Human fiber size and enzymatic properties after 5 and 11 days of spaceflight

Edgerton, V. Reggie; Zhou, Ming; Ohira, Yoshinobu; Klitgaard, Henrik; Bian, Jiang; Bell, Gordon J.; Harris, Barbara J.; Saltin, Bengt; Gollnick, Paul; Roy, Roland R.

doi:10.1152/jappl.1995.78.5.1733

Cited by 284 publications

(251 citation statements)

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“…The ex-pression of IId MHC (most likely analogous to IIx) has also been observed in the rat soleus of 21-and 28-d suspended rats [67]. A similar tendency in fiber type transformation was also seen in the human vastus lateralis muscle after 11 d of spaceflight [77,78] and in the soleus after 4 months of bedrest associated with fiber atrophy [79,80].…”

Section: Fiber Phenotypementioning

confidence: 67%

Neuromuscular Adaptation to Microgravity Environment.

Ohira

2000

JJP

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The pattern of muscle activity influences the morphological, metabolic, and contractile properties of skeletal muscles. For example, the metabolic capacity of muscles is affected specifically by the type of exercise training [1][2][3]. Increased activity or over-loading by removing the synergists causes a compensatory hypertrophy [4][5][6][7][8][9][10][11]. Hypertrophy is also induced by the stretching of matured muscles in vivo [12,13] and cultured myotubes and fibroblasts [14][15][16][17]. Exercise-induced metabolic adaptation of muscles is lost when exercise training is stopped [18]. Further, muscle atrophy is induced by denervation [10,19], spinal cord transection [20], joint immobilization [21][22][23], tenotomy [24,25], spaceflight [26][27][28][29], and/or hindlimb suspension [29][30][31][32]. Most of these models are generally presumed to be models of reduced neuromuscular activity. But the level of use may not be the only factor involved in the atrophic process.There is a close association in the physiological, biochemical, and morphological properties between a motoneuron and the muscle fibers it innervates [1]. Studies to support this view are those in which chronic electrical stimulation at low frequency (1-10 Hz) changes the properties of fast-twitch muscles toward those of slow-twitch muscles [33][34][35][36][37][38].Some of the characteristics of muscle fibers are also altered following cross-innervation [39][40][41][42]. Buller et al. [40] suggested that the neural influence on muscle could be due to neurotrophic effect as well as via nerve impulses. Muscular Responses to Gravitational Unloading Morphological propertiesGravitational unloading by exposure to weightlessness [26][27][28][29][43][44][45][46][47] and/or its simulation model, hindlimb suspension [29][30][31][32][48][49][50][51][52][53][54][55][56], causes rapid atrophy in muscles, such as soleus and adductor longus, that are composed predominantly of slow fibers. The cross-sectional areas (CSAs) of both slow-and fasttwitch fibers of rats were less after 14 d of spaceflight and hindlimb suspension than those in the agematched controls [29]. But the degree of atrophy was greater in slow-than fast-twitch fibers [28,29]. Therefore, muscles composed of predominantly slow fibers are more susceptible to atrophy [26,28, 47]. The weights of fast-twitch ankle dorsi-flexors, such as the tibialis anterior (TA) and extensor digitorum longus (EDL), are also generally less after unloading than those of age-matched controls [31, 57]. But these were Japanese Journal of Physiology, 50, 303-314, 2000 Key words: atrophy, fiber-type transformation, contractile properties, neural responses, microgravity.Abstract: Morphological and/or functional characteristics of skeletal muscles have a greater adaptability in response to changes in environmental stimuli. For example, an atrophy associated with a shift of fiber characteristics toward fast-twitch type is a common adaptation of antigravity muscle to a microgravity environment. Neuromuscular responses and ...

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Section: Fiber Phenotypementioning

confidence: 67%

Neuromuscular Adaptation to Microgravity Environment.

