One-Legged Leg Press: Lower Back Pain?

[Psychotron]

I switched from the standard leg press to the one-legged variation. I got up to 8 plates [per side] on the leg press with full ROM [knees to chest] but I experienced a lot of lower back pain throughout the movement. I think it's due to the particular machine that my gym carries. It's a Life Fitness leg press and I think the back pad contributes to this. My form is not the problem, I keep a neutral spine and press my back against the pad while holding the handles throughout the movement. I switched to the one-legged version and prefer it but I'm still having pain in my lower back, only while using my left leg though. That's my question, why is there absolutely no pain with the right leg but significant pain when I switch to the left? Thanks.

 

[Psychotron]

Any Ideas?

 

[fitnessgeek]

Its possible you are off balance enough with just one leg that you are putting an unusual strain on your back. try it with both legs and see what differnce it makes.