Quotes from What I'm Reading: Lore of Running on the Heart and Oxygen Transport
"I now believe that the heart's pumping capacity, determined in part, by the maximum coronary blood flow, may indeed limit maximal aerobic exercise performance in events lasting a few minutes. This capacity is determinated by the heart's maximal pumping capacity at the point at which the maximal blood flow to the heart is about to be reached. This must be a regulated process, however, as the actual maximal blood flow to the heart must never be achieved (or else chest pain and heart damage would result). Rather, as Hill and his colleagues proposed, there must be a governor that terminates exercise before the heart and exercising skeletal muscles are forced to contract anaerobically. It seems probable that the heart's maximum ability to pump blood does determine the VO2max, but not by the mechanisms popularly presumed. Exercise must terminate before the heart itself becomes anaerobic, or ischemie, as it is the heart, not the skeletal muscles, that is at greatest risk of developing anaerobiosis during maximal exercise. This concept was well recognized by the early researchers, including A.V. Hill and David Dill (Noakes 2000c) To prevent the heart from becoming anaerobic during exercise, there would indeed be a need for a governor that anticipated when the blood and oxygen supply to the heart was about to become inadequate. Physiologists do not like the idea of subconscious physiological processes that function by anticipation (that is, by predicting the future). Prediction of the future is, they believe, reserved exclusively for the conscious processes in the higher brain centers. Yet, evidence that this governor has anticipatory capacity is shown by human responses to a reduced oxygen supply in the inspired air, as occurs at altitude. This governor, presumably located in the brain, would, In response to Information from the heart, and perhaps even the coronary blood vessels, reduce the recruitment of the muscles already active. Alternatively, the governor might prevent the recruitment of additional muscle fibers necessary to further increase the work output and oxygen consumption. Were this to occur, additional demands would be placed on the heart, increasing its oxygen demands and thereby precipitating myocardial
Ischemia, or anaerobiosis.
Hence, the the postulated governor would cause exercise to terminate before there was a plateau in whole body oxygen consumption or, more Important, In the heart's blood supply and oxygen consumption. In this way, neither the heart nor the skeletal muscles would develop anaeroblosis during maximal exercise, and exercise would terminate as a result of a plateau in the recruitment of any additional fibers In the exercising muscles by the brain."
About Lore of Running, 4th Edition, by Tim Noakes: Noakes is a leading researcher in the field of exercise science, perhaps most famous for his theorem of a "central governor" in each of our brains that limits us from reaching our true, maximum athletic output to protect us from going too far and hurting ourselves. Lore of Running has been touted as a must read by any serious runner or coach, and I came across it at the AirBnB that Hannah and I are staying at for 5 weeks in Boulder, Colorado.