tag:blogger.com,1999:blog-8803144976327688451.post4807484745578643356..comments2024-03-15T01:19:36.314-04:00Comments on Research Trailer Park: Phun Physiology: Endurance Exercise Performance — Speed or PowerMike Daytonhttp://www.blogger.com/profile/06558296158677358300noreply@blogger.comBlogger2125tag:blogger.com,1999:blog-8803144976327688451.post-63175283478674634272009-11-28T19:04:41.439-05:002009-11-28T19:04:41.439-05:00Hi, Maria,
Thanks for the cycling physics referen...Hi, Maria,<br /><br />Thanks for the cycling physics reference regarding power which I’ve often wondered about and which I think RTP readers will appreciate!<br /><br />What you heard is correct on all counts about muscle fiber (cell) types.<br /><br />Allow me to summarize for the benefit of readers. There are two broad categories of muscle fibers—type I and type II, referred to as “slow” and “fast” twitch, respectively.<br /> <br />Endurance sports depend largely on type I muscle fibers.<br /> <br />http://www.ncbi.nlm.nih.gov/pubmed/1501563?dopt=Abstract<br /><br />Additionally, Type II muscle fibers comprise three subtypes: IIa, IIx, and IIb.<br /><br />Interestingly, in spite of the fact that the types, subtypes, and percentages of muscle fibers are genetically determined, “adult skeletal muscle shows plasticity and can undergo conversion between different fiber types in response to exercise training or modulation of motoneuron activity.” (from the following source with hotlink references):<br /><br />http://www.plosbiology.org/article/info:doi%2F10.1371%2Fjournal.pbio.0020294<br /><br />Specifically, type IIb fibers can be converted to both type IIa and type I fibers. This is fortuitous on both counts for endurance athletes, since type IIa fibers are preferred to type IIb given that the former are less prone to fatigue, while type I fibers are least prone to fatigue and are the most preferable and the type which are factored into the efficiency factor of the model featured in the bog entry.<br /> <br />For those who would like to learn some basics about muscle fiber types, the following reference is an excellent primer with the exception on the topic of whether muscle fiber types can be interconverted.<br /> <br />http://www.coachr.org/fiber.htm<br /><br />Thanks!dean furbishhttps://www.blogger.com/profile/12555785432014282728noreply@blogger.comtag:blogger.com,1999:blog-8803144976327688451.post-16782309948001102372009-11-28T16:01:59.787-05:002009-11-28T16:01:59.787-05:00Hi Dean,
What a great resource! As you know from ...Hi Dean,<br /><br />What a great resource! As you know from some of our conversations, I'm very interested in all these things. <br /><br />I didn't see this mentioned in any of the refs to the article from JoPhys., but one of the trainers at my gym says that even though we are born with certain percentages of fast and slow twitch muscle fiber (type I vs. type II), there is a third kind that, through training, can be recruited to be either slow or fast twitch.<br /><br />Do you know anyting about that?<br /><br />Thanks for the info!<br /><br />PS. Watching the TdeF this summer I became interested in the details of reported power output for the elites...simple physics just doesn't work. I found this article interesting too.<br /><br />http://www.saris.com/t-powerBasics.aspx<br /><br />MariaAnonymousnoreply@blogger.com