Plank

Question: If I have a lower back pain while front planking, does that mean I do something wrong?
 * Unless your form is off (swaybacked or arched) It's basically a sign that your core is weak and you need to do more plank
 * You might consider planking on an inclined surface at an angle that stresses but doesn't hurt your back, and declining from there.
 * I squeeze my glutes during planks, and it takes the pressure off my lower back area.
 * I'd suggest doing things like V-ups, bicycles, and Russian twists to focus on your belly muscles, they will support your body eventually and take the pressure off of your lower back.
 * Also, start doing RKC planks, probably 3-5 every other day or so, and stop doing front planks for a couple of weeks until you build up some strength. I have to also stretch by lying on my back and gently pulling my knees up near my rib cage to let that lower back ease out.

See also:
 * the 5-minute plank workout from Physical Living.