Is postexercise hypotension a method-dependent phenomenon in chronic stroke? A crossover randomized controlled trial

BackgroundThis study assessed the reproducibility of postexercise hypotension (PEH) detection after two bouts of mixed circuit training (MCT) using three approaches that accounts the pre-exercise values and/or a control session (CTL) to calculate PEH [i.e., (A1=post-exercise-pre-exercise ${A}_{1}=\text{post}{\rm{ \mbox{-} }}\text{exercise}-\text{pre}{\rm{ \mbox{-} }}\text{exercise}$); (A2=post-exercise-post-CTL) $({A}_{2}=\text{post}{\rm{ \mbox{-} }}\text{exercise}-\text{post}{\rm{ \mbox{-} }}\text{CTL})$; A3=(post-exercise-pre-exercise)-(post-CTL-pre-CTL)] ${A}_{3}=(\text{post}{\rm{ \mbox{-} }}\text{exercise}-\text{pre}{\rm{ \mbox{-} }}\text{exercise})-(\text{post}{\rm{ \mbox{-} }}\text{CTL}-\text{pre}{\rm{ \mbox{-} }}\text{CTL})]$ in chronic stroke (i.e., >= 6 months poststroke). The proportion of PEH responders determined using different cut-off values for PEH was also compared (4 mmHg vs. minimal detectable difference). MethodsSeven participants (age: 56 +/- 12 years; time post-stroke: 91 +/- 55 months) performed two bouts of MCT and a CTL. The MCT involved 10 exercises with 3 sets of 15-repetition maximum, with each set interspersed with 45 s of walking. The systolic (SBP) and diastolic (DBP) blood pressures were assessed 10-min before and every 10-min along 40-min after CTL and MCT. ResultsThe two-way random intraclass correlation coefficient for single measurements (ICC2,1) ranges for SBP were: A(1): 0.580-0.829, A(2): 0.937-0.994, A(3): 0.278-0.774; for DBP: A(1): 0.497-0.916, A(2): 0.133-0.969, A(3): 0.175-0.930. The proportion of PEH responders detected using 4 mmHg or the minimal detectable difference as cut-off values was not different in 97% of analyses (p > 0.05), and higher when using 4 mmHg in 3% of analyses (p = 0.031). The standard error of measurement was >= 4 mmHg in 47% of analyses for SBP, and 40% for DBP. ConclusionsThe most reliable approach for determining PEH in chronic stroke was to subtract the postexercise from the post-CTL values. The proportion of PEH responders was not affected by the cut-off values applied.