We present an open-label, multicenter, prospective, controlled and randomized study in order to evaluate the usefulness of preoperative isometric exercise (PIE) in pre-dialysis patients or in prevalent HD with indication of performing a new AVF. The randomization will be 1: 1, one group of patients will perform PIE for 8 weeks and the other group of patients will be a control group. The main purpose will be to evaluate if there is a lower rate of primary failure in the PIE group compared with control group.