Atrophy, disuse

B12. Brooks, J. E., Disuse atrophy of muscle. Intracellular electromyography. Arch. Neurol. (Chicago) 22, 27-30 (1970). 

Finally, there are interesting inverse associations between quadriceps strength and knee OA and disability. Quadriceps weakness, once thought to result from disuse atrophy in OA patients, may precede and even contribute to the development of OA, possibly through decreased knee stability. ... 

That disuse atrophy of muscle, as might arise by fixation of a leg in a splint or by pinning, may be a factor in causing a loss of body nitrogen following injury has been found to be so, but this is smaller than that arising from the actual damage done (C18, C19, S4). 

Note that resource availability in GSPT and thus in the ERM is potentially a function of time, allowing quantitative modeling of dynamic processes such as child development, aging, disuse atrophy, and rehabilitation. The notation further implies that availability of a given resource must be evaluated at a specific operating point, denoted as Q. At least conceptually, many parameters can be used to characterize... 

The dimensions of the residual limb vary with time (Fig. 33.5). The decrease in stump size results from the reduction of edema, wasting of soft tissues from prosthetic stresses, disuse atrophy of the residual limb musculature, and decrease in fatty tissue with overall weight loss. Initial prosthetic fitting often begins 1 to 2 weeks after surgery, following early compression wrapping. The time... 

This condition is usually found in the male child between the ages of 4 and 12. It is usually-unilateral, with ihe chief symptoms being pain in the hip and a marked limp. The pain may radiate into ihe groin and to the knee joint. There will be a limitation of abduction, extension, and internal rotation present ofthat hip. Disuse atrophy may be present in ihe upper thigh. 

Motor pathways in the brain consist of an upper motor neuron and a lower motor neuron. The upper motor neuron is located in the cerebral cortex and the lower motor neuron in the brain stem. A lesion of the upper motor neuron will result in muscle weakness or paralysis, with no muscle atrophy early and a disuse atrophy developing after a period of time. If a body part is bilaterally represented in the cortex, this would not be as noticeable. Increased muscle tone may be present along with increased tendon reflexes. The lower motor neuron is located in the brain stem. A lesion of the lower motor neuron is generally manifested as muscle weakness, flaccid paralysis, loss of reflexes, and an atrophy of the muscles. 

Hypoactivity ("disuse atrophy") is manifest as type-2 fiber atrophy... 

Brault JJ, Jespersen JG, Goldberg AL. (2010) Peroxisome proliferator-activated receptor gamma coactivator lalpha or Ibeta overexpression inhibits muscle protein degradation, induction of ubiquitin Ugases, and disuse atrophy. J Biol Chem 285, 19460-19471. 

Phillips SM, Glover BI, Rennie MJ. (2009) Alterations of protein turnover underlying disuse atrophy in human skeletal muscle. J Appl Physiol 107, 645-654. 

Chest wall compliance may be reduced in kyphoscoliosis, fibrothorax, or spinal cord injury and lung compliance may be reduced in pulmonary edema, pulmonary fibrosis, and acute respiratory distress syndrome (ARDS) and COPD in the presence of hyperinflation. Airway secretions or bronchoconstriction may contribute to increased airway resistance. Respiratory drive and muscle function may be compromised by anesthetics, sedation, coma, or hypercapnia, and muscle dysfunction may occur in the presence of malnutrition, hypophosphatemia, disuse atrophy, sepsis, myopathies, or limited oxygen delivery (9). The factors that led to a tracheostomy must be optimized prior to decannulation. 

Hespel, P, B. Op t Eijnde, M. Van Leemputte, B. Urso, P.L. Greenhaff, V. Labarque, S. Dymarkowski, P. Van Hecke, and E.A. Richter, Oral creatine supplementation facilitates the rehabilitation of disuse atrophy and alters the expression of muscle myogenic factors in humans. J Physiol, 536 (Pt 2) 625-633, 2001. 

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