(953.19) Objectively Measured Vigorous-Intensity Physical Activity is Related to Endothelial Function in Midlife and Older Men but not in Estrogen-Deficient Postmenopausal Women

Poster Board Number: E567

Grace Maurer (University of Colorado Boulder), Kaitlin Freeberg (University of Colorado Boulder), Douglas Seals (University of Colorado Boulder), Daniel Craighead (University of Colorado Boulder)

Background. Aerobic exercise training is consistently associated with enhanced vascular endothelial function via suppression of oxidative stress in midlife/older (ML/O; 50 years) men but not in estrogen-deficient postmenopausal women (E-PMW). It is unclear if chronic physical activity (PA) patterns assessed under free-living conditions, including sedentary behavior and vigorous exercise, are related to endothelial function among ML/O men or E-PMW. We investigated if objectively measured PA patterns were associated with endothelial function in ML/O adults and the potential mechanisms involved. 

Methods. 172 ML/O adults were included for analysis (67 ± 7 years; 85M/87W). Endothelium-dependent dilation was assessed via brachial artery flow-mediated dilation (FMDBA), a bioassay of endothelial function. PA was assessed over 3-7 days via wrist-worn accelerometers (GENEactiv), which measured sedentary time and light, moderate, and vigorous activity. The relations between endothelial function and PA were examined using simple and stepwise linear regression. Multiple linear regression was used to examine the correlation between endothelial function and PA when controlling for conventional cardiovascular disease risk factors. Plasma oxidized low-density lipoprotein (OxLDL) concentrations and total antioxidant status were used as markers of oxidative stress and antioxidant defenses, respectively. Interleukin-6, tumor necrosis factor-α, and C-reactive protein concentrations were examined to assess chronic low-grade inflammation. Mediation analysis was used to determine the potential for changes in oxidative stress, antioxidant defenses, and inflammation as mechanisms mediating the relation between PA and endothelial function. 

Results. In the entire cohort of subjects, FMDBA was negatively associated with sedentary time (R2=0.04; p=0.01), not associated with light PA (R2=0.02; p=0.09), and positively associated with moderate (R2=0.03; p=0.04) and vigorous (R2=0.06; plt;0.01) PA. Only sedentary time (R2=0.06; p=0.02) and vigorous PA (R2=0.11; plt;0.01) were associated with FMDBA in ML/O men. No PA parameters were associated with FMDBA in E-PMW (all pgt;0.05). Stepwise linear regression revealed vigorous PA primarily mediated the effects of PA on FMDBA in ML/O men (R2=0.10; plt;0.01). When controlling for age, blood pressure, body mass index, triglycerides, high-density lipoprotein, low-density lipoprotein, and fasting glucose, vigorous PA independently predicted FMDBA in ML/O men (R2=0.05; p=0.05) but not in E-PMW (R2=0.03; p=0.18). Plasma OxLDL concentrations mediated 13.5% of the group effect of vigorous PA on FMDBA (plt;0.01); no other plasma markers had a mediating effect (all pgt;0.05).Conclusions. Objectively measured PA, primarily vigorous PA, is positively associated with endothelial function in ML/O men but not in E-PMW. This relation is mediated, in part, by oxidative stress. These associations are consistent with findings that aerobic exercise training does not improve endothelial function in E-PMW. Alternative strategies to improve endothelial function in E-PMW are needed.

K01HL153326, F31HL154782