I know that Mike Stevens has commented in public on this in the past.
He also injured himself in triathlon (I think) events.
As good as a harp player as he is, I really don't know why he injures
himself. He has also stated that overblowing is hard on his lips.
Again, I can't imagine how. Mike seems predisposed to twist himself
in knots physically to get results. He comes across as an amiable,
nice guy of mellow disposition and easy self-assurance, not some
hopped-up maniac hell-bent on self destruction, so it's kind of
mystifying.
Looking at players who are in some way comparable, like Howard Levy,
Joe Filisko, Carlos del Junco, Wailin' Wood, Charlie McCoy, I'm not
aware of any physical injuries or problems they have incurred as a
result of playing the harmonica in similar styles or on the edge of
what is considered physically possible.
As is so often the case, one suspects that it is the player and not
the instrument.
Winslow