In the present proposal the investigators wish to assess the effect of a single session with the device known as Exer-Rest® which applies Whole Body Periodic Acceleration (WBPA) on baseline airway blood flow (Qaw) and in Qaw variation, in current smokers, glucocorticoid-naïve asthmatics, and age-matched healthy never-smokers, with the expectation that the treatment will transiently increase the Qaw, and to a greater extent in the current smokers and patients with asthma who have endothelial dysfunction.