Astronaut muscles waste in space

Astronaut muscles waste away on long space flights reducing their capacity for physical work by more than 40%, according to research published online in the Journal of Physiology.

This is the equivalent of a 30- to 50-year-old crew member's muscles deteriorating to that of an 80-year-old. The destructive effects of extended to skeletal muscle - despite in-flight exercise - pose a significant safety risk for future manned missions to Mars and elsewhere in the Universe.

An American study, led by Robert Fitts of Marquette University (Milwaukee, Wisconsin), was recently published online by The and will be in the September printed issue. It comes at a time of renewed interest in Mars and increased evidence of early life on the planet. NASA currently estimates it would take a crew 10 months to reach Mars, with a 1 year stay, or a total mission of approximately 3 years.

Fitts, Chair and Professor of Biological Sciences at Marquette, believes if astronauts were to travel to Mars today their ability to perform work would be compromised and, with the most affected muscles such as the calf, the decline could approach 50%. Crew members would fatigue more rapidly and have difficulty performing even routine work in a space suit. Even more dangerous would be their return to Earth, where they'd be physically incapable of evacuating quickly in case of an emergency landing.

The study - the first cellular analysis of the effects of long duration on human muscle - took calf biopsies of nine astronauts and cosmonauts before and immediately following 180 days on the International Space Station (ISS). The findings show substantial loss of fibre mass, force and power in this muscle group. Unfortunately starting the journey in better physical condition did not help. Ironically, one of the study's findings was that crew members who began with the biggest muscles also showed the greatest decline.

The results highlight the need to design and test more effective exercise countermeasures on the ISS before embarking on distant space journeys. New exercise programmes will need to employ high resistance and a wide variety of motion to mimic the range occurring in Earth's atmosphere.

Fitts doesn't feel scientists should give up on extended space travel. 'Manned missions to Mars represent the next frontier, as the Western Hemisphere of our planet was 800 years ago,' says Fitts. 'Without exploration we will stagnate and fail to advance our understanding of the Universe.'

In the shorter term, Fitts believes efforts should be on fully utilizing the so that better methods to protect and bone can be developed. 'NASA and ESA need to develop a vehicle to replace the shuttle so that at least six crew members can stay on the ISS for 6-9 months,' recommends Fitts. 'Ideally, the vehicle should be able to dock at the ISS for the duration of the mission so that, in an emergency, all crew could evacuate the station.'

Explore further

NASA Scientist to Discuss Preparations for Manned Flights to MARS

More information: “Prolonged Space Flight-Induced Alterations in the Structure and Function of Human Skeletal Muscle Fibres” by Robert H. Fitts, Scott W. Trappe, David L. Costill, Phillip M. Gallagher, Andrew C. Creer, Patricia A. Colloton, James R. Peters, Janell G. Romatowski, James L. Bain, and Danny A. Riley. To be published 15 September 2010, The Journal of Physiology, volume 588 issue 18
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Citation: Astronaut muscles waste in space (2010, August 17) retrieved 17 October 2019 from
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Aug 17, 2010
It would be interesting to convert the energy released by astronauts during the exercise into electricity which can be used in the spacecraft.

Aug 17, 2010
The muscle could loss strength in space for about week and two or four day. The mass a of the bone could break or fragment a bone.

Aug 17, 2010
Agreed, Question - there's a reason all of the SciFi writers went with variations of wheel space stations when they wrote their stories. The question is why the ISS isn't. The Shuttle could certainly have brought up segments that could be connected in more than just a linear fashion. One hub, four extension booms, and four labs would have made for a nicely rotate-able station - In fact, take the hub, two booms, and two labs in one or two trips, then the rest in follow-on trips. Then attach a second hub to the first, and go out further, making a 6-way flower. Find out just how much spin-G you need to help against this muscular degeneration.

Aug 17, 2010
The muscle could loss strength in space for about week and two or four day. The mass of the bone could break or fragment a bone.

Aug 18, 2010
There are probably a lot of reasons why a centrifugal design wouldn't work for the ISS, off the top of my head one of them is low-g experiments. Why not fit the astronauts with rubber band suits that apply tension to various muscle groups?

Aug 18, 2010
Seeing the difficulty the ISS faced when replacing a simple ammonia pump, it's hardly surprising that they haven't installed a giant rotating wheel

Aug 18, 2010
Why no mention of creating artificial gravity by way of centrifugal force? We could tether two identical spaceships together by an enclosed walkway and have them rotate around each other.
We ought to be experimenting with this in earth orbit now.

That's what I keep wondering too. Any acceleration of 9.8m/s is identical to gravity, no matter how its produced. I like your and jamey's ideas on how to do this. As for low-g experiments, you could still have those in the hub section where there is no artificial gravity. The astronauts would spend most of their time in gravity on the outer edge, which would help mitigate any loss.

Aug 18, 2010
Centrifugal force would not work because connecting to objects with a 'bridge' is that this would create huge amounts of shear stress at the end points.

hold a sheet of paper in your hand as if you are going to tear it in half. you probably have your thumbs on opposite sides of your intended tear point, and you probably are trying to tear it by bringing one hand closer and moving the other farther away. -- that pressure you are exerting on the paper is shear stress exactly like shears or scissors exert on paper.

