Validation of an adjustment equation for the burst superimposition technique in subjects post-stroke

Abstract

Introduction: Deficits in voluntary force generation may be due to incomplete activation or decreased maximum force-generating ability (MFGA) of the targeted muscle. The validity of techniques used to measure MFGA in individuals post-stroke has not been assessed. The objective of this study was to determine the reliability of the MFGA predicted using an adjusted burst superimposition method within a post-stroke population.

Methods: Differences in paretic-side plantar flexor muscle MFGA between 2 trials was calculated using the standard and adjusted burst superimposition technique for 17 individuals post-stroke (15 men, 58.7 ± 10 years of age, ≥6 months post-stroke) to assess reliability of the techniques.

Results: The adjusted measurement was shown to be more reliable (P = 0.03), especially when volitional effort differed by >40 N.

Conclusions: Reliable measurement of the MFGA in individuals who have sustained a stroke is of clinical importance. These results suggest that the adjusted burst superimposition method may be useful when performing multiple measurements of muscle performance.

Copyright © 2012 Wiley Periodicals, Inc.

Figures

Figure 1

(A) Volitional forces (Fvol) and predicted maximum force generating abilities (MFGA) for 2 trials of the burst superimposition test with (MFGAadj) and without (MFGAburst) adjustment for 17 individuals post-stroke. (B) Difference between MGFA predictions versus differences in voluntary forces (ΔFvol) for 2 trials of the burst superimposition test. The adjusted MFGA value is more reliable (closer to zero) for all individuals with ΔFvol greater than 40 N.