Another question to consider is what are the implications of excessive METCON in terms of muscle hypertrophy?
Typically when you see professional bike racers with big legs they are either track riders or in the case of the TDF (and similar) they are sprint or flat stage specialists, and not GC contenders. Guys that are GC contenders need to be good climbers. Typically I guess what one might call 'wiry'. With any events of this nature at the end of the day you need to be able to 'carry your own engine'...Well, certainly in that context (TDF riders), you would expect some suppression of hypertrophy even though you see some riders with what appears to be big legs (cause or effect?). I suspect that METCON is not helpful. When I see skinny guys doing burpees and air squats, I wonder what they are trying to accomplish.
Also take into a account the massive use of PEDs in the world of professional sport, especially cycling...I've tried to find info on body comp/weight changes of riders in the Tour de France or other long duration events and not having much luck. For as long as it lasts and at that intensity I'd expect any muscle mass catabolism to rear its head before the end. This is probably confidential team data.
Endurance.When I see skinny guys doing burpees and air squats, I wonder what they are trying to accomplish.
Also take into a account the massive use of PEDs in the world of professional sport, especially cycling...
I'm sure they take stuff to prevent or reduce lean mass catabolism.
A study like that wouldn't yield results that you can apply to the general population IMO.
Endurance.
I knew a lot of them back when I did crossfit. Couchpotatos and even weekend warriors will experience big improvements in endurance from doing metcons.
You probably need to understand that they define "endurance" different compared to you. They never test something like a half-marathon or similar. They define "more endurance" as the small things like not sucking wind anymore while carrying their groceries back home or going up 4-5 flights of stairs.
Metcons will do that for you.
It's hard to tell someone with a busy job, family etc. that for long term results it's probably better to follow a plan of hour(s) long slow locomotion work a couple times per week, when they experience big improvements in endurance (-> how they define the word) with 2-3 5-10min metcons per week and afterwards feeling "accomplishment", because they "crushed the workout".
I did both kinds of sessions in my life and I honestly have to say lying on the ground in a pile of my sweat and slowly regaining a normal breath pattern feels better/more satisfying than coming home from a 90min LSD run staying below your MAF HR.
Yes of course, but that would mean taking the time and effort to first educate yourself how to do that and then putting in the time and effort to work on those things and most people simply don't want that.If they truly want to improve across the spectrum of Crossfit WODs, they would be better off minimizing the METCON and maximizing the basic strength work.
Maybe off topic a bit but Spartan racers incur a 30burpee penalty for every missed obstacle. I actually know some who purposely train burpees to be prepared for this. ( sadly, I tried that too... )
Better is to train the elements of the obstacles to minimize or avoid burpees altogether...