What Muscle Fibers are Used at Different Cycling Cadences?

Question

Diễn đạt lại các khía cạnh chưa hoàn thiện của vấn đề đã nhân trung ấp – kiến tập.

Answer 1

When spinning at higher cadences, particularly 90 RPM and above, only the type II fast-twitch muscle fibers which can generate short bursts of energy but are quickly fatigued are recruited. However, as the cadence is lowered to about 80 RPM, more of the slow-twitch muscle fibers which are less powerful and more efficient during low-intensity activities are recruited. This change can reduce energy expenditure during a workout and lower muscle fatigue – factors which are crucial when one seeks improvement in cycling efficiency.

Comments

Each person has a different combination of fast twitch to slow twitch muscles, I imagine that the ideal cadence will be different for everyone based on that

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.Slow twitch muscles are the aerobic fibers.  They deliver oxygen to the muscles directly and expel lactic acid.  Fast twitch muscles use glycogen , a finite resource, that to recover rider has to slow down.  As you found out, climbing with a lower heartrate, rapid cadences train the slow twitch aerobic fibers.  The legs can't jam down on the pedals.  They don't have enough time.  They must follow the crank around.  The heart and cardio system get a splendid workout, increasing VO2 max, speed, strength, and endirance.  The legs expel lactic acid and can go forever.  Following the crank around in slow cadences is also more efficient aerobically.  Doing spin intervals does the trick.

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Not really true. Muscles can be trained and pro cyclists are extensively trained to ride for long hours at high cadence because cardiovascular system recoveres faster and tires slower than leg muscles. Just look at them go at races - most of them are riding at 100+ rpm on flats. And every pro or coach out there immediately spots a rookie by their slow cadence.

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Leonard, I think you made some good points here, and maybe the composition of fast and slow twitch fibres influences what is best for each induvidual. Myself I upgraded my bike from 11 to 22 gears, giving me more range and allowing spinning up 8% climbs at 150 heartbeats/ minute in stead of 160. But I lost speed. Grinding up the hill was faster, and also exhausting.  Myself I guess I am fastest and most efficient when I feel the right torque under my legs. That torque feels natural for me at maybe 70-85 rpm (rpm is guesswork,  I dont have a meter, but some experience from a indoortrainer with a meter), when it spins faster I am faster when clicking down to a heavier gear.  I often spin into the hill at maybe 85-90 rpm, and the rpm goes down as the hill gets steeper, and soon cadence slows down and it gets too heavy, and I have to choose a lighter gear.   I think I am faster at 80 rpm than I am at 90. Roglic is different and strong at high rpm, maybe he is full of fast twitch fibres? I think its smart to train on different cadences.  If I go too heavy I think my legs faster gets muscletired.

I am fastest when I go as heavy as I can before it feels  heavy. When it feels heavy I choose a lighter gear. Maybe I am even faster when its too heavy, but that torque I cant keep long.

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Honestly just viewing your size I would suspect a lower cadence to be better. higher cadence tends to be better if you have a strong cardiovascular system, which is much easier to have if you are lean or heavily trained. Slower cadences are fine short term but as others said your muscles tire, so I vary my position to keep that going. Once you cramp it's kinda game over for high speed efforts. I naturally have a slower cadence and weight lift and so I can produce decent power at slow cadences, but it takes a toll on my muscles and joints. So next stop for me is high cadence. Of course crank length to leg length ratio matters too. I have a 34.5in inseam and with 165mm cranks I spin quite a bit more then on my regular 170's or 175's.

The muscle type is malleable. A great example is the current world strongest man mitchell hooper. He was a marathon runner a couple years ago and now he is not. So he "went" from slow twitch to fast twitch.

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Age and physiology make a huge difference. I'm not sure you're right with fast/slow twitch muscles vs fast/slow cadence. Personally my own physiology tends towards greater slow twitch muscles,  I can run long distances easily and same for cycling, but I couldn't generate enough power to pull the skin off a rice pudding.  Ended up fitting a 46/30 grx chainset and front mech to my bike as I can't push 50/11 let alone 53/11. Spin 90/100rpm all day as each revolution requires less power.
You are right in that do what works for you.  At 63 I'm happy  to be out on my bike at all. Keep em coming Leonard

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Leg weight is a consideration here. Lifting a heavy leg (no offence intended to the heavy-legged riders) obviously takes more energy than rotating and lifting a leg 5kg lighter. This energy expenditure adds to the overall workload of the rider. So heavier riders could indeed benefit from reducing the number of leg lifts they do each minute in that less of their energy will be used moving their legs upwards against gravity - be that from pulling up or pushing down. For more svelte riders the power used in moving their legs around will be less of a percentage of the overall workload so they may well be in their 'sweetspot' at higher cadences. So dropping cadence might only benefit heavier riders.

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Hey, you got the slow/fast twitch sprinter /endurance rider around the wrong way at the end of the content.

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I listened to all the guff about high cadence pedalling and totally ignored it. Cadence self selection by your own brain, is the way to go. Cadence is related to your strengths and weaknesses biologically. Everybody is different, some put out high torque like me, some put out low torque but can push the pedals around faster to compensate for this but the best cadence is the one your brain chooses for your body. It knows best !
I won open, inter club time trial races with a cadence generally  around 60. At the same time at my aerobic heart threshold of 170 beats per minute, which has been the same for decades through constant training. Your assumption that a higher cadence directly equates to a higher oxygen rate is wrong. The figure that dictates this is the power after gearing at the tyre. Cycles have gears and whatever cadence you maintain is trumped by the gear you select,  so you can have a high cadence and a lower gear cyclist and also a low cadence and a higher gear cyclist putting out the same total watts at the tyre and the only place that power comes from is the rider, who if the total powers at the tyre are the same then the rider work done is the same. The other thing you said that I think was wrong, is that you said sprinters probably prefer lower cadences and vice versa for endurance riders. I can't sprint for toffee and thus have a much higher concentration of low twitch fibres making me a much more endurance based rider and runner, yet I ride at an average cadence of 60 rpm, totally the opposite of what you suggested.

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I don't have one cadence that feels natural. The easier I'm taking it, the slower my cadence. If I'm doing an all-out effort, my cadence is high (eg. 100-110). An exception is climbing where I've run out of gears forcing a slower cadence for the watts. Strangely, it can feel fine climbing at a lower cadence/high torque/high watts, but I don't like pedaling on the flats that way and I can often generate a higher average watts up a hill under those slow cadence conditions without feeling as gassed. Maybe it's that under high inertia conditions (flats) a higher cadence works better, and the reverse is true under low inertia conditions (hills).

btw, the whole fast twitch/slow twitch naming is confusing and not very intuitive. I believe you're actually using your 'fast twitch' fibers more with higher torque pedaling at lower cadences. For instance, a power lifter isn't moving the weight very fast, but they're using fast twitch. something like "low cadence cycling uses fast or slow twitch muscles" rather than relying on what the fiber names intuit or on generic articles that lump cycling in as endurance and therefore slow twitch.

Great content, in any case. :)