Is there any specific training to improve cycling mechanical efficiency?
By cycling mechanical efficiency I mean the % of fuel burned in the body that gets converted into mechanical energy at the pedals. I’ve heard this can vary from 18-25%, which is a huge range. And a seemingly small improvement would have a sizable impact on FTP. For example, going from 20% to 21% would increase FTP by 5%.
I understand about minimizing unnecessary body motion on the bike, and I try focus on that on all of my training rides.
My interest lies more in improving the underlying efficiency with which muscles transform fuel to mechanical work. I find that I get and stay hot very easily when training, leading me to believe my efficiency is low - as most “wasted” energy is expended in the form of heat.
Anyone have experience trying to move the needle on cycling efficiency through training? Or maybe this just happens “naturally” as part of any cycling plan?
Just resurrecting this as I have the same “problem”. I few years ago I had a Metabolic Efficiency test and my Efficiency came out at 17/18% rising to 19/20% around my threshold. I too get very hot very quickly when cycling and really don’t like hot weather for cycling in.
Thanks for digging this up. It’s a hot topic as you can tell based on the number of replies to my original post.
Since that time, I’ve come across a few studies that indicate type I fibers are more efficient than type II.
So I’ve concluded that the ways to improve efficiency are the same as those that train type I fibers (lots of endurance riding) and “convert*” type II to behave more like type I (high tempo/sweet spot). Which is the same training as I’m doing anyway.
In this study, the slow twitch group had ~10% better mechanical efficiency than the fast twitch group (22% vs 20%).
Edit: *adding a side note:
By the way, I’m not clear on what’s actually happening when I’ve heard people refer to “conversion” of type II to type I.
Do fast twitch actually convert to slow twitch? (I recognize there are fast twitch IIa and IIx, and hybrid muscle fiber types also, but in the interest of keeping the discussion simple, I’m just referencing the two types).
Or do fast twitch stay as-is, and what improves is 1. Your ability to transport lactate from fast to slow twitch fibers and 2. The ability of slow twitch to process that lactate.
Thanks. My understanding is that there are basically 2 types of typeII fibres. One that remains as purely fast twitch powered by glucose and one type which for the sake of argument is a hybrid which if untrained behaves mainly as a fast twitch but also is powered by fat oxidation. It’s that part of it that long endurance rides train to behave more like a type 1. I’m quite prepared however to be contradicted.
Summarizing the Friel blog post, based on his review of pubmed/etc the following are possible ways of improved economy:
being born with a long femur bone relative to total leg length
being born with a high % of slow twitch muscle fibers
increasing the number of mitochondria
more efficient pedaling technique
reducing excess weight (body and bike)
more aero equipment
training at higher intensities (speed work) and higher frequency
The blog post also stated that sports science has the least understanding of economy, as compared to the other two primary determinants of performance (aerobic capacity, lactate threshold, and economy).
Ultimately, fiber types are defined by the myosin isozyme they express. Endurance training causes your type IIx fibers to begin to express type IIa myosin, and your type IIa fibers to express type I myosin. At some point, you’d say that the fiber had been “converted”, but hybrid fibers co-expressing two, or even all three, of the major isozymes can exist at any time.
Converting IIx fibers to IIa fibers is easy; converting IIa fibers to I fibers is difficult (to the point that controversy still exists in some circles).
Going the other way, sprint training may (or may not) increase type IIa myosin at the expense of type I myosin, but like endurance training it causes rapid conversion of IIx fibers into IIa. The only way to have lots and lots of IIx fibers is to become paralyzed (not recommended).
Last comment: there are multiple determinants of the contractile properties of muscle beyond just the type of myosin that is expressed. The latter is, however, what science ultimately hangs its hat on when defining a fiber’s “type”.
That almost certainly has much more to do with your degree of acclimatization, body composition, etc., that it does with your mechanical efficiency. At most, the latter only varies a few % between individuals, which means that even an inefficient cyclist only has to dissipate a few % more joules of heat energy compared to a highly efficient one.