Endurance Research Group, Centre for Sports Studies, University of Kent, Chatham Maritime, Kent, UK
Received Date: April 26, 2012; Accepted Date: April 28, 2012; Published Date: April 30, 2012
Citation: Hopker J (2012) The Effects of Training on Cycling Efficiency. J Sports Med Doping Stud 2:e105. doi: 10.4172/2161-0673.1000e105
Copyright: © 2012 Hopker J. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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Gross efficiency, defined as the ratio of work generated to the total metabolic energy cost, has been suggested to be a key determinant of endurance cycling performance [1-3]. Some consideration of the factors that influence cycling efficiency (e.g. muscle fibre type) has been given . However, several fundamental assumptions related to the importance of cycling efficiency have received very little experimental verification. One such factor is whether efficiency can be improved by training. Historically, the majority of evidence investigating the influence of training on cycling efficiency has been largely cross sectional in nature and has failed to establish differences between trained and untrained cyclists [4-8]. However, the majority of these studies can be criticized on the basis of their methods and a failure to address the risk of committing type 2 statistical errors. Additionally, the use of cross-sectional study designs fails to identify whether differences in efficiency between trained and untrained populations are accounted for by inherited genetic factors, or training related effects.
Recently, the use of longitudinal study designs is providing growing evidence for the possibility of increasing cycling efficiency via training [9-12]. Specifically, this research has demonstrated that efficiency can be improved over the course of one , or multiple cycling seasons . In these studies, the increases in cycling efficiency were significantly correlated with the volume and intensity of training completed. Moreover, subsequent research has further suggested that high intensity training might provide the most potent stimulus for improving cycling efficiency . Interestingly, although this high intensity training approach improves cycling efficiency, it does not cause a change in VO2max in trained cyclists. Indeed, an inverse relationship between cycling efficiency and VO2max appears to exist . Cyclists with a high VO2max seem to be less responsive to training related changes in cycling efficiency than those with a lower VO2max .
Even though the studies outlined above have demonstrated that gross efficiency can increase as a result of training, it is still unclear whether such chronic changes will actually impact on performance. Currently, the effect of training-induced increases in efficiency on cycling performance has not been assessed. Additionally, the physiological mechanisms related to training improvements in cycling efficiency and those related to the development of the observed inverse relationship with VO2max , remain to be fully elucidated. Even though not directly related to exercise training, short-term nitrate supplementation has been shown to produce a similar efficiency VO2max response as those described in the training studies above. This contemporary area of research suggests that nitrate affects mitochondrial function, increasing the number of molecules of ATP generated per atom of oxygen consumed (the P/O ratio) and therefore, mitochondrial efficiency . Indeed, high levels of circulating nitrate have been found in high altitude natives, who also display significantly lower VO2 at submaximal work rates (i.e. higher cycling efficiency), lower VO2max values than sea-level inhabitants [15,16]. Thus, it might be speculated that training leads to a natural increase in the body’s nitrate levels, although future research is warranted to test this hypothesis.