Your body adapts to the footwear you grow up in. If you grow up wearing shoes with lifted heels, your tendons will shorten to compensate. The average running shoe these days has a heel lift of about 10mm (6mm lower than when I was in college). Of you wear shoes like this all the time you’ll experience Achilles tendon pain if you try to transition into a show with a heel to toe drop of 6mm or less too quickly.

You’ll see barefoot running advocates saying you can run injury free with 0mm of drop, or at the very least without more injuries than a shod runner, but people frequently misinterpret that to mean “you should start going barefoot immediately” which isn’t what any barefoot coach would recommend. In fact for most athletes what makes the most sense is a mix of shod and unshod running. Super ironically, to bring it back to Nike, they DO have a couple of really important innovations in running technology. One of those was that Oregon’s long distance coach, and Nike’s founder, created a custom pair of shoes for one of his athletes who was experiencing Achilles tendon pain on her long runs. The innovation was to take a mostly flat running shoe (as was the style at the time) and introduce a 4mm foam wedge to relieve that tendon pain so she could still get in her long miles.

Note! Even then, at the beginning of Nike, the advice to the high level athlete was “mostly run this way, but sometimes put on these other shoes.” That’s still what most serious coaches and athletes are doing. You do most of your running with a pair of shoes with some lift or barefoot, and then you do a minority of your mileage in a shoe that’s more or less minimal than your daily trainer. The real fallacy of running footwear is the notion that any one single thing is your solution to everything.