Oldest-old adults are expected to represent 4.8% of the world population in 2030 (400 million). Aging influences functional capacity (FC), which is relevant information for this subpopulation and can be assessed by maximal oxygen uptake (VO2max) with a conventional exercise test (ET). Exercise-based programs for advanced older adults could improve health status and multiple studies support resistance training as an important option. An observational, retrospective study on FC assessment, with VO2max assessment, in the oldest-old adults, is presented. Eighty-six individuals, ≥75 years old, were included. FC was estimated by VO2max obtained with treadmill ET. Two groups with different FC were compared (A group: <24 mg/kg/min and B group: ≥24 mg/kg/min). Most important differences were found in body mass index and heart rate, with a correlation between these variables and both with VO2max. These findings can help the oldest-old adults’ health care, once exercise programs provide multiple benefits for this subpopulation improving these specific variables, and other clinical aspects. Pre-participation assessment could promote safety, comfort, adherence, and effectiveness in advanced older adults. Exercise programs, including resistance training, impact quality of life, cognitive status, frailty symptoms, risk factors, and all-cause mortality.