Runners with high arches have been directed toward soft, well-cushioned shoes, since it’s thought that high arches prevent adequate pronation
I have very high arches and over-pronate. So much for that theory.
I find I need far more arch support than any shoe provides, so get (cheap & basic) orthotics, and sometimes add a wedge of rubber to give a little extra arch support. Otherwise the Achilles get really sore and swollen, as well as the knees giving me trouble.
On the other hand, how much of the stiffness and soreness the testees were reporting results purely from them adjusting to a different shoe, and thus working muscles slightly differently?