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Muscle weakness is a lack of muscle strength. Its causes are many and can be divided into conditions that have either true or perceived muscle weakness. True muscle weakness is a primary symptom of a variety of skeletal muscle diseases, including muscular dystrophy and inflammatory myopathy.
1970: Smith, Watson, and Topper developed a mean stress correction model, where the fatigue damage in a cycle is determined by the product of the maximum stress and strain amplitude. [ 20 ] 1970: W. Elber elucidates the mechanisms and importance of crack closure in slowing the growth of a fatigue crack due to the wedging effect of plastic ...
Neurogenic claudication commonly describes pain, weakness, fatigue, tingling, heaviness and paresthesias that extend into the lower extremities. [9] These symptoms may involve only one leg, but they usually involve both. Leg pain is usually more significant than back pain in individuals who have both. [12]
Muscle fatigue may be due to precise molecular changes that occur in vivo with sustained exercise. It has been found that the ryanodine receptor present in skeletal muscle undergoes a conformational change during exercise, resulting in "leaky" channels that are deficient in calcium release.
Δε e /2 is the elastic strain amplitude; 2N is the number of reversals to failure (N cycles); ε f ' is an empirical constant known as the fatigue ductility coefficient defined by the strain intercept at 2N =1; c is an empirical constant known as the fatigue ductility exponent, commonly ranging from -0.5 to -0.7. Small c results in long ...
Central nervous system fatigue, or central fatigue, is a form of fatigue that is associated with changes in the synaptic concentration of neurotransmitters within the central nervous system (CNS; including the brain and spinal cord) which affects exercise performance and muscle function and cannot be explained by peripheral factors that affect muscle function.
Weakness is a symptom of many different medical conditions. [1] The causes are many and can be divided into conditions that have true or perceived muscle weakness. True muscle weakness is a primary symptom of a variety of skeletal muscle diseases, including muscular dystrophy and inflammatory myopathy.
The general trend given by the Goodman relation is one of decreasing fatigue life with increasing mean stress for a given level of alternating stress. The relation can be plotted to determine the safe cyclic loading of a part; if the coordinate given by the mean stress and the alternating stress lies under the curve given by the relation, then ...