The Biopsy experiment allows researchers to take biopsies of their calf muscles before and after their stay on board the Space Station. This will allow scientists to begin developing an in-space countermeasure exercise program aimed at keeping muscles at their peak performance during long missions in space.Principal Investigator(s)
Johnson Space Center, Human Research Program, Houston, TX, United States
National Aeronautics and Space Administration (NASA)Sponsoring Organization
Human Exploration and Operations Mission Directorate (HEOMD)Research Benefits
Information PendingISS Expedition Duration:
June 2002 - October 2005Expeditions Assigned
5,6,7,9,10,11Previous ISS Missions
The Extended Duration Orbiter Medical Project measured astronauts' health after shuttle flights scheduled between 1989 and 1995. This provided some short-term data regarding muscles and muscle cells. STS-78 in 1996 was dedicated to muscle research and provided the cellular data for the determination of the effect of short duration flights on muscle. The Russian Mir program studied muscles after long term flight, but these did not provide enough information.
It is well established that space flight can result in loss of skeletal muscle mass and strength. This atrophy continues throughout a crew's mission, even if crewmembers adhere to a strict exercise regime. What researchers do not understand, however, are the effects that prolonged stays in microgravity have on skeletal muscles. Biopsy will evaluate changes in calf muscle function over long-duration space flights (30 to 180 days).
For the Biopsy investigation, a specially designed torque velocity dynamometer is used to measure muscle strength before and after flight. Biopsies are also taken from the soleus and gastrocnemius muscles of participants. This allows determination of the cell size and the structural properties of individual fast and slow muscle fibers. Chemical analysis of the biopsies determines muscle fiber structural changes involving myosin, a protein "molecular motor" that drives muscle contractions and cell divisions, enzymes, and substrates. Electron microscopy determines the relationship between thick and thin filament, the amount of myofilament loss, and changes in membrane-associated protein complexes found in skeletal muscle fibers and connective tissue that help the muscle resist stretch-induced damage.
It is well established that muscle mass and strength decrease during space flight. The atrophy of muscles in space can affect not only the performance of astronauts during missions, but it can lead to severe muscle injuries upon return to Earth. Astronauts landing on Mars may be susceptible to muscle injury once they step onto the planet. The exact cellular and biochemical events that produce these losses of mass and strength are not as well understood. Biopsy is the first experiment to tackle the cellular question in long-term space flight. The data from this experiment will be used to illustrate the structural and metabolic changes that occur within individual muscle fiber cells. This experiment will also help create a model that illustrates to what degree muscles deteriorate in space over time, which can be used to predict risks for long term flight. As the mechanisms of muscle deterioration due to space flight become clearer, scientists can pursue new methods to protect muscles for exploration-length missions.Earth Applications
As people age on Earth, muscle tissue tends to loose elasticity. The results of this investigation will provide a better understanding of muscle atrophy in the elderly population on Earth.
The crew's inflight log provides information about their daily exercise and diet, factors that play a role in muscle health. Limited mobility is required on landing day to minimize the stress placed on the calf muscles before the biopsy is performed.Operational Protocols
The crew undergoes performance tests on their right calf muscles using the TVD 90, 60, 30, and 15 days before launch. Magnetic Resonance Imaging (MRI) is conducted on L-90 and 30 before the TVD testing. A needle biopsy is taken from the right gastrocnemius and soleus muscles on L-45. Another biopsy is taken on the day the crew returns. Additional TVD performance tests are conducted on the right calf on R+7, 14, 21, and 30, and an MRI is taken of the calf at R+1 and 21.
The aim of this study was to examine muscle physiology and performance of the calf muscles (soleus and gastrocenemius) on astronauts who performed exercise routines during their 6-month stay on ISS. In particular, calf muscle volume, calf muscle performance, and muscle fiber physiology and microanatomy were assessed before and after space flight for these crewmembers who had access to the ISS treadmill, Treadmill with Vibration Isolation System, (TVIS), cycle ergometer, Cycle Ergometer with Vibration Isolation System, (CEVIS) and interim resistive exercise device (IRED). The exercise routine varied among the crewmembers with aerobic exercise performed ~5 hrs/wk at moderate intensity, and resistance exercise performed 3-6 days/wk incorporating multiple lower leg exercises. Despite the exercise programs, overall calf muscle volume significantly decreased by 13¬+2%, peak power decreased significantly by 32%, force-velocity characteristics were reduced significantly to -20 to -29% across the velocity spectrum, and there was a 12-17% shift in myosin heavy chain phenotype with a significant decrease in myosin heavy chain I fiber type along with a redistribution among the faster phenotypes. These data show a reduction in calf muscle mass and performance along with a slow-to-fast fiber type transition in the calf muscles, which are all qualities associated with muscle unloading. Peak force decreased in the Type I soleus muscle, which correlated with a significant decrease in muscle fiber diameter, and inversely correlated with the amount of treadmill running on ISS. This decline in peak force was also associated with an increase in thin filament density of the muscle fiber, which likely contributed to the 21 and 18% decline in maximal velocity in the soleus and gastrocnemius type I fibers, respectively. Taken together, the decrease in muscle performance, (peak power, peak force, peak force-velocity, and maximal velocity), combined with the muscle physiological and anatomical changes, (transition of the slow fiber types into the fast fiber types, increased thin filament density, and decreased fiber diameter and overall muscle volume), indicate that the exercise countermeasures provided on orbit during this study (June 2002 - October 2005) were not sufficient to provide the intensity needed to adequately maintain calf muscle performance and structure. Such a decrease in performance could affect crewmembers’ ability to perform specific tasks, including emergency egress and locomotor tasks upon return to a terrestrial environment, and also render them more susceptible to muscle injury. Since the completion of this study, there has been the addition of a second treadmill, the Combined Operational Load-Bearing External Resistance Treadmill, (COLBERT) to ISS as well as an improved resistance exercise device, the Advanced Resistive Exercise Device (ARED). The authors suggest that a new study be implemented to investigate the efficacy of these new exercise devices on ISS, as they provide high resistance and contractions over a wide range of motion that mimic the range occurring in Earth’s environment (Trappe 2009 and Fitts 2010).
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