I am going to talk about the results of this work because they come to confirm and reinforce many concepts that we deal with in this web.
This study used magnetic resonance imaging to measure muscle mass of the lumbar paravertebral musculature. They measured the musculature before the flight to the international space station where they spent six months. Upon returning to earth, the tests were repeated approximately every month and two months. The lumbar paravertebral musculature is the musculature that is in the back of the lower back and is the main responsible for stabilizing the vertebrae.
The results of the work show how astronauts, after spending time in space, lose strength in the lumbar extensor muscles. This alone may seem logical but it is very important, as we will see later. The lack of gravity does not require muscle contraction to maintain the posture or not to fall. It is well known that astronauts measure 5 cm more when returning from a space trip. This happens because the discs are not compressed by the weight of the body and when hydrated more they become larger. The sum of all the enlarged disks makes us measure more. In an earlier post he explained that humans measured about 2 cm more in the morning than at night. The explanation is similar although in space the disks are more discharged than in the bed. There are other factors that seem to influence, such as loss of natural back curves by lack of gravity. This causes the back to be “straighter” and to measure more.
And what is the loss of strength of the extensor muscles of the back? Half of the astronauts suffer from back problems when returning from space, flashy right? In addition, astronauts suffer more disc hernias after space flight than the normal population. The chances of having a hernia for these astronauts are increased more than four times, being the highest risk during the first year after being in space. The highest number of hernias occurs the first month after landing, which coincides with the period in which there is more atrophy of the musculature (by atrophy we refer to a loss of muscle capacities). This increase of hernias in the past gave rise to all kinds of theories about the harmful effects that could have to be in space. Today we know the explanation, which is much simpler. We know that the paravertebral musculature is fundamental for the stability of the lumbar vertebrae in the different postures and movements that we perform. We also know that when these muscles are atrophied we suffer the so-called chronic low back pain.
All this what can contribute? Astronauts have a clear motive for atrophy in the muscles of their back. In humans who live on earth this atrophy can come from two sites, basically. On the one hand, the sedentary lifestyle and lack of exercise favors muscle atrophy and can cause back problems. On the other hand, if we hurt ourselves by an accident or by taking weight in a bad posture, atrophy secondary to the damage of the back occurs. The pain and damage in the lumbar joints triggers a mechanism that causes atrophy of the musculature. As we commented in the post on chronic low back pain , we entered a vicious circle where the pain produces atrophy and the atrophy facilitates to have pain again.
Surgery is one of the factors that most atrophy the paravertebral musculature. When we leave surgery, the muscles have lost much of their strength and endurance capabilities. That is why it is so important to take great care of the efforts the first 2-3 months after having a herniated disc, for example. Such seemingly insignificant gestures as standing 20 minutes or stooping to put on a shoe can cause us to fall. As we have seen with the astronauts, the lack of strength makes us more prone to suffer low back pain and herniated discs. Understanding the concept we have treated in this post is basic to controlling our back problem.