Exercise elicits a number of physiologic responses to increase oxygen delivery to working muscles. The beta2-adrenergic receptors (ADRB2) play a role in the cardiopulmonary response to exercise. This review is focused on how the gene that encodes the ADRB2 influences the cardiopulmonary response to exercise. In addition, we discuss possible interactions between ADRB2 and other genes important in exercise performance.