My partner and best friend came from the lineage that created World Tour pros and TDF winners and low cadence work is one of their staple workouts.
Really, I think almost all coaches agree with doing various types of training and this falls far into the various category, if you look at torque quadrant analysis you are more in that top left quadrant on this page which is something many people don’t get.
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I believe it makes knees stronger if you do it right but you should start with shorter intervals and move to longer. Really in the 55 range Andrea would suggest doing Z5… which is way more stressful. We have both Z2 and Z5 low RPM workouts in Coach Jack. So you could also go to higher torque from where you are but easing into it is a good idea.