The purpose of this case study was to determine whether a patient with Friedreich ataxia (FA) would experience a clinically significant physiologic adaptation to aerobic endurance training. A 38-year-old man with FA underwent graded exercise testing with collection of expired gases on a bicycle ergometer before and after training, to determine maximum work capacity and oxygen consumption. Training consisted of 27 electrocardiographically monitored exercise sessions on the ergometer, each for 20 to 25 minutes at a workload adjusted to achieve an exercising heart rate equal to 70% to 85% of his pretest maximum, preceded and followed by a stretching routine. Large increases in cardiorespiratory and work measures demonstrated clinically important physiologic adaptations to aerobic conditioning in this patient. Peak VO2 increased 27% and peak ventilation increased 21%. Total exercise time increased five minutes, reflecting a 50-watt increase in maximum workload. In addition, the patient experienced a 4.75-kg weight loss. A medically supervised endurance training program can increase aerobic work capacity and promote weight loss in patients with FA who can pedal a bicycle at training level intensities.