Sports today are closely linked with sport science; a research field with roots in many early Nobel Prize winners` work in physiology or biochemistry with Hill being a key pioneer. The primary goal at the time was to understand basic functions of the human body during exercise, and not the least providing answers to which organs or functions of the body that set a limit for human performance. Three examples will be presented, hopefully demonstrating that it is worthwhile and challenging to study the basic mechanisms for human performance and that the inclusion of elite athletes in this research adds crucial insights. Human skeletal muscle plasticity. The potential for a marked elevation in mitochondrial capacity is similar in type 1 and 2 fibres of human skeletal muscle. Usage of the two major motor units during the training is the critical factor. The triceps brachii muscle having the highest relative percentage of type 2 fibres may reach as high a mitochondrial capacity as a muscle with a dominance of type 1 fibres, as demonstrated in world class cc skiers. Thus, there is a clear dissociation between phenotype expressions of the contractile proteins as compared with the proteins regulating energy metabolism. Humans may be quite different from other species where there is a closer link between contractile and metabolic characteristics of the specific fibre types. Muscle glycogen and fatigue. The link between the need for a large intake of carbohydrates to maintain large stores of glycogen in the human body for good endurance performance has a long history. Only recently have these studies reached the subcellular level. Glycogen granula are stored at different locations in a muscle fibre with two main sites around the mitochondria and close to the transverse tubuli (TT) and the sarcoplasmic reticulum (SR). Both stores are crucial, but the one close to the TT and SR systems appears to be essential not only to secure proper propagation of the action potential but also for the maintenance of the SR kinetics. With too low amounts of glycogen, the reuptake of Ca2+ from the cytosol by the SR system is retarded and peak tension development reduced; a mechanistic link, which is the same in both the main fibre types. It is worth highlighting that experimental evidence for the intake of ample amounts of CHO playing a role for endurance has been available since the late 1800. However, it has taken more than a century to explain why glycogen plays this crucial role. Was Hill right or wrong? In 1923 Hill and Lupton wrote: "The volume of oxygen actually used by the heart is almost equal to that required (but not obtained) by voluntary muscle during very violent exercise. The muscle has to stop, owing to oxygen want". A view heavily debated through the years up to our time without reaching a consensus. Our data demonstrate that Hill was right. When elite cc skiers work either with their legs (roller skies on a treadmill), with their upper bodies (double pooling), or by using the ordinary diagonal style (whole body exercise) it was demonstrated that in the latter exercise muscle blood flow and O2-delivery were markedly reduced from peak levels, giving support to the notion once proposed by Hill that the heart was unable to deliver the blood flow that the muscles were asking for. What is the value of the above given findings? Primarily they serve as tools in the understanding of regulations and limitations of basic human functions. They may also be of some interest to the "curious" athlete or coach, but they are hardly of any "help" in the athlete`s preparations to reach Olympic level performance.
© Copyright 2012 The biomedical basis of elite performance. 19-21 March 2012, London, UK. Abstracts & Manuscripts. Veröffentlicht von The Physiological Society. Alle Rechte vorbehalten. / Übersetzt mit https://www.DeepL.com/Translator