I've changed to a lower/upper split workout. The lower consists of lunges, standing calf raises, lying leg curls, squats, and biceps curls (the curls are just because I have five routines for the upper workout and needed to round out the lower with five).

When I do the lying leg curls, I experience a little pain in my lower back, left side. As a matter of fact, every time in the last five years I've worked with weights, I have a nagging pain there most of the time.

Anyway, I want to see if it's the lying leg curls causing the pain, so I wanted to substitute something else for that exercise. Or do I need to? Do the dumbbell squats I currently do work the muscles that are worked during lying leg curls? If yes, then is there another exercise I can do that works some other muscles in the legs not worked by the squats, lunges, and standing calf raises?

Thanks!

Deadlifts will work your hamstrings and strengthen your back. Make sure you learn proper form first.