Title

The influence of hemostatic and inflammatory biomarkers on postexercise hypotension among men with high normal to stage 1 hypertension

Date of Completion

January 2006

Keywords

Health Sciences, Recreation

Degree

Ph.D.

Abstract

Exercise training reduces blood pressure (BP) and favorably affects other traditional and emerging cardiovascular disease (CVD) risk factors. Few studies have examined the effects of acute exercise on BP (i.e., postexercise hypotension) and emerging CVD risk factors. Therefore, this study investigated the influence of selected emerging biomarkers (i.e., fibrinogen, FIB; tissue plasminogen activator activity, t-PA; C-reactive protein, CRP) on BP following acute exercise at 40% (LITE) and 60% (MOD) maximum oxygen consumption. The purpose was to provide insight into possible mechanisms for postexercise hypotension. 50 men (43.8+1.3 yr) with high BP (145.3±1.5/85.9±1.1 mmHg) completed three randomized experiments: control seated rest and two cycle exercise sessions, i.e., LITE and MOD. FIB, t-PA, CRP and BP were measured before (baseline) and during the experiments. Volunteers left the laboratory wearing an ambulatory BP monitor. Pearson correlations and multivariate regression tested the relationships among FIB, t-PA, CRP and BP that included age and baseline BP as covariates. FIB, t-PA and CRP increased from baseline during exercise (p<0.05), with the increase in MOD greater than LITE (p<0.01). As FIB, t-PA and CRP increased, BP decreased over the course of 9 hr after LITE (p<0.05) but not MOD (p≥0.05). Exercise induced increases in FIB, t-PA and CRP explained approximately 10-15% of the BP response over this time, even in the presence of strong confounders (i.e., age and baseline BP). Reasons for these findings are not clear, however, it is probable that LITE results in relatively less circulating levels of pro-coagulant, pro-inflammatory, and vasoconstrictor factors and relatively greater levels of anti-coagulant, anti-inflammatory, and vasodilation factors compared to MOD. Consequently, this more favorable vasoconstriction-vasodilation and inflammatory-hemostatic balance may result in lower total peripheral resistance and subsequently lower BP with LITE than MOD. In conclusion, exercise induced increases in FIB, t-PA, and CRP explained a portion of the BP response over the course of 9 hr after LITE among men with high BP. Measuring exercise induced hemostatic and inflammatory biomarkers may assist in the characterization of people who lower their BP with exercise so that tailored therapeutic interventions and prevention strategies can be prescribed for those with hypertension.^