Key result
A history of polio was associated with significantly reduced quadriceps strength, cross-sectional area, and relaxation rate compared to controls, with voluntary activation further reduced in PPS.
Why the study?
Are quadriceps strength, cross-sectional area, voluntary activation, and relaxation rate altered in subjects with a history of polio and postpoliomyelitis syndrome compared to controls?
Cross-Sectional (n=61)
Are quadriceps strength, cross-sectional area, voluntary activation, and relaxation rate altered in subjects with a history of polio and postpoliomyelitis syndrome compared to controls?
Muscle weakness and functional decline in postpoliomyelitis syndrome may be driven by an increasing inability to activate muscles in addition to muscle fiber loss.
May implicate activation deficits in PPS weakness beyond atrophy; hypothesis-generating for interventional studies.
Quadriceps strength, maximal anatomical cross-sectional area (CSA), maximal voluntary activation (MVA), and maximal relaxation rate (MRR) were studied in 48 subjects with a past history of polio, 26 with and 22 without postpoliomyelitis syndrome (PPS), and in 13 control subjects. It was also investigated whether, apart from CSA, MVA and MRR were determinants of muscle strength. Polio subjects had significantly less strength, CSA, and MRR in the more-affected quadriceps than control subjects. MVA was reduced in 18 polio subjects and normal in all controls. PPS subjects differed from non-PPS subjects only in that the MVA of the more-affected quadriceps was significantly lower. Both CSA and MVA were found to be associated with muscle strength. Quadriceps strength in polio subjects was dependent not only on muscle mass, but also on the ability to activate the muscles. Since impaired activation was more pronounced in PPS subjects, the new muscle weakness and functional decline in PPS may be due not only to a gradual loss of muscle fibers, but also to an increasing inability to activate the muscles.
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Beelen et al. (2003) conducted a cross-sectional in Past history of polio (n=61). Past history of polio and postpoliomyelitis syndrome vs. Healthy controls and polio subjects without postpoliomyelitis syndrome was evaluated on Quadriceps strength, maximal anatomical cross-sectional area (CSA), maximal voluntary activation (MVA), and maximal relaxation rate (MRR). A history of polio was associated with significantly reduced quadriceps strength, cross-sectional area, and relaxation rate compared to controls, with voluntary activation further reduced in PPS.
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