Sickle Cell Pro-Inflammatory Response to Interval Training Study

The investigator's plan to evaluate the effect of acute exercise and exercise intensity on circulating systemic pro-inflammatory mediators and airway bronchoconstriction in SCA. The investigators hypothesize that regular exercise at moderate to vigorous intensity is safe for children with SCA and do not precipitate SCA-related symptoms. In this multicenter study, 70 non-asthmatic children with SCA and 70 controls without SCA will first undergo a maximal cardiopulmonary exercise test (CPET), then be randomized to an exercise challenge by controlled intensity interval training (CIIT) at either moderate or vigorous intensity (8 exercise bouts at 50% or 70% peak workload, respectively). The Investigator's Aims are to: 1) Determine the influence of exercise intensity on the acute inflammatory response to exercise, defined by an increase in soluble vascular cell adhesion molecule (VCAM) and other adhesion molecules, and 2) Define the effect of moderate to vigorous exercise on forced expiratory volume in 1 second (FEV1) and acute bronchoconstriction in children with SCA. The investigators will also explore exercise- induced changes in gene and microRNA expression in peripheral blood mononuclear cells, tissue oxygenation during exercise by near infrared spectroscopy as well as the role of hyperventilation in bronchoconstriction using eucapnic voluntary hyperventilation testing in a subset of participants.