Easy Lumbar Stretches (Quadratus Lumborum/Erector Spinae)
Lie on your back and bend one leg. Hug your knee and pull towards your chest. Hold for 15 seconds. You should feel this stretch in your lower back, and maybe in the back of your leg and buttock. Perform 2 reps and do the other leg. Next, starting with the first leg, pull the knee up and towards the opposite shoulder. You should feel this stretch a little lower, in the sacro-iliac area. Again, hold each stretch for 15 seconds, two times per side.