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Faculty Mentor

James F. Hokanson

Abstract

During exercise, lower leg muscle activation has been shown to increase venous return, exercise cardiac output, and arterial blood pressure (BP). Here we investigate BP at rest, with an increase in lower body pressure by unweighting volunteers in a lower body positive pressure treadmill (LBPP-TM). The purpose of this study was twofold; to determine if BP changes while standing over five-minute stages in response to four conditions. Nine participants (21.3±1.8 years) stood in a LBPP-TM in the following ordered conditions: 100%BWset (no unweighting, control), 70%BWset, 35%BWset, and 90%BWset (35%BWset is the greatest unweighted condition). A SunTech® automatic BP cuff measured systolic and diastolic BP (SBP and DBP, respectively). SBP and DBP was measured once during 100%BWset and averaged over the five-minute stages during 70%BWset, 35%BWset, and 90%BWset. A portable Davis Vantage weather station inside the chamber measured chamber air pressure (CAP). Repeated measures analysis of variance evidenced significant differences in only SBP (p = 0.006) at 100%BWset (no unweighting) and 90%BWset (129±11 mmHg and 120±8 mmHg, respectively). DBP did not show any significant differences across conditions (ps > 0.091). CAP at 100%BWset (767.5±4.9 mmHg) was lower compared to 70%BWset (780.0±3.0 mmHg), 35%BWset (793.5±3.0 mmHg), and 90%BWset (776.4±7.0 mmHg) (p<0.001, p<0.001, and p=0.001, respectively). 35%BWset CAP was also higher than 70%BWset and 90%BWset (ps<0.001 for both), but 70%BWset and 90%BWset CAPs were not different (p = 0.486). The initial findings suggest a quick reduction in CAP (35%BWset to 90%BWset) may decrease SBP below starting levels at 100%BWset. Though the sample consists of healthy, young adults and there was only a 9.0 mmHg decrease in SBP, individuals who are intolerant to SBP changes or older adults may need a slower reduction in CAP from highly unweighted conditions to account for SBP changes as they return to baseline CAP.

Publication Date

4-2022

Document Type

Book

Keywords

Kinesiology, blood pressure, lower body positive pressure treadmill, LBPP-TM, Transformations

Disciplines

Kinesiotherapy

Blood Pressure Responses during Three Unweighted Conditions in a Lower Body Positive Pressure Treadmill

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