Fday said:
As I am sure you know, the question is not whether one needs a PM for training but whether using a PM is demonstrably better than other available training methods.
again FDay... power meter don't define a method of training... they are a tool to measure intensity of training... that's it! what they offer is the most accurate measure of intensity/power... because they actually.... MEASURE POWER... directly
no one needs a study to determine this... it's obvious... power meters are the most accurate measure of training intensity/power..
e.g. i just did a sprint workout yesterday.. this probably worst case scenario... 5x 10-15 sec sprints... 2 uphill from standing and 3x flying start down a slight incline..
RPE... well, they all kinda felt hard... RPE is pretty useless.. although with MANY years of practice you may be able to get good at determining intensity with RPE
speed/stopwatch not bad if you keep everything constant but... that's pretty hard a lot of the time... the speed of the downhill ones where WAY faster than the uphill ones + tailwind in one direction and cross wind in the other...
HR... didn't really budge over those 10-15 sec... so, pretty much useless... well, completely useless actually
the other "training methods" you mention are not even training methods either... they are method of measuring intensity of training as well and they ARE certainly demonstrably inferior methods of measuring intensity... this is obvious to anyone who has used a power meter... HR can be all over the map on given days or not even budge or change enough to determine what power you are riding at/intensity... pretty much useless for most interval training. Speed inside can actually be VERY accurate at determining power, but outside is very inaccurate at predicting power/intensity (hills, wind etc)... RPE is not as accurate as a power meter at determining power but one can actually get some degree of accuracy after many, many years (hard because of changes in motivation and freshness day to day... wind, false flats, road condition etc, etc.).
again... your question doesn't make sense... using power to train is not a training methodolgy