here's a routine is use to isolate my lowr half and try and use as little of my lower back as is possible:

warm-up using stationary bike for 10mins, some light stretching for another 5-10mins,
then over to the leg stations, i like to pre-fatigue my thighs with isolation movements so as to not push so heavy on my compound exercise....

3sets of leg extension, 8-12 reps nice and controlled with a pause at the top...
3 sets of lying hamstring curls, 8-12 reps, nice and slow, toe pointed away from you...
you can superset the isolation exercises for intensity

4 heavy sets of seated leg press, 6-10 reps
then 4 sets of toe-press on the leg press station, 10-20reps nice and controlled pushing up as far as you can go and pausing at the bottom....
then stretch it off after 5 mins on the bike...

should only take about 40mins and is real tuff and safe if done properly...


however this will never substitute my deads/squats/leg press and cleans...
for size/strength