Professor José Calbet, global leader in his field, discusses the limitations to VO2 max. Topics include factors determining VO2 max, effects of VO2 max on exercise performance, oxygen delivery as the main limiting factor, differences in VO2 max between males and females, pseudoanemia in endurance athletes, the role of genetics and exercise in VO2 max, blood flow restraint to maintain blood pressure, and VO2 max in masters athletes.