On August 27th, Danish astronaut Andreas Mogensen made history. He is the first European astronaut to pilot the SpaceX Dragon spacecraft to the International Space Station (ISS). Over the next six months, Mogensen will conduct over 30 research activities, including 3D printing in space, virtual reality, and storm chasing to better understand atmospheric phenomena. One experiment that fascinates the scientific community is the ESA ‘s testing of a device against muscle loss.
A long-known medical consequence
Muscle loss in astronauts is one of the inevitable medical consequences of long-term space missions. Previous research has shown that an astronaut between the ages of 30 and 50 who spends six months in space loses half of their strength. This essentially means they return home with the muscles of an octogenarian.
New experiment aims to reduce these effects by electrically stimulating certain muscles to regain mass. Ultimately, it is expected that this stimulation will accelerate recovery. With the interest in long-duration space missions to the Moon and even Mars, this method could be useful in counteracting the effects of microgravity on human explorers and keeping them healthy, say scientists.
Method, called Neuromuscular Electrical Stimulation (NMES), is a well-known rehabilitative strategy on Earth for patients experiencing prolonged periods of physical inactivity (ref.). Short electrical impulses on target muscles cause relatively strong contractions, ultimately compensating for the effects of prolonged disuse. However, in space, the method has never been tested.
Setting up the study
Mogensen, from the ESA, is the first subject of this experiment against muscle loss. He will belong to what is called a control group, meaning he represents a normal astronaut who will not undergo actual electrical stimulation. He will perform measurements to assess his muscle health before and after his six-month flight. Data collected will serve as baseline statistics for future astronauts treated with NMES during space missions.
Second group of astronauts will perform the same measurements but after undergoing electrical stimulation. The results of both groups will then be compared to judge whether the treatment has improved muscle health.
Certainly, this new method integrates and does not replace the current exercise regimen followed by astronauts during space missions. On the ISS, the crew exercises for at least two hours every day, which is a crucial countermeasure against muscle weakening.
How astronauts train today
Physical exercises are specific to space agencies and are also tailored to the individual. For example, according to a 2019 study, astronauts from the United States, Japan, China, and Canada follow resistance and aerobic training. In contrast, Russian cosmonauts prefer to use treadmills and stationary bikes among the equipment.
The effectiveness of these countermeasures varies widely among astronauts. A study (ref.) that monitored two astronauts during six months of spaceflight showed that despite high-intensity training, the crew still experienced muscle loss. Therefore, the NMES method, which requires fewer resources than a mini-gym in space, could be an accessible and useful system that complements daily exercises.
Although there have been no reported long-term safety issues so far, this method has some limitations. It may not always activate the entire muscle, and the effects of electrical stimulation on certain organs that deteriorate in space, such as those associated with the skeletal and cardiovascular systems, are not yet well understood.