I think this is very interesting, anecdotally I know a lot of grippers (Heavy lifters) who seem to have lost hair, but that might not just be a testosterone thing, I also know a lot of strict veggies who have got pretty thin hair- when as they eat no meat- they should have a diet which reduces testosterone levels. In both cases the body may be stressed to some extent an may be conserving amino acids for vital functions thus thinning the hair?
Also heavy lifting does put a strain on the blood- in terms of pressure (I have seen power lifters get nose bleeds etc) and blood glycogen levels ( have fainted after heavy squats- tend to prefer football & cardio now

)
I would be fascinated to hear about the results of any proper research in this area- not that I intend to resume my squatting carrier!
very best
NV