You may say that shuttles are hoked up to the ISS all the time - yes but with a very short semi flexible tube.

There is tensile stress to deal with - which may be bigger -- if two connected objects are rotating and the object is to produce centrifugal forces then they are pulling away from each other -- this force could be huge - imagine pulling taffy apart.

There is one more force to deal with if the two ships have even the slightest rotation ...

Aug 18, 2010
The biggest issue I can see with a rotating platform is with transferring the power from stationary solar panel arrays to the main station. Even a non-contact tranformer-like transfer of energy would induce magnetic repel forces (mechanical losses) that would tend to effect the rotation of both systems. This would require a small amount of repeated thrust to counter.

Have any studies been published that indicate the minimum ID of a single cylinder that could rotate to provide 1G of centrifugal force, and would not cause vertigo? I don't know of any.

Aug 18, 2010
What is the time to mortality if someone stays in space/micrograv? 180 days can turn a 30 year old into an 80 year old, with a 40% reduction in physical capacity. Going to mars and back would be 50%, so what would that be here? More like 90-95 years of age? Most people die well before that age, so it's kind of a suicide mission with current technology.

Even if you make it back can you imagine the physical therapy and rehab regimen? They may have to be slowly lowered from orbit and adjusted to gravity gradually as they return.

Aug 18, 2010
An interesting read about some of the issues with rotating platforms:


Aug 18, 2010
It's not just muscle loss, there is significant bone density loss from microgravity. I remember in the late 1980's NASA funded research into bear hibernation. Bears can actually preserve muscle mass and bone density, and in some cases increased the bone density during hibernation. About 1990 I sent an e-mail to the primary researcers per the info provided, but they didn't respond.

Aug 18, 2010
There has been some interesting research in drugs to prevent muscle loss, such as myostatin-inhibitors. Very little mention of this. Of course the problem as discussed is that its not just muscle but tendons and bones as well that need their own drug induced adjustment. Some interesting follow ups:

Aug 18, 2010
The problem with rotating spaceships is that the system turns into a vomit comet.

Because things inside the ship also have angular momentum of their own. If you jumped up facing opposite the direction of the rotation, you'd automatically do a backflip. It would feel like an invisible torque is constantly trying to twist you down.

The rate of rotation of such a ship would need to be extremely low - two, three hours per rotation so you would't be annoyed by the effect anymore. Thigs still would't fall down quite like they're supposed to, and you'd probably feel a slight wobble all the time.

Aug 18, 2010
NASA should reconsider the short journey options. It would reduce a lot of problems associated with lengthy spaceflight such as radiation exposure. It is not a given that the journey take 10 months - that is about ideal for a minimal free trajectory. If instead they dock with a larger booster in Earth orbit they can increase speed to make the journey much shorter, say 5 months, and use the same booster to brake at the other end. (problem: needs large re-useable reliable engine.) A similar procedure for the return craft. This is not economically 'efficient' but might be the best option given the serious difficulties described with long spaceflights. Seems to me they'll need to eventually anyway.

Aug 18, 2010
Gravity plating. Star Trek has it, we should too. Hopefully in the "near" future we'll figure out how to manipulate gravity with some kind of gravity pump or gravity emitters that emit gravitational fields. This would solve two problems, a gravity environment and a good propulsion device. Of course this is purely theoretical and this comment is not meant to imply that this will happen tommorrow.

Aug 22, 2010
Would an increase in atmospheric pressure possibly counter the muscle effects due to lack of gravity? Go to Mars at 2 bars?

Aug 22, 2010

The rate of rotation of such a ship would need to be extremely low - two, three hours per rotation so you would't be annoyed by the effect anymore. Thigs still would't fall down quite like they're supposed to, and you'd probably feel a slight wobble all the time.

Two, three hours per rotation needed? That sounds like extreme overkill.. according to wikipedia, 30 seconds per rotation should be enough:

"It is generally believed that at 2 rpm or less no adverse effects from the Coriolis forces will occur"


Aug 23, 2010
Ah, from your same link:

"To reduce Coriolis forces to livable levels, a rate of spin of 2 rpm or less would be needed. To produce 1g, the radius of rotation would have to be 224 m (735 ft) or greater, which would make for a very large spaceship."

I'd say large, but do-able. The entire structure could be wrapped with high tension cabling, much like an old-style wooden water tank.

Sep 02, 2010
Would an increase in atmospheric pressure possibly counter the muscle effects due to lack of gravity? Go to Mars at 2 bars?

No, mere atmopheric pressure (if we could survive that over the long term) would have no effect on muscle, bone and connective tissue loss. The body needs to work to stay health. Atmospheric pressure simply pushes against us from all directions and doesn't add to muscular effort. After years at such a pressure we would likely asphyxiate upon returning to normal earth pressures.

It appears that the internal working surface of the ring or cylinder should be about 450 meters in diameter to approximate 1g of force at 2 rpm. This should be well within the realm of present technical capabilities. Whether humanity has the will to do so is the real question.

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