A note in respect of this: the argument that someone will deliberately starve themselves into muscle loss therefore there’s no problem does not strike me as a reasonable working model.

Briefly to explain why: https://www.skysports.com/rugby-union/news/12321/12061901/rfu-world-rugby-facing-questions-over-womens-rugby-transgender-ban

First, it’s inherently flawed. If the argument is that the study is not based on athletes but on average transwomen, if the average transwoman is deliberately reducing muscle before transition, then a larger muscle mass after transition means even less loss in those not reducing.

In other words: if someone reduces their muscle mass before but still has more after, someone not reducing muscle mass before isn’t going to have less than someone starting from a lower base. If anything, they’ll have more yet. That does not suggest smaller mismatches.

It’s also a problem in that there’s no suggestion it affects things like relative neck strength. Holding up a larger skull requires a larger minimum neck strength because it’s simply bigger. How one can diet off that given minimum neck strength for a given skull isn’t explained.

Neck strength is a huge factor in contact and above all in scrums. For example, popping a front row is based on neck strength and is dangerous.

I’d really want to see some explanation of how differing neck strength atrophies when other muscles aren’t. I don’t see that there.

It may well be so, and may show up as so on study, albeit there I didn’t see any data put forward to that effect. It just seems to have an inherent flaw in the logic as presented there. I do fully accept a report isn’t a full paper and it’s not expected to be such.

One thing that does seem odd, though, is that when the original Harper paper specifically noted that explosive or strength-based events might not be affected, surely if this dieting result was an average phenomenon, it should have been noted or showed up on strength there, too?

That paper is here.

It notes one of the cohort studied gained weight after, and became slower; one lost quite a bit of weight, and became faster. There's no mention of dieting to induce muscle-loss beforehand. The second-last paragraph is relevant. https://pdfs.semanticscholar.org/1e6a/bd2c1e03ba88e9ac8da94ea1d69ff3f4878a.pdf?_ga=2.67023150.1834809140.1599151891-306543224.1599151891

It's also not mentioned in the presentation to the Workshop, when discussing muscle or strength loss; you can see all the presentations at the link below.

https://playerwelfare.worldrugby.org/?subsection=84 

As with any decision-maker: if you think something is a vital part of the evidence, then the time to mention it is while you are setting out the evidence before that decision-maker. A decision-maker can't consider evidence not put before them.