Tag: muscle weakness

Human quadriceps strength and fatiguability in patients with post viral fatigue

Abstract:

Quadriceps isometric strength, activation and fatiguability were measured in 11 patients with symptoms of fatigue three months after glandular fever or a glandular fever-like illness.

Predicted normal and lower limits of normal muscle strength were calculated from height and age. These measures and the fatigue index were compared with a group of healthy students of similar age.

Two of the patients were unable to activate fully their muscles. After allowing for this inhibition the group mean (SD) strength was 104 (22%) of predicted. Although there was no significant difference in the fatigue index between the patients and the control group, there was a trend for the patients to show less fatigue than controls.

There was no difference in the muscle results for those patients who were found to have Epstein-Barr virus infections and those who did not. The feelings of weakness and fatigue experienced by the patients could not be explained by either physiological muscle fatigue or lack of effort.

 

Source: Rutherford OM, White PD. Human quadriceps strength and fatiguability in patients with post viral fatigue. J Neurol Neurosurg Psychiatry. 1991 Nov;54(11):961-4. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1014616/ (Full article)

 

Physiologic measurement of exercise and fatigue with special reference to chronic fatigue syndrome

Abstract:

Oxidative metabolism is the major source of energy for muscle activity, and maximal oxygen uptake (VO2max), the product of maximal cardiac output and maximal arteriovenous oxygen difference, indicates individual capacity for oxidative metabolism and performance of exercise by the large muscles.

Strength, a function of muscle cross-sectional area, motor-unit recruitment, and neuromuscular coordination, is the ability to develop force in a single, brief, maximal-effort voluntary contraction of rested muscle. Weakness is a diminished ability of rested muscle to exert maximal force. Fatigue is a loss of maximal force-generating capacity that develops during muscular activity, likely originates within muscle itself, and persists until muscle is fully recovered. Individual perception of motor effort can be determined with standardized rating scales.

These concepts are discussed in detail, their relevance to the pathophysiology of exercise in chronic fatigue syndrome is analyzed, and a general strategy of exercise evaluation pertinent to chronic fatigue syndrome is presented.

 

Source: Lewis SF, Haller RG. Physiologic measurement of exercise and fatigue with special reference to chronic fatigue syndrome. Rev Infect Dis. 1991 Jan-Feb;13 Suppl 1:S98-108. http://www.ncbi.nlm.nih.gov/pubmed/2020810