Voluntary Activation Failure in Myositis Patients
Author Information
Author(s): Catherine B. Molloy, Ahmed O. Al-Omar, Kathryn T. Edge, Robert G. Cooper
Primary Institution: University of Manchester Rheumatic Disease Centre
Hypothesis
Can voluntary activation failure contribute to the persisting weakness observed in some patients with treated idiopathic inflammatory myositis?
Conclusion
The study found that voluntary activation failure does contribute to quadriceps weakness in some myositis patients.
Supporting Evidence
- Six of the 14 'weak' patients exhibited interpolated twitches during electrical stimulation.
- Mass-normalised MVCs of female patients were significantly smaller than those of normal subjects (p < 0.001).
- Only one of the six 'not weak' patients exhibited interpolated twitches.
Takeaway
Some patients with myositis can't fully activate their muscles, which makes them weaker even after treatment.
Methodology
This cross-sectional observational study measured maximum voluntary contractions of the quadriceps in myositis patients and normal subjects, using the twitch interpolation technique to assess muscle activation.
Potential Biases
Potential bias due to the exclusion of patients with current quadriceps myalgia and knee joint pathologies.
Limitations
The study had a small sample size and included age differences between patients and normal subjects.
Participant Demographics
20 patients (5 males, 15 females) with a mean age of 53 years and 102 normal subjects (44 males, 58 females) with a mean age of 32 years.
Statistical Information
P-Value
p < 0.001
Statistical Significance
p < 0.001
Digital Object Identifier (DOI)
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