Cardiovascular disease (CVD) is the leading cause of death globally, representing 31% of all deaths in 2015. A key risk factor for CVD is physical inactivity, the fourth highest risk factor for all-cause mortality globally (WorldHealthOrganization, 2009). In the vasculature, blood exerts a force upon the endothelial lining of the vessel recorded as wall shear stress (WSS). The pattern, magnitude and volume of WSS can determine the phenotype of endothelial cells (ECs). High WSS with laminar flow is associated with an anti-inflammatory phenotype, whereas low and oscillatory WSS is associated with a pro-inflammatory phenotype. Exercise impacts WSS through increased cardiac output and thus diverse exercise protocols may have differential benefits for the health of the endothelium. We explored the impact of exercise upon WSS profiles in the aortic arch. Ten healthy participants lay supine in a 1.5T MRI scanner for 15 minutes to assess resting WSS before commencing a continuous exercise protocol for 15 min at 55% heart rate maximum. Participants exercised on a supine cycle ergometer and images of the aortic arch were acquired throughout. Average spatial WSS was recorded in the aortic arch from the ascending to descending aorta in eight planes each divided into spatial segments. Results were examined across plane and segment for total WSS (tWSS), circumferential WSS (cWSS) and axial WSS (aWSS). At rest mean ± SD tWSS and aWSS increased sequentially from the ascending (planes 1-5) (1058.69±178.79, 984.02±196.46 mPa) to the descending aorta (planes 6-8) (1483.06±86.49, 1469.03±81.64 mPa), respectively (p<0.05). This pattern was repeated during exercise (ascending: 1183.17±152, 1073.59±201.97 mPa: descending: 1520.47±230.4, 1551.41±140.54 mPa), whilst cWSS decreased along the arch respectively at rest (ascending: 286.97±105.58, descending: 177.42±69.36 mPa) and during exercise (ascending 462.27±76.64, descending: 316.23±21.09 mPa; p<0.05). Group mean tWSS, cWSS and aWSS across all planes did not differ between rest and exercise at 55% maximal heart rate (P > 0.05). At rest segments on the inner curvature of the arch had a higher tWSS and cWSS and a lower aWSS (1310.90±122.20, 358.45±128.55, 1068.95±250.70 mPa) than the outer curvature (1125.53±190.53, 197.34±65.74, 1232.86±243.57 mPa), respectively (p<0.05). Exercise reversed these shear stress patterns such that tWSS and aWSS were greater on the outer curvature during exercise (outer: 1444.71±212.09, 1350.79±230.91 mPa; inner: 1188.90±167.79, 1105.99±237.24 mPa:p<0.05), whilst cWSS increased along the outer curvature resulting in no significant difference between segments (408.87±86.51, 340.18±98.20 mPa: P > 0.05: Figure 1a-c). Exercise at 55% maximal heart rate increases the WSS in the outer curvature in comparison to the values at rest, whereas there are smaller increases along the inner curvature.