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

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 = post - exercise - pre - exercise ${A}_{1}=\text{post}{\rm{ \mbox{-} }}\text{exercise}-\text{pre}{\rm{ \mbox{-} }}\text{exercise}$ ); ( A 2 = post - exercise - post - CTL ) $({A}_{2}=\text{post}{\rm{ \mbox{-} }}\text{exercise}-\text{post}{\rm{ \mbox{-} }}\text{CTL})$ ; A 3 = ( 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).

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 (ICC2,1 ) 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.