Question
I've been working a physically demanding job for the last year. It involves lifting heavy objects. I've been trying to figure out what's the ideal posture to do it. I usually kneel down to the floor to lift with the strength of my legs. Although I read everywhere that's the right one, some workmates ask me if I got some kind of back problem (I don't know if it's because I work a bit slower or because I curve my back a little bit when I do it), and the tell me to bend my back forward to do it (which I don't do since it doesn't seem healthy).
The only kind of pain I experience is at the base of my neck/upper back and mid-back. I often feel the first one after work and after walking more than a mile or so. It's always a dull pain and I figured it starts because of the weight pushing down my back for hours. One of my work colleagues has a similar pain after work, but he doesn't need to bend his back when working, he just lifts heavy boxes.
Additionally, I experience numbness in my right arm after sitting for too long and not moving. I assume my bad posture when sitting has something to do with it.
Now I wonder what the proper lifting technique is and whether it's normal to feel this kind of dull pain in the upper back/base of the neck after lifting things for 3 hours or so.

Answer
Hello, Ar,

No, pain in the upper back is not normal or necessary.

However, the arm numbness, combined with the pain you've described, suggests a neck injury in your past.

Your way of lifting, using the legs for power, is the healthier way.

Please see this article related to the neck and arm pain:  http://somatics.com/whiplash.htm