Colonisation of Mars
Six BFRs will begin to build a city on Mars starting 2022SpaceX

Microgravity (not zero gravity, there's no such thing) is found to have serious negative effects on the human body, especially internal organs and muscles.

Scientists set about studying the impact of 21-day flights to such environments of microgravity, or places that exert less gravity than Earth, like Mars and the Moon. These are two spots in the Solar System that humans are actively trying to colonize as of now and in the lack of Earth level gravity can place stress on internal organs, bones, muscles, including cardiovascular, respiratory and nervous systems, notes a report by EurekaAlert.

Apart from exposing spacefarers to low gravity situations, traveling to Mars, for example, will also mean spending extended periods in low oxygen environments. The resulting hypoxic stress will intensify the low gravity symptoms, researchers believe. Mitochondria – the powerhouse of cells– produce energy using oxygen in a process called oxidative metabolism. Skeletal muscles are used for movement and to be active requires energy that cells make using oxygen. Therefore, researchers went into the study assuming that low oxygen environments could impair functions of the muscular system. The study, however, proved that muscles take more damage from inactivity than from the lack of enough oxygen. In fact, the findings also suggest that impairments caused by microgravity do not really get aggravated by hypoxic stress.

"This research will help prepare astronauts for spaceflight and it improves our understanding of how muscles respond to long periods of inactivity in association with hypoxia," said Bruno Grassi, the chief investigator of the project.

"Future studies will have to investigate in more detail the mechanisms responsible for the observed findings. The results obtained on skeletal muscles, moreover, will have to be interpreted in conjunction with those deriving from other studies of the PlanHab project (a multinational team of researchers), dealing with the cardiovascular, respiratory, immune and central nervous systems and metabolism," he added.

If all goes according to plan, it is likely that humans will indeed land on Mars by 2024, so it is important that the research is in and people are prepared to face the stresses of living on Mars.