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1.
Bone loss in the lower leg during 35 days of bed rest is predominantly from the cortical compartment
Joern Rittweger, Boštjan Šimunič, Giancarlo Bilancio, Natale Gaspare De Santo, Massimo Cirillo, Gianni Biolo, Rado Pišot, Ola Eiken, Igor B. Mekjavić, Marco Narici, 2009, original scientific article

Abstract: Immobilization-induced bone loss is usually greater in the epiphyses than in the diaphyses. The larger fraction of trabecular bone in the epiphyses than in the diaphyses offers an intuitive explanation to account for this phenomenon. However, recent evidence contradicts this notion and suggests that immobilization-induced bone loss from the distal tibia epiphysis is mainly from the cortical compartment. The aim of this study was to establish whether this pattern of bone loss was a general rule during immobilization. Wemonitored various skeletal sites with different tissue composition during 5 weeks of immobilization. Ten healthy male volunteers with mean age of 24.3 years (SD 2.6 years) underwent strict horizontal bed rest. Bone scans were obtained during baseline data collection, at the end of bed rest and after 14 days of recovery by peripheral Quantitative Computed Tomography (pQCT). Sectional images were obtained from the distal tibia epiphysis (at 4% of the tibia's length), from the diaphysis (at 38%), from the proximal metaphysis (at 93%) and from the proximal epiphysis (at 98%), as well as from the distal femur epiphysis (at 4% of the femur's length) and from the patella. Relative bone losses were largest at the patella, where they amounted to - 3.2% (SD 1.8%, p < 0.001) of the baseline values, and smallest at the tibia diaphysis, where they amounted to - 0.7% (SD 1.0%, p = 0.019). The relative losses were generally larger from cortical than from trabecular compartments (p = 0.004), and whilst all skeletal sites depicted such cortical losses, substantial trabecular losses were found only from the proximal tibia epiphysis. Results confirm that the differential losses from the various skeletal sites cannot be explained on the basis of trabecular vs. cortical tissue composition differences, but that endocortical circumference can account for the different amounts of bone loss in the tibia. The present study therefore supports the suggestion of the subendocortical layer as a transitional zone, which can readily be transformed into trabecular bone in response to immobilization. The latter will lead to cortical thinning, a factor that has been associated with the risk of fracture and with osteoarthritis.
Found in: ključnih besedah
Summary of found: ...space flight, simulated microgravity, osteoporosis, exercise, pQCT, ...
Keywords: space flight, simulated microgravity, osteoporosis, exercise, pQCT
Published: 15.10.2013; Views: 2171; Downloads: 56
URL Full text (0,00 KB)

2.
Functional impairment of skeletal muscle oxidative metabolism during knee-extension exercise after bed rest
Desy Salvadego, Stefano Lazzer, Mauro Marzorati, Simone Porcelli, Enrico Rejc, Boštjan Šimunič, Rado Pišot, Pietro Enrico Di Prampero, Bruno Grassi, 2011, original scientific article

Found in: ključnih besedah
Summary of found: ...microgravity, muscle atrophy, physical deconditioning, exercise tolerance, near-infared...
Keywords: microgravity, muscle atrophy, physical deconditioning, exercise tolerance, near-infared spectroscopy, skeletal muscle, bed rest
Published: 15.10.2013; Views: 2002; Downloads: 79
URL Full text (0,00 KB)

3.
Effect of 5 weeks horizontal bed rest on human muscle thickness and architecture of weight bearing and non-weight bearing muscles
Maarten D. de Boer, Olivier Seynnes, Pietro di Prampero, Rado Pišot, Igor B. Mekjavić, Gianni Biolo, Marco Narici, 2008, original scientific article

Abstract: The aim of the present study was to investigate the changes in thickness, fascicle length (L f) and pennation angle of the antigravity gastrocnemiusmedialis (GM) and vastus lateralis (VL) muscles, and the non-antigravity tibialis anterior (TA) and biceps brachii (BB) muscles measured by ultrasonography in ten healthy males (aged 22.3 +/- 2.2 years) in response to 5 weeks of horizontal bed rest (BR). After BR, muscle thickness decreased by 12.2 +/- 8.8% (P < 0.05) and 8.0 +/- 9.1% (P < 0.005) in the GM and VL, respectively. No changes were observed in the TA and BB muscles. L f and pennation angle decreased by 4.8 +/- 5.0% (P < 0.05) and 14.3 +/- 6.8% (P < 0.005) in the GM and by 5.9 +/- 5.3% (P < 0.05) and 13.5 +/- 16.2% (P < 0.005) in the VL, again without any changes in the TA and BB muscles. The finding that amongst the antigravity muscles of the lower limbs, the GM deteriorated to a greater extent than the VL is possibly related to the differences in relative load that this muscle normally experiences during daily loading. The dissimilar response in antigravity and non-antigravity muscles to unloading likely reflects differences in loading under normal conditions. The significant structural alterations of the GM and VL muscles highlight the rapid remodelling of muscle architecture occurring with disuse.
Found in: ključnih besedah
Summary of found: ...muscle, disuse, microgravity, atrophy, ...
Keywords: muscle, disuse, microgravity, atrophy
Published: 15.10.2013; Views: 2207; Downloads: 81
URL Full text (0,00 KB)
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4.
Computerized cognitive training mitigates detrimental effects of simulated microgravity environment
Uroš Marušič, Nina Mohorko, Rado Pišot, Mitja Gerževič, Matej Plevnik, Voyko Kavcic, 2015, published scientific conference contribution abstract

Found in: ključnih besedah
Summary of found: Zadetek v naslovu
Keywords: bed rest, cognitive training, simulated microgravity
Published: 15.10.2015; Views: 1727; Downloads: 23
URL Full text (0,00 KB)

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