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  • Nonuniform loss of muscle strength and atrophy during bed rest [Elektronski vir] : a systematic review
    Marušič, Uroš ...
    Muscle atrophy and decline in muscle strength appear very rapidly with prolonged disuse or mechanical unloading after acute hospitalization or experimental bed rest. The current study analyzed data ... from short-, medium-, and long-term bed rest (5-120 days) in a pooled sample of 318 healthy adults and modeled the mathematical relationship between muscle strength decline and atrophy. The results show a logarithmic disuse-induced loss of strength and muscle atrophy of the weight-bearing knee extensor muscles. The greatest rate of muscle strength decline and atrophy occurred in the earliest stages of bed rest, plateauing later, and likely contributed to the rapid neuromuscular loss of function in the early period. In addition, during the first two weeks of bed rest, muscle strength decline is much faster than muscle atrophy: on day 5, the ratio of muscle atrophy to strength decline as a function of bed rest duration is 4.2, falls to 2.4 on day 14, and stabilizes to a value of 1.9 after about 35 days of bed rest. Positive regression revealed that approximately 79% of the muscle strength loss may be explained by muscle atrophy, while the remaining is most likely due to alterations in single fiber mechanical properties, excitation-contraction coupling, fiber architecture, tendon stiffness, muscle denervation, neuromuscular junction damage and supraspinal changes. Future studies should focus on neural factors as well as muscular factors independent of atrophy (single fibre excitability and mechanical properties, architectural factors) and on the role of extracellular matrix changes. Bed rest results in non-uniform loss of isometric muscle strength and atrophy over time, where the magnitude of change was greater for muscle strength than for atrophy. Future research should focus on the loss of muscle function and the underlying mechanisms, which will aid in the development of countermeasures to mitigate or prevent the decline in neuromuscular efficiency.
    Source: Journal of applied physiology. - ISSN 1522-1601 (Vol. 131, iss. 1, Jul. 2021, str. 194-206)
    Type of material - e-article ; adult, serious
    Publish date - 2021
    Language - english
    COBISS.SI-ID - 55379715

    Link(s):

    https://journals.physiology.org/doi/abs/10.1152/japplphysiol.00363.2020
    DOI

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