in low-gravity, including dizziness when standing up, loss of bone mass and impaired muscle function.

In the current study, a research team has tested various cardiovascular measures in six astronauts on long-term missions aboard the International Space Station.

The researchers collected data from six male astronauts, ages 41-55, who were headed to the ISS on missions ranging from 52 to 199 days. Health data was collected before they left, a few weeks after they arrived and after they returned to Earth.

The study published in the Journal of Applied Physiology found heart rate, blood pressure and arterial baroreflex response were unchanged from pre-flight to in-flight. Left ventricular ejection times and cardiac output both increased in-flight while time between heartbeats, arterial pulse pressure and the blood pumped from the heart decreased.

On these particular missions, the six astronauts were each allotted 2.5 hours per day to set up for exercise, complete a workout, and clean up after the session, with options to exercise on a cycle, treadmill or resistance training, the study said.

"These exercise sessions appear to keep astronauts relatively healthy and prepared for return to Earth, despite the potentially negative effects of a low-gravity environment," the researchers said.