The initial power calculation to randomize 10 patients to each arm (20 total) calculated to have 80% power to demonstrate a significant reduction of GRK2 expression with HIIT in this population was based on a prospective exercise training study in patients with chronic heart failure.13 Moreover, data of one patient in the HIIT group were not available for GRK2 expression. This evidence concerns the gene GRK2 and congestive heart failure.