>>76797367
Completely different exercises. a) leverage is much less during the knee extension b) Sir Snapsalot here probably ruptured his ACL, which is not possible on a knee extension machine
In regards to the ACL problem, bear in mind that your ACL rupture when your shin dislocates forward, which is basically what this weird reverse-nordic-curl does; you can clearly imagine how that metal bar is pressing into the back of his calf and really wants to push his shin anteriorly. Leg extension machines are the opposite, the bar is pushing you shin backward/posteriorly.
Most knee extension machines are also designed such that equivalent resistance is much lower when your knees are bent, whereas the reverse nordic is the opposite.
Both exercises are ego lifts in their own right.
>t. physiotherapy fag