It is a good thing before having the toddler in my life, I spent time in the gym learning to squat. I find that I use the kettle bell squatting form in picking her up. Bend the knees down such my thighs are parallel to the ground, pull her into my chest, and push up with the legs. The goal is to keep the back straight and carry the load of the kid vertically along the spine as it was designed. Pulling the spine horizontally will cause back pain. Kettle bells do not squirm.
Of course, the day after Leg Day, it is silent pain to pick her up.
And, being older, I ought to make sure to protect my back.