At the top of his career, Miguel Indurain had a physiology that was not only superior when compared to average people, but also when compared to his fellow athletes. His blood circulation had the ability to circulate 7 litres of oxygen around his body per minute,
[1] compared to the average amount of 3-4 litres for an ordinary person and the 5-6 litres for his fellow riders. His cardiac output is 50 litres a minute; a fit amateur cyclist's is about 25 litres a minute. Also, Indurain's lung capacity was 8 litres, compared to an average of 6 litres. In addition, Indurain's resting pulse was as low as 29 BPM, compared to an average human's 60-72 bpm, which meant his heart would be less strained in the tough mountain stages.
[2] His VO2 max was 88 ml/kg/min; in comparison, Lance Armstrong's was 83.8 ml/kg/min and Greg LeMond's was over 92 ml/kg/min.
[3]