This advice is too good not to have members take notice. it's also a common problem, so i'm leaving it up here for a bit.
coolcolj said:situps? That means you have tight hip flexors and posas - situps make it worse, combined with all the sitting you do
Stop doing situps!!
Tight hip flexors, inhibt the glute from firing, so the lower back starts to become over active. Your glutes should feel it when you walk, not your lowr back. I.ve been there before
try this in the morning and after anytime you sit for a while and before training to
lossen up the hip flexors and activate the glutes, which will reelas pressure off your back. The glute should do all the work
do a quad/hip flexor stretch like this at medium intensity
http://www.sport-fitness-advisor.com/images/golf_stretching_quad.gif
after about 20secs, you should feel your hip flexors start to relax. You keep holding the stretch after the 20secs, and the start contracting the glutes at moderate intensity so the upper thigh moves back slightly - hip extension - but you only contract briefly. Relax the contraction, while still holding the stretch, the upper thigh will move back, forward a little, and repeat the contraction 20 times. Then do the other leg
When I've been sitting a while and I do this move, straight after, my lower back feels all relaxed and nice and my glutes take over an do all the work when I stand or bend over. Where I normally might have my lower back feel all tensed and strained. Everyone can benefit from this move as we all sit quite a bit...
Works great before a squat and deadlift session to get the glutes firing