Interval aerobic training programs (IATP) improve cardiorespiratory and endurance parameters. They are, however, unsuitable to seniors as frequently associated with occurrence of exhaustion and muscle pain. The purpose of this study was to measure the benefits of an IATP designed with recovery bouts (IATP-R) in terms of cardiorespiratory and endurance parameters and its acceptability among seniors (≥70 years). Sedentary healthy volunteers were randomly assigned either to IATP-R or sedentary lifestyle. All participants performed an incremental cycle exercise and 6-minute walk test (6-MWT) at baseline and 9.5 weeks later. The first ventilatory threshold (VT1 ); maximal tolerated power (MTP); peak of oxygen uptake (VO2peak ); maximal heart rate (HRmax ); and distance walked at 6-MWT were thus measured. IATP-R consisted of 19 sessions of 30-minute (6 × 4-min at VT1  + 1-minute at 40% of VT1 ) cycling exercise over 9.5 weeks. With an adherence rate of 94.7% without any significant adverse events, 9.5 weeks of IATP-R, compared to controls, enhanced endurance (VT1 : +18.3 vs -4.6%; HR at baseline VT1 : -5.9 vs +0.2%) and cardiorespiratory parameters (VO2peak : +14.1 vs -2.7%; HRmax : +1.6 vs -1.7%; MTP: +19.2 vs -2.3%). The walk distance at the 6-MWT was also significantly lengthened (+11.6 vs. -3.1%). While these findings resulted from an interim analysis planned when 30 volunteers were enrolled in both groups, IATP-R appeared as effective, safe, and applicable among sedentary healthy seniors. These characteristics are decisive for exercise training prescription and adherence.