Originally Posted by Flexor
I think the technique has been pretty well covered here.
In terms of strength relationships between the hip extensors and knee flexors, I'll say this. The preferred strength ratio for static exercises between the quads and hams is 3:2, 1:1 for explosive concentrics and 2:1 for for slower contractions. A lot of people neglect their hamstrings with both direct curling movements, hip extension exercises and plyometric or explosive exercises, whilst they are hitting their quads hard with squats and lunges. This leads to a strength imbalance between the two opposing muscle groups and may effect how can you can perform certain movements such as deadlifts. Unfortunately I have no data on glute vs. knee extensor strengths, but this would be a very similar factor. The glutes together with the hams would be far stronger than the quads, so there is the issue. You need to balance quad vs. ham and glute strength. Squats would probably be the answer