sorry … didn’t realise Mike Nike had responded … I agree with all that Goose has written.
There are no doubt many world class sprinters who did not/could not squat. The best guy I ever coached could not squat, or at least was barred by our chiropractor so I wasn’t about to put my anatomy knowledge up against his. Bottom line, you find alternatives, but hit across a range of options because in truth it is difficult to be certain which kind of training is having the best outcomes - and mixing it up prevents stereotype response, plus picks up on syngerists muscles which may not otherwise be activated doing , say, only squats for leg strength.
Hack squats in a Smith Machine are great in some ways, but you can do simple things such as leg extension and hamstring curl on a machine as an adjunct to hill sprints and you will get good results.
Machines have a bad rap, but the fact they are single plane means they can be used without stirring up some types of injuries. You probably don’t want to lock out the knee though, especially when you’re banging away on the leg extension/hammy curl devices.
My best guy was barred by our chiro from doing anything that may further destablise one of his lumbar joints, so that ruled out cleans, snatches and squats. Apparently it didn’t slow him up, at least for sure not as much as being sidelined by (preventable) injuries.
The hills though really work the hips which the leg extension - hammy curl machines don’t touch. By the way, the machines we used were the Keiser pneumatic machines (they also have a leg-press machine which I didn’t think much of). We added in some pulley work, as well as we did some sets on the Keiser hip-flexor machine which I think was useful.
A lot of physiotherapists have keiser in their clinics and some of the physios - the half decent ones - won’t mind if you do a bit of training on them, (probably so long as you buy them a nice bottle of wine from time to time; or bring your superstar athlete friend down to be seen to be seen, signing the odd fan photo)
By the way Iwan Thomas didn’t win a world (outdoor) 400 title, although on his day he was certainly good enough during the period he was at his best. He was dominant at the 94 Comm Games (which he won in around 44.57?) and had that been a world championships, he may well have won it (although on reflection, Michael Johnson was in his prime by then, so…).
By the way I had the great pleasure of being introduced to Iwan in the Athens transit lounge by former UK coach/admininstrator and fellow Welshman, Tudor Bidder. Iwan seemed to be a top-shelf man, from the brief chat time permitted us.
Goose, did you work with Iwan? How is he doing these days? I heard he had gone through some tough times, sadly like too many of our great former champions.