The aim of this investigation was to document the exercise program used by crewmembers ( n = 9; 45 ± 2 yr) while aboard International Space Station (ISS) for 6 mo and examine its effectiveness preserving calf muscle characteristics. Before after spaceflight, we assessed volume (MRI), static dynamic performance, fiber types (gastrocnemius soleus). While on ISS, had access a running treadmill, cycle ergometer, resistance device. regimen varied among with aerobic performed ∼5 h/wk at moderate...

1 Soleus biopsies were obtained from four male astronauts 45 days before and within 2 h after a 17 day spaceflight. For all astronauts, single chemically skinned post-flight fibres expressing only type I myosin heavy chain (MHC) developed less average peak Ca2+ activated force (Po) during fixed-end contractions (0.78 ± 0.02 vs. 0.99 0.03 mN) shortened at greater mean velocity unloaded (Vo) (0.83 0.64 fibre lengths s−1) than pre-flight fibres. 3 The flight-induced decline in absolute Po was...

Soleus muscle atrophy was induced by hindlimb unloading of male Sprague-Dawley rats (305 +/- 15 g) for 4, 7, and 10-14 days. Controls (291 14 were housed in vivarium cages. electromyogram (EMG) activity recorded before during tail suspension. Unloading caused progressive reduction the muscle-to-body weight ratio. After days, type I IIa fibers decreased area 63 47%, respectively. Subsarcolemmal mitochondria myofibrils degraded more rapidly than intermyofibrillar cell membrane. 10 3% exhibited...

Histochemical and ultrastructural analyses were performed postflight on hind limb skeletal muscles of rats orbited for 12.5 days aboard the unmanned Cosmos 1887 biosatellite returned to Earth 2 before sacrifice. The antigravity adductor longus (AL), soleus, plantaris atrophied more than non-weight-bearing extensor digitorum longus, slow muscle fibers atrophic fast fibers. Muscle fiber segmental necrosis occurred selectively in AL soleus muscles; primarily, macrophages neutrophils infiltrated...

Spaceflight (flight) and tail suspension-hindlimb unloading (unloaded) produced significant decreases in fiber cross-sectional areas of the adductor longus (AL), a slow-twitch antigravity muscle. However, mean wet weight flight AL muscles was near normal, whereas that suspension unloaded significantly reduced. Interstitial edema within AL, but not appeared to account for this apparent disagreement. In both experimental conditions, oxidative fibers atrophied more than fast-twitch...

Abstract Prolonged exposure to hand‐transmitted vibration can cause debilitating neural and vascular dysfunction in humans. It is unclear whether the pathophysiology involves simultaneous or sequential injury of arteries nerves. The mechanism was investigated a rat tail model, containing nerves structurally similar those human hand. Tails were selectively vibrated for 1 9 days with remainder animal at rest. One bout 4 h/day, 60 H Z , 5 g (49 m/s 2 ) acceleration, injured endothelial cells....

The purpose of this study was to examine the effect prolonged bed rest (BR) on peak isometric force (P0) and unloaded shortening velocity (V0) single Ca(2+)-activated muscle fibers. Soleus biopsies were obtained from eight adult males before after 17 days 6 degrees head-down BR. Chemically permeabilized fiber segments mounted between a transducer position motor, activated with saturating levels Ca2+, subjected slack length steps. V0 determined by plotting time for redevelopment vs. step...

Soleus muscle fibers were examined electron microscopically from pre- and postflight biopsies of four astronauts orbited for 17 days during the Life Microgravity Sciences Spacelab Mission (June 1996). Myofilament density spacing normalized to a 2.4-μm sarcomere length. Thick filament (∼1,062 filaments/μm 2 ) (∼32.5 nm) unchanged by spaceflight. Preflight thin (2,976/μm decreased significantly ( P < 0.01) 2,215/μm in overlap A band region as result 17% loss 9% increase short filaments....

Abstract Previously, solei from rats orbited 12.5 days aboard Cosmos 1887 biosatellite were biopsied 48–56 hours postflight. These atrophic muscles showed severe pathology. Designing a ground‐based model of that space flight, we tested the hypothesis 48 postflight muscle reloading induced pathological changes. Rats subjected to hindlimb suspension unloading and immediately after or returning normal weightbearing 12, 24, hours. Soleus morphological changes quantitated on histochemically...

