Characterising the Blood Pressure Response to Physical Counterpressure
Manoeuvres Using Surface Electromyography in Adults with Long Covid
Abstract
Objective: Orthostatic intolerance (OI) is common in Long Covid.
Physical counterpressure manoeuvres (PCM) may improve OI in other
disorders. We characterised the blood pressure-rising effect of PCM
using surface electromyography (sEMG) and investigated its association
with fatigue in adults with Long Covid. Methods: Participants performed
an active stand with beat-to-beat hemodynamic monitoring and sEMG of
both thighs, including PCM at 3-minutes post-stand. Multivariable linear
regression investigated the association between change in systolic blood
pressure (SBP) and change in normalised root mean square (RMS) of sEMG
amplitude, controlling for confounders including the Chalder Fatigue
Scale (CFQ). Results: In 90 participants (mean age 46), mean SBP rise
with PCM was 13.7 (SD 9.0) mmHg. In regression, SBP change was
significantly, directly associated with change in RMS sEMG (β=0.25, 95%
CI 0.07–0.43, P=0.007); however, CFQ was not significant.
Discussion/Conclusion: PCM measured by sEMG augmented SBP without the
influence of fatigue.