During the bed-rest study, possible countermeasures are tested against the negative effects of microgravity during space missions using various training methods. In this training group, proprioceptive training is combined with strength and endurance training.
In this blog about the DLR-NASA 'Sensorimotor Countermeasures Study (SMC)' bed-rest study, we report on the lives of participants and the work of the large team around them, and what it means to be part of such a major study.
60 days lying down for science – this is the everyday life of our participants currently taking part in the Sensorimotor Countermeasures bed-rest study. With the six-degree head-down position, we can simulate the effects of microgravity on the human body and also investigate measures to counteract its negative impacts. All daily activities such as eating, showering, leisure activities, as well as all examinations and tests are conducted while lying down.
Training room of the SMC bed-rest study
In :envihab, the hyperbaric chamber serves as a training room during the bed-rest study. Here, the daily training measures are carried out by the participants while they are lying down.
Future human space missions are expected to land on the Moon or Mars and thus, in some cases, extend far beyond the distances and periods of time covered to date – this is the backdrop to the study. This means that astronauts would be on their journeys much longer than those on regular missions to the International Space Station (ISS). In contrast to these 'short trips' into space, they would not be met by a team after landing that can take care of them and initiate appropriate measures in case any health problems arise.
Previous research shows that longer stays in microgravity disrupt coordination and balance. Together with the loss of muscle mass and bone density during spaceflight, this increases the risk of fall-related injuries when exploring the surface of the Moon or Mars. To prevent or atleast mitigate these effects on the body, we are conducting research at DLR into possible countermeasures using different training methods. A particular focus of the study is on balance, sensation and movement sequences.
In microgravity, the body can no longer rely on its 'normal' learned mechanisms of body perception and control through the vestibular system under Earth's gravity. In simple terms: up is no longer up. Control of the body and its sensitivity can be negatively affected by the degradation processes and the changes in balance. In our study, many experiments take place during the 60 days of bed rest, but some of them can only be carried out in an upright position for a before-and-after comparison.
Participants complete the circuit before and after their bed rest
On the first day of getting up, the subjects go through this circuit several times in succession, and both their time and the objects touched are recorded. This data is then compared with the runs before bed rest.
Since this study is primarily concerned with the vestibular system and coordination abilities, the most important day of the study is the one on which the participants stand up again. What influence did bed rest have on balance, and how effective were the selected countermeasures in protecting body balance and gait? In the SMC study, an obstacle course provided information on how the participants' balance and coordination abilities changed over the course of the study. Our participants complete the course before the start of bed rest and after 60 days, on the day they get up.
The countermeasures used in the study are designed for future long duration space missions and on the Moon or Mars. Due to limited resources, it is particularly important to take only what is needed on a mission. Therefore, various forms of countermeasures are being tested – from those requiring very light and simple devices to more complex and heavy training systems. The specifications for the training sessions performed by our participants were developed by NASA and finalised and implemented by our DLR team in Cologne. Training began as soon as bed rest started.
Muscle training while lying down
Training with electromyostimulation (EMS) would also be easy to perform in space because it does not require any large equipment and those training have to do little themselves
Four groups regularly perform the various sports programmes: three of our participants complete a 30-minute training session every day using electromyostimulation (EMS), in which the muscles are controlled from the outside with electrical impulses. This muscle training could also be easily performed in space because it does not require any large equipment and those training have little to do themselves. Muscles are stimulated electrically and the legs move without any input from the user, solely through the electrical stimulus. However, the soreness that results is the same as in conventional training. In our participants, four muscles were stimulated on each leg. For this, stimuli were applied to the thighs and lower legs. To ensure that the stimulation could always be applied at the same place, the corresponding points were marked with a pen on our participants skin.
Proprioceptive training in the SMC bed-rest study
In proprioceptive training, the participants 'stand' on a balance board and perform certain tasks, such as following different patterns with their feet
The second group undergoes what is known as proprioceptive training, which primarily trains body awareness and balance. To simulate training in microgravity as closely as possible on Earth, the participants lie with their upper body on a sort of stretcher with air nozzles mounted underneath, similar to an air hockey table. In addition, they are pressed onto a balance board attached to the wall using a pulley system towards their feet. The frictionless support of the upper body helps to balance the movements of the legs. The participants perform certain tasks, such as tracing various patterns displayed on a screen with their feet. The contact force can be increased and the exercises are performed, both single- and double-legged, three times a week for approximately 35 minutes.
Strength training, endurance training and proprioceptive training while lying down
During strength training, the entire leg musculature is trained, for example through squats and calf raises. Training sessions are also held six times a week on a recumbent bicycle ergometer.
In the third training group, the proprioceptive training is combined with strength and endurance training. This measure expands the strength and endurance training that has been conducted on the ISS to include balance board training, to determine whether this combination also improves coordination. The disadvantage of this countermeasure is that the equipment requires a lot of space, which will be in short supply on a future long-term mission. During strength training, for example, the entire leg musculature is trained through squats and calf raises. Training sessions on a bicycle ergometer also take place regularly, with exercises being performed three times a week for about 30 minutes. The load during cycling, in the form of weights or resistance, is always individually adapted to the performance capacity of the respective participant.
The fourth group is the control group, which does not do any training. This group is very important for the scientific study, because the data from the control group is used as a basis for comparing the success of the various training activities.
All subjects are very committed to their respective groups. Among some of the participants in the proprioceptive training, a small competition has started to see who can achieve the best score in coordination training. The group using electromyostimulation find their daily get-together in beds next to each other a nice, regular opportunity for conversation. They also like to invite other participants to their meetings, so an exchange is always guaranteed.
Now there are only a few days left until the participants have to get up after 60 days in bed. We are very excited to see the effects of the individual countermeasures and wish our participants the best of luck standing up!
