Lunges strengthen your core, and a stronger core improves your balance, posture, and eases lower back pain. Lunges also help stretch your hip flexors which can also ease lower back pain.
Alternative #1: Half Lunge
If these are new to you, don’t lower your body down all the way so that your knee is at a 90-degree angle. Instead, lower halfway down or one-fourth of the way down.
Alternative #2: Elevated Surface Knee Dips
If you have bad knees, stand on an elevated surface, such as a box or a step. Have the other foot hanging off the side next to the surface. Bend the knee of the foot that is on the elevated surface. Slowly dip up and down to work on building your muscle above your knee.
Do 5 reps per leg.
Alternative #3: Walking High Knees
If you still are noticing pain in your knees or recovering from a knee injury, do a high knee walk. Walk 10-20 yards, bringing your knee to a 90-degree angle, or as high as you can raise your knee.