Muscles and nervous system: Space research helps combat degeneration

Injuries do not just happen to athletes: along with surgeries, they are often the reason for prolonged bed rest. Meanwhile, extended physical inactivity can trigger changes in muscles and the nervous system. Sports medicine wants to counteract these negative effects and use insights from space research in the future. This was a topic that was featured at the MEDICA MEDICINE + SPORTS CONFERENCE at MEDICA 2022.

In this MEDICA-tradefair.com interview, Prof. Ramona Ritzmann explains how inactivity affects the neuromuscular system and she reveals insights sports medicine can learn from space research.

Prof. Ritzmann, your lecture at the MEDICA MEDICINE + SPORTS CONFERENCE was titled "Adaptation of the neuromuscular system to disuse – From space to clinic". What was the essence of your presentation?

Prof. Ramona Ritzmann: "Space" and "clinic" do not have an obvious connection as fields. However, the topic holds the promise to drive synergies between them: the human neuromuscular system weakens and deteriorates in space over time. The same applies to patients who are on bed rest in hospital after surgery, for example.

This pertains to bedridden patients, who must lie in bed for a long time?

Ritzmann: It does not necessarily have to be for a long time. There are controlled studies in space science in which healthy people are on prolonged bed rest. Being motionless is an extreme state for human beings because our human body was designed to move. The studies revealed the first adaptations to the neuromuscular system after just two days.

The processing of sensory information and the integration of motor function – that being control of muscles – change in the nervous system. We also know that muscles lose volume and physiological cross-sectional area over time. The contractile muscle mass decreases.

Applied to the clinical setting, this information is relevant as it pertains to patients who must stay in bed for a few days. It is even more pertinent for those who must spend extended time lying down, let’s say a month or two in the ICU, as these are progressive adaptations, meaning they gradually increase over time.

Where does sports medicine intersect with this?

Ritzmann: Athletes have a higher risk of joint injuries or surgeries. This often leads to a reduction in joint amplitude of movement. Athletes must not put any stress or just decreased load on the affected body part. These are precisely the types of conditions that cause degeneration. Especially in competitive sports, the loss of muscle tissue has very dramatic effects since athletes had to build muscle and strength over years and optimize the contractile structure.

The topic is also relevant in amateur sports as it affects the general public. When people hurt themselves after a fall – especially older adults – and are forced into prolonged immobility, or when they are bedridden for an extended time due to an infection – as some were due to the COVID-19 pandemic – they share the same experience. The considerable effect on the muscles and the central nervous system when the body does not get any physical activity, is not something we can simply ignore and brush aside.

Has your research already resulted in actionable insights that can benefit sports medicine?

Ritzmann: Our studies and the modeling of degeneration have enabled us to understand how quickly muscles atrophy, recognize when this degeneration process occurs the fastest and realize that the process no longer continues after a certain time. This happens after about a year when the process reaches the saturation point. We also learned how degeneration occurs in the central nervous system and at what levels of the brain and the spinal cord it manifests.

Nonetheless, the most important issue pertains to counteracting these settings. What counteractive measures can one take in situations in which the body moves less but in which you want to preserve and maintain systems as much as possible? What tools can be applied in sports medicine, sports science, and high-performance sport to combat all these degenerative effects? Space research explicitly studies these aspects.

Looking back, how do you rate your participation in the MEDICA MEDICINE + SPORTS CONFERENCE?

Ritzmann: I think it was important to address the topic in this forum and to explore it from a transdisciplinary perspective. Sports medicine and sports science give much thought to performance and training, but degeneration takes a bit of a backseat, even though most people will sustain an injury or need surgery at some point in their lives and then have this experience. Top-level athletes indicate these are often the most difficult phases they must overcome in their careers. But if they manage to overcome these tough times, they come out stronger. I consider this an important message, and I hope I was able to convey it via this venue.