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

Abstract

Background

This 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., ($A_1=\text{post}-\text{exercise}-\text{pre}-\text{exercise}$); $(A_2=\text{post}-\text{exercise}-\text{post}-\text{CTL})$; $A_3=\left(\text{post}-\text{exercise}-\text{pre}-\text{exercise}\right)-\left(\text{post}-\text{CTL}-\text{pre}-\text{CTL}\right)]$ 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).

Methods

Seven 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.

Results

The two-way random intraclass correlation coefficient for single measurements (ICC_2,1) ranges for SBP were: A₁: 0.580−0.829, A₂: 0.937−0.994, A₃: 0.278−0.774; for DBP: A₁: 0.497−0.916, A₂: 0.133−0.969, A₃: 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.

Conclusions

The 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.