Carbonic anhydrase (CA) activities were studied in soluble extracts and cryostat sections of skeletal muscles from prepubertal postpubertal rats. Acetazolamide inhibition was utilized to distinguish between the acetazolamide-sensitive (CA I II) acetazolamide-resistant III) forms enzyme. The studies indicated that fast-twitch oxidative-glycolytic muscle fibers contained both sensitive resistant CA. Acetazolamide-sensitive activity localized within fibers, axons, myelin, capillaries....

Abstract Prolonged exposure of humans to hypogravity causes weakening their skeletal muscles. This problem was studied in rats exposed for 7 days aboard Spacelab 3. Hindlimb muscles were harvested 12–16 hours postflight histochemical, biochemical, and ultrastructural analyses. The majority the soleus extensor digitorum longus fibers exhibited simple cell shrinkage. However, approximately 1% flight appeared necrotic. Flight muscle showed increased glycogen, lower subsarcolemmal staining...

Spacelab Life Sciences-1 and -2 provided skeletal muscles from rats dissected in flight for the first time 2 h to 14 days postflight. The permitted distinguishing of primary adaptations microgravity secondary reloading-induced alterations. In microgravity, adopted bipedal forelimb locomotion with hindlimbs relegated grasping activities. On landing day, body posture was abnormally low walking stilted at a rate one-third normal. adductor longus (AL) soleus exhibited decreased myofiber areas...

Previously we reported that, after 17-day bed rest unloading of 8 humans, soleus slow fibers atrophied and exhibited increased velocity shortening without fast myosin expression. The present ultrastructural study examined from the same muscle biopsies to determine whether decreased myofilament packing density accounted for observed speeding. Quantitation was by computer-assisted morphometry electron micrographs. Filament densities were normalized sarcomere length, because depends directly on...

Objective To evaluate peripheral nervous system function after chronic spinal cord injury (SCI). Design Case series. Setting Academic medical center. Participants Sixteen subjects (13 men, 3 women) with complete thoracic or cervical level SCI of 3‐32 years' duration since injury. Methods Clinical electrophysiology the lower extremities. Main Outcome Measurements Compound motor action potentials (CMAP), sensory nerve potentials, repetitive stimulation, concentric needle electromyography...

The effects of single 4-hr bouts continuous 30, 60, 120, and 800 Hz tail vibration (49 m/sec2, root mean squared) were compared to assess frequency-amplitude-related structural damage the ventral caudal artery. Amplitudes 3.9, 0.98, 0.24, 0.0055 mm, respectively. Vibrated, sham-vibrated, normal arteries processed for light electron microscopy. Curry rat model hand-arm (Curry et al. Muscle Nerve 2002;25:527–534) proved well-suited testing multiple frequencies. NFATc3 immunostaining, an early...

Slow type I fibers in soleus and fast white (IIa/IIx, IIx), red (IIa), slow (I) gastrocnemius were examined electron microscopically physiologically from pre- postflight biopsies of four astronauts the 17-day, Life Microgravity Sciences Spacelab Shuttle Transport System-78 mission. At 2.5-microm sarcomere length, thick filament density is approximately 1,012 filaments/microm(2) all fiber types unchanged by spaceflight. In preflight aldehyde-fixed biopsies, possess higher percentages...

Single skinned fibers from soleus and adductor longus (AL) muscles of weight-bearing control rats after 14-day hindlimb suspension unloading (HSU) were studied physiologically ultrastructurally to investigate how slow increase shortening velocity ( V 0 ) without fast myosin. We hypothesized that during HSU reduces densities thin filaments, generating wider myofilament separations decrease specific tension (kN/m 2 ). During HSU, plantarflexion shortened working length 23%. AL was unchanged....

Abstract Hand‐transmitted vibration from powered‐tools can cause peripheral vasospasm and neuropathy. A rat‐tail model was used to investigate whether the pattern of influenced type severity tissue damage. The tails awake rats were vibrated continuously or intermittently for a total 4 hours at 60 H Z , 49 m/s 2 . Nerves arteries harvested immediately 24 after treatment. Tails subjected intermittent showed transiently increased sensitivity thermal stimuli. Intermittent caused most nerve...