T Nation

machine leg extensions

When doing machine leg extensions how
many degrees are you supposed to do on the descending part of the exercise? My machine will let you go past vertical(90 degrees)
on the way down and I think that may be leading
to knee pain.

Going beyond 90* knee flexion is not a likely cause of knee pain. I feel from a BBing perspective the more flexion the better. A much more likely cause of pain with leg extensions is too much weight! Try using a 15-20 rep scheme with a 2-0-2 tempo, full ROM and constant tension using a light load.