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A long-term stay of humans in space causes health problems and changes in protists and plants. Deep space exploration will increase the time humans or rodents will spend in microgravity (µg). Moreover, they are exposed to cosmic radiation, hypodynamia, and isolation. OMICS investigations will increase our knowledge of the underlying mechanisms of µg-induced alterations in vivo and in vitro. We summarize the findings over the recent 3 years on µg-induced changes in the proteome of protists, plants, rodent, and human cells. Considering the thematic orientation of microgravity-related publications in that time frame, we focus on medicine-associated findings, such as the µg-induced antibiotic resistance of bacteria, the myocardial consequences of µg-induced calpain activation, and the role of MMP13 in osteoarthritis. All these point to the fact that µg is an extreme stressor that could not be evolutionarily addressed on Earth. In conclusion, when interpreting µg-experiments, the direct, mostly unspecific stress response, must be distinguished from specific µg-effects. For this reason, recent studies often do not consider single protein findings but place them in the context of protein–protein interactions. This enables an estimation of functional relationships, especially if these are supported by epigenetic and transcriptional data (multi-omics). [ABSTRACT FROM AUTHOR]

INTRODUCTION: The effects of long-duration (213.0 ± 30.5 d) stays aboard the orbital station Mir and short-term (--10 d) spaceflights aboard the International Space Station (ISS) on the joint torques of various muscles and work capacity of knee extensors were studied in male cosmonauts. METHODS: Joint torque and muscle endurance testing was performed 30 d before and 3-5 d after a spaceflight, using a LIDO® Multi-Joint Isokinetic Rehabilltation System (USA). RESULTS: Greater postflight changes in maximal joint torque were observed for back, knee, and ankle extensors compared with flexors, and the difference was especially clearly seen after long-term spaceffights. The decrease in maximal joint torque of hip extensors substantially varied, being the greatest in voluntary concentric movements in a low-velocity high-force mode at angular velocities of 30 and 60°'s 1 (by 16 and 13%, respectively) and the lowest in high-velocity modes at velocities of 120 and 180° -s_1 (by 9 and 11 %, respectively). Muscle work capacity was inferred from the gradient of declining muscle force produced in a series of rhythmic voluntary concentric movements and was found to decrease after both short-and long-term spaceflights. The area under the muscle contraction curve decreased to a greater extent and in all regions of the curve after long-term spaceflights. The fatigue index averaged 0.90 ± 0.03 at baseline and remained much the same, 0.90 ± 0.04, after a short-term spaceflight. However, after a long-duration spaceflight, the fatigue index increased 14.1%o. DISCUSSION: The finding that the contractile functions and work capacity of muscles decrease more after long-term than after short-term spaceflights in spite of the physical training program of a certain type gave grounds to assume that physical training employed in long-term spaceflights were insufficient to simulate the daily mechanical load that the cosmonauts had before a spaceflight. [ABSTRACT FROM AUTHOR]