Wikipedia
The good-morning is a weight-lifting exercise. It is known as a good morning because of the movement in the erector spinae which resembles the rise out of bed to stretch. The erector spinae muscles of the lower back work isometrically to keep the spine in an extended position while the hamstrings and gluteus maximus work isotonically to perform hip extension. Other muscles are involved in stabilizing weight on the back and maintaining balance.
The degree of knee bend used will change the focus. The straighter the knees, the more the hamstrings are stretched and stressed by the movement and this stretch involves them more as the hip extensors. Bent knees can shift the weight forward, which allows the pelvis to drift back further as the body hinges in hip flexion.
Usage examples of "good-morning".
Buried in silence and shadow, delightfully stretched beneath your warm eider-down coverlets, we will slowly enjoy the happiness of being together, and we will wish one another good-morning only on the stroke of noon.
Mrs Cakebread had fancied herself insulted, by my saying good-morning to the kitchen-maid and the knife-boy before I said it to her.
He punched a button on his sonic fish-finder and the screen blinked a bright green digital good-morning.