Lifting a baby from a crib, changing the water in the pets bowl, taking a suitcase off a carousel, and pulling weeds in the garden all require a similar and yet elusive biomechanical engagement.
Take a look at the woman bending over to soon lift her child. To get there from the upright position she bent at the hip joints, tipping the top of her pelvis forward and sending it backwards, lowering her pubic bone and sending her tailbone up and behind her.
To return upright safely and efficiently she would send her pelvis forward, using the abdominal muscles to pull the pubic bone up and forward, and the buttock muscles to help her tailbone to push the pelvis forward. The abdominal and buttock muscles working together is the strongest force couple in the human body.
The most significant aspect of safe lifting is to initiate the return to the upright by pushing from the pelvis (tucking the tailbone ). I cannot overemphasize the importance of avoiding the tendency to initiate the return to the upright by lifting the arms and torso first— Instead use the power of the hips and save the back!