Ohira

2000

JJP

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“…LeBlanc et al 75 showed a 6% decrease in muscle volume following an 8-day spaceflight, whereas 6 months of spaceflight seems to result in a 13-17% decrease in muscle mass. 76,77 Following an 11-day human spaceflight, Edgerton et al 78 observed a significant decline in Short-term space flight (17 days) was found to reduce specific tension of soleus muscle fibers. 80 Although human data from Skylab and Mir suggest that leg extensors atrophy and loose peak force faster than flexors, when flight duration is long enough (4200 days) both groups of muscles show similar declines of B30 % in isokinetic strength.…”

Section: Muscle Atrophymentioning

confidence: 99%

“…Furthermore, lipid droplets (white spheres) were more frequent postflight, accompanied by partially lost alignment of sarcomeres of adjacent myofibrils. 78 It is important to note similarities in atrophy and loss of sarcomere alignment between individuals with SCI and astronauts postflight. Although both SCI and spaceflight lead to a decrease in muscle mass, a fundamental difference is believed to exist between disuse and denervation atrophy.…”

Section: Physiological Consequences Of Sci and Microgravitymentioning

confidence: 99%

Challenges, concerns and common problems: physiological consequences of spinal cord injury and microgravity

et al. 2010

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Introduction: Similarities between the clinical presentation of individuals living with spinal cord injury (SCI) and astronauts are remarkable, and may be of great interest to clinicians and scientists alike. Objectives: The primary purpose of this review is to outline the manner in which cardiovascular, musculoskeletal, renal, immune and sensory motor systems are affected by microgravity and SCI. Methods: A comprehensive review of the literature was conducted (using PubMed) to evaluate the hallmark symptoms seen after spaceflight and SCI. This literature was then examined critically to determine symptoms common to both populations. Results: Both SCI and prolonged microgravity exposure are associated with marked deteriorations in various physiological functions. Atrophy in muscle and bone, cardiovascular disturbances, and alterations in renal, immune and sensory motor systems are conditions commonly observed not only in individuals with SCI, but also in those who experience prolonged gravity unloading. Conclusion: The preponderance of data indicates that similar physiological changes occur in both SCI and prolonged space flight. These findings have important implications for future research in SCI and prolonged space flight.

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“…1,27,62,64,69,78,84 For example, inactivity induces substantial atrophy in muscles that play an antigravity, postural role. The antigravity, predominantly slow-twitch type I muscles, such as the soleus, atrophy more than primarily fasttwitch type II muscles and extensor muscles are more affected than flexors.…”

Section: Inactivity and Muscle Massmentioning

confidence: 99%

Skeletal Muscle Adaptations with Age, Inactivity, and Therapeutic Exercise

Thompson¹

2002

J Orthop Sports Phys Ther

104

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One of the remarkable features of skeletal muscle is its adaptability. Skeletal muscle adaptations are characterized by modifications of morphological, biochemical, and molecular variables that alter the functional attributes of specific skeletal muscle fiber types. Skeletal muscle adaptation is diverse and the magnitude of change is dependent on many factors, such as activity pattern, age, and muscle fiber type composition. The adaptation of skeletal muscle in the adult population is well described. In contrast, the adaptation of skeletal muscle in the older population is less documented, especially in the area of inactivity-induced alterations. Age-related changes in skeletal muscle may play a significant role in the magnitude of change with inactivity and influence the rehabilitation process for the older adult.A consistent feature of age and inactivity is limb muscle atrophy and the loss of peak force and power. Differences exist in the rate and mechanisms of muscle wasting and in the susceptibility of a given fiber type to atrophy. Most likely, the rapid muscle wasting might be in part due to a decrease in protein synthesis coupled with an increased degradation. Besides the quantitative change in muscle mass, age and inactivity induce important qualitative changes in the structure of key skeletal muscle proteins that are manifested in alterations in contractile properties.Therefore, the purpose of this clinical commentary is to identify the major effects of age and inactivity on skeletal muscle structure and function, and discuss potential therapeutic interventions. Special emphasis will be placed on how alterations in muscle structure affect function and on the cellular and molecular mechanisms of the age-related and inactivity-induced muscle changes.

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Human fiber size and enzymatic properties after 5 and 11 days of spaceflight

Cited by 284 publications

References 0 publications

Neuromuscular Adaptation to Microgravity Environment.

Neuromuscular Adaptation to Microgravity Environment.

Challenges, concerns and common problems: physiological consequences of spinal cord injury and microgravity

Skeletal Muscle Adaptations with Age, Inactivity, and Therapeutic Exercise

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