5.3 HIGH FIT OLDER ADULTS MAINTAIN A SIMILAR ENDOTHELIAL RESPONSE TO ACUTE INFLAMMATION AS YOUNGER ADULTS

Abstract

Inflammation is associated with an increased risk of cardiovascular events and reduced endothelial function. Higher cardiorespiratory fitness is associated with lower risk of cardiovascular events and improved vascular function. Whether fitness plays a role during acute inflammation is unknown. Purpose: Evaluate the role of fitness in the endothelial response to acute inflammation in younger (YA) and older (OA) adults. Methods: Acute inflammation was induced using influenza vaccine in 23 YA (12 male, 26 ± 4 yrs, 24.0 ± 3.5 kg/m2) and 60 OA (20 male, 65 ± 5 yrs, 27.8 ± 5.0 kg/m2). Blood pressure, flow-mediated dilation (FMD) and inflammatory markers were measured before and 24-hours post-vaccination. VO2peak was measured via a treadmill test. A VO2peak greater than age- and sex-associated 50th percentile according to the American College of Sports Medicine was defined as Fit. Results: Fit OA reduced FMD more than low fit OA (p = 0.02) 24 h post-vaccination. High and low fit YA similarly decreased FMD at 24 h (p = 0.66). YA and high fit OA had a similar reduction (relative %) in FMD (pz0.05). Regression analyses indicated no association between VO2peak and change in FMD (β = −0.01, p = 0.98) in YA, but a significant association existed in OA (β = −0.36, p = 0.04) after adjusting for age, sex, BMI and baseline FMD. YA-high fit YA-low fit OA-high fit OA-low fit n 14 9 16 43 VO2Max, ml/kg/min 48.4 (5.6)* 35.6 (4.9) 32.3 (4.2)* 21.9 (4.3) Baseline SBP 113 (13) 115 (13) 125 (14) 125 (14) Baseline PP 47 (8) 47 (11) 54 (10) 53 (11) Baseline FMD, % 12.4 (2.7) 11.6 (5.5) 7.5 (3.9)* 5.4 (2.5) Baseline CRP, mg/1 1.1 (0.7) 0.6 (0.6) 2.4 (3.3) 2.5 (2.2) Baseline IL-6, pg/ml 1.0 (0.7) 0.8 (0.5) 1.7 (1.4) 1.6 (1.1) Change SBP, mmHg −3 (6) 2 (8) −2 (9) −2 (11) Change PP, mmHg 2 (6) 5 (7) 0 (7) 0 (8) Change FMD, % −3.2 (4.1) −2.3 (5.5) −3.7 (3.8)* −0.2 (3.5) Change CRP, mg/l 1.0 (1.5) 0.9 (0.8) 1.1 (2.2) 0.9 (1.4) Change IL, pg/ml 1.0 (1.5) 1.6 (2.3) 0.8 (2.6) 0.4 (1.0) FMD: flow mediated dilation, CRP: C-reactive protein, IL-6: interleukin-6, SBP: systolic blood pressure, PP: pulse pressure *P < 00.5 vs. low-fit of same age category Conclusion: In OA, higher fitness is associated with a greater decrease in endothelial function during acute inflammation; high fit OA had a similar endothelial response compared to YA. This suggests intact reactivity of the vasculature to inflammatory stress in high fit OA, which may indicate a healthier vessel versus low fit OA.