Advancing age increases the risk of cardiovascular disease (CVD), largely due to the development of systemic vascular endothelial dysfunction and stiffening of the large elastic arteries. This thesis included three studies, which investigated the independent and combined effects of exercise and short-term folic acid (FA) supplementation on cardiovascular responses in healthy middle-aged men (MM) and postmenopausal women (PMW). Young men (YM) and premenopausal women (PreM) were studied under the same experimental conditions to ascertain responses in the healthy arterial system. The methodology included pulse wave analysis, venous occlusion plethysmography and flow mediated dilation (FMD) to assess indexes of aortic wave reflection (AWRi), calf blood flow (CBF) and brachial artery endothelium-dependent vasodilation, respectively. The first experimental study (Chapter 4) explored the vascular effects of short-term FA supplementation on endothelial function and arterial stiffness in age-matched healthy middle-aged (56±1 years; mean±SEM) PMW (n=13) and MM (n=14), and young (26±1 years) PreM (n=12) and YM (n=14). Brachial systolic, diastolic, mean arterial blood pressure (BP), pulse pressure (SBPb, DBPb, MAPb, PPb; mmHg) and pulse pressure amplification were recorded. Flow-mediated dilation (FMD) was assessed using ultrasound methods. Pulse wave analysis (applanation tonometry) was used to determine central (aortic) BP (BPc) and indexes of aortic wave reflection (AWRi), including augmentation pressure (AP; mmHg), augmentation index (AIx; %), and AIx corrected for heart rate (AIx75; %). Measures were recorded before and after 4-weeks of FA supplementation (5 mg/day). Plasma nitrite, and asymmetric dimethylarginine (ADMA), an inhibitor of NO synthesis, were also analysed. Before FA, in PMW and MM, all AWRi were higher (p<0.05) in PMW yet SBPb, DBPb, MAPb, DBPc, MAPc and PPA were lower (p<0.05). In contrast SBPc did not differ (p > 0.05) between groups. In PMW, ADMA associated positively (p<0.05) with AWRi, and nitrite inversely (p<0.05) with central and peripheral SBP and MAP. In MM, nitrite was positively associated (p<0.05) with central and peripheral PP, and ADMA inversely (p<0.05) with central and peripheral SBP, DBP, and MAP. Post-FA, AIx, AIx75, nitrite and ADMA remained unchanged (p > 0.05) in MM and PMW, yet AP, MAPc, and central and brachial SBP and PP were reduced (p<0.05) in both groups. These BP changes associated inversely with changes in nitrite (p<0.05). All AWRi were higher (p<0.05) in older versus younger groups both before and after FA, with values being higher (p<0.05) in PreM versus YM. Excluding PPc which was reduced in YM, FA did not alter AWRi or BP in young men and women. This study demonstrated that FA may be an effective nutraceutical strategy to improve endothelial function, reduce large artery stiffness, and attenuate the age-associated development of hypertension in both men and women. The second experimental study (Chapter 5) investigated the effects of an acute bout of aerobic exercise on vascular function in the lower limb of untrained (PMWun; n=13) and habitually exercise trained (PMWtr; n=10) PMW. PreM (n=14) were also included as a healthy young comparator group. Using strain-gauge plethysmography, resting and peak calf blood flow (CBFr and CBFpk, respectively) and vascular resistance (CVRr and CVRpk) were assessed before and after reactive hyperaemia, and before and one-hour after 45 minutes of brisk walking at 60% V̇O_2peak. Blood samples were analysed for nitrite, triglycerides, low- and high-density lipoprotein cholesterol (LDLc and HDLc), insulin and glucose. Pre-exercise, CBFpk was higher (p<0.05) and CVRpk and triglycerides lower (p<0.05) in PMWtr. CBFpk was inversely and CVRpk positively associated (p<0.05) with insulin in PMWtr. In PMWun, CBFpk correlated inversely (p<0.05) with glucose, and positively (p<0.05) with HDLc. CVRpk also correlated positively with LDLc and triglycerides (p<0.05). Post-exercise, in PMW, resting and peak CBF were increased (p<0.05) and CVR decreased (p<0.05), yet CBFpk remained higher (p<0.05) and CVRpk lower (p<0.05) in PMWtr. In PreM, pre- and post-exercise CBF and CVR responses did not differ (p > 0.05) from PMWun, except for CVRr pre-exercise, which was lower in PreM. This study demonstrated that compared with untrained PMW, habitually trained PMW demonstrate augmented CBFpk both before and after exercise. Despite similar levels of cardiometabolic markers, CBFpk was inversely associated with insulin in PMWtr, yet was inversely associated with glucose and pro-atherogenic lipids in PMWun. Aerobic exercise training may favourably modulate the vascular effects of circulating cardiometabolic markers in PMW. The third experimental study (Chapter 6) investigated the independent and combined effects of exercise and FA supplementation on brachial artery endothelial function in habitually exercise trained (PMWtr; n=12) and untrained (PMWun; n=12) PMW, and healthy young PreM (n=12). Flow-mediated dilation (FMD) was assessed using ultrasound methods before and 60-min after an acute bout of dynamic exercise (45- min, 60% V̇O_2peak), before and after 4-weeks of FA supplementation (5 mg/day). Blood samples were analysed for plasma nitrite, and asymmetric dimethylarginine (ADMA), an inhibitor of NO synthesis. Baseline FMD% did not differ (p > 0.05) between PMWun and PMWtr (mean±SEM; 3.53±0.33% and 4.21±0.40%, respectively) but was higher (p<0.01) in PreM (8.77±0.96%). In all groups, FMD% was unchanged (p > 0.05) 60-min after exercise. FA augmented FMD% in PMWun only (4.65±0.50%; p<0.05) in association with a reduction in systolic blood pressure. Exercise combined with FA did not elicit additive effects to FMD% (p > 0.05) in any group. ADMA and nitrite levels were not associated with FMD% in PMW and were unaltered by FA. This study demonstrated that FMD in trained PMW is neither augmented post-exercise nor is it improved with short-term FA. In contrast, FA, but not exercise, improved FMD in untrained PMW. These findings suggest vascular responsiveness to exercise may be blunted in estrogen deficient PMW, regardless of training status, and that FA does not restore vascular adaptations to habitual exercise training. Collectively, these three studies demonstrate that exercise and FA are able to exert favourable cardiovascular effects in healthy middle-aged adults. Whilst the clinical implications of these findings are unclear, it is possible that through attenuating the development of arterial dysfunction, exercise and FA may play a role in reducing CVD risk.