The effect of weightlessness on the spine
New observations of astronauts before and after four to seven month long missions to ISS has found the back pain many astronauts experience appears to be caused by significant muscle atrophy.
The MRI scans indicated significant atrophy of the paraspinal lean muscle mass —which plays a critical role in spinal support and movement—during the astronauts’ time in space. The lean muscle, or “functional,” cross-sectional area of the lumbar paraspinal muscles decreased by an average of 19 percent from preflight to immediate postflight scans. A month or two later, only about two-thirds of the reduction had recovered. There was an even more dramatic reduction in the functional cross-sectional area of the paraspinal muscles relative to total paraspinal cross-sectional area. The ratio of lean muscle decreased from 86 percent preflight to 72 percent immediately postflight. At follow-up, the ratio recovered to 81 percent, but was still less than the preflight value.
In contrast, there was no consistent change in the height of the spinal intervertebral discs. Dr. Chang and coauthors write, “These measurements run counter to previous hypotheses about the effects of microgravity on disc swelling.” Further studies will be needed to clarify the effects on disc height, and whether they contribute to the increase in body height during space missions, and to the increased risk of herniated disc disease.
These results are very encouraging, because they indicate that the back problems seen are mostly attributable to weakened muscles, not actual spinal damage, and can therefore be more easily mitigated by new exercises while in orbit.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
New observations of astronauts before and after four to seven month long missions to ISS has found the back pain many astronauts experience appears to be caused by significant muscle atrophy.
The MRI scans indicated significant atrophy of the paraspinal lean muscle mass —which plays a critical role in spinal support and movement—during the astronauts’ time in space. The lean muscle, or “functional,” cross-sectional area of the lumbar paraspinal muscles decreased by an average of 19 percent from preflight to immediate postflight scans. A month or two later, only about two-thirds of the reduction had recovered. There was an even more dramatic reduction in the functional cross-sectional area of the paraspinal muscles relative to total paraspinal cross-sectional area. The ratio of lean muscle decreased from 86 percent preflight to 72 percent immediately postflight. At follow-up, the ratio recovered to 81 percent, but was still less than the preflight value.
In contrast, there was no consistent change in the height of the spinal intervertebral discs. Dr. Chang and coauthors write, “These measurements run counter to previous hypotheses about the effects of microgravity on disc swelling.” Further studies will be needed to clarify the effects on disc height, and whether they contribute to the increase in body height during space missions, and to the increased risk of herniated disc disease.
These results are very encouraging, because they indicate that the back problems seen are mostly attributable to weakened muscles, not actual spinal damage, and can therefore be more easily mitigated by new exercises while in orbit.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
I had to deal with atrophy of my Infra & Supraspinatus muscles on my left shoulder blade because of pinched nerves in my neck. MAN O’ MAN talk about painful! There is also peculiar feeling of the muscle actually rotting away that goes along with it…
It got to the point to where I had near zero strength in those muscles before I got decompression surgery to relive the pressure on the nerves. I have most of the strength back, but they said the best I could hope for is about 80% return. Strength and mass.
I could see Astronauts ending up where they never returned to their full strength as well. No matter how much they exercised in space.
There’s a sure fire way to fix this problem without having to resort to time-consuming exercise regimes and vitamin cocktails. Get there faster.
All of this research into how the body reacts to weightlessness is just a stop gap measure because we refuse to invest in the technologies that would render it obsolete. If we had properly embraced NTR technology in the 60’s and 70’s, we wouldn’t be talking about multi year trips in weightlessness to get to Mars and back, it would be weeks to months.
And right along with Get there faster is Get there better. When will there ever be a serious effort into building a spacecraft that rotates? Short of aliens dropping by and giving us artificial gravity and FTL technologies, this is going to be the only way to get around for a while so what really is the holdup? I’ll answer that myself. The combination of a rotating spacecraft and NTR propulsion would make space travel both faster and less demanding on the human body, but there would be room for pork like the ISS. Yes it is supposed to be a prototype interplanetary spacecraft, but that’s not what it is. What it is is a political tool through which money is funneled and politicians can pat each other on the back and say “Look how cooperative we all are with our international partners.” Meanwhile humanity is still stuck on Earth.
Apologies if this wandered into ranting territory. I’m just annoyed how biology and pork always gets the front seats when existing and existing technology would solve the problems they are still failing to address.
A rotating space station would need to allow for walking and not the rotating bed theory that some have proposed. Bed rest in artificial gravity wouldn’t solve this spinal muscle atrophy problem.
Getting there faster could help but you also need to slow down.
wodun wrote: “Getting there faster could help but you also need to slow down.”
If the destination planet (or moon) has an atmosphere, aerobraking could reduce the amount of fuel needed to get into orbit. However, this also requires a more streamlined spacecraft; be careful of those solar arrays and antennas. A heavy manned craft may not slow very much in the curvature of Mars’s thin atmosphere.
Gene manipulation may provide an answer, at least in part.
A centrifuge must be used standing up vertically, I cannot imagine anything else. Sleeping horizontally in a centrifuge might maybe help the body normalize internal fluid pressures, but I don’t see how that could help the spine muscles from deteriorating. So an efficient neutralization of this problem requires a very large spaceship, larger than what Elon Musk suggest, spinning while people walk and work in them.
Luckily, Mars is close enough that human trips there don’t need any yet unproven microgravity mitigation measures. Gravity is actually the back worst enemy! How many thousands of backs doesn’t gravity break every day? In the future spending time in microgravity might be prescribed to back injured patients.
Microgravity isn’t more dangerous than 1g. It is just different.
BSJ said:
“I could see Astronauts ending up where they never returned to their full strength as well. No matter how much they exercised in space.”
This may soon be a past problem. Atrophy of the muscles is caused mostly by the evolutionary trick of the body reducing muscle mass when it is not needed, to compensate for famine, by dropping the amount of calorie consuming muscle cells. Famine was a common enough occurrence for most populations before the industrial revolution began.
What triggers muscle atrophy is the myostatin pathway. There is belief that an anti-myostatin vaccine will be allowed into human testing within 12 months. If it works as well in humans as in test animals, then it may become a norm for spaceflight that you get your myostatin shot before leaving.
Note that this will only affect muscle mass, and *not* bone mass. Indeed, even though exercise helps calcium phosphate deposition in the large bones, there are the ossicles of the middle ear. Whether they are threatened by freefall is still being worked out.