Yes, very helpful. My DH husband worked for B&Q when he retired and he had manual lifting training.
I've pulled a muscle in my back (not too bad luckily) and I did it sitting on a bench during a school assembly. I did think of asking for a chair, I was easily the oldest person in the building. I was the nan, but didn't want to make a fuss.
Next time, I will definitely find a chair or stand by the wall 
I'm wary of yoga and pilates because I know of friends who pulled muscles by being over zealous and that is one of my worst traits. I really go for exercise and can't seem to stop myself so I'm keeping away from it.
I can walk for miles, carrying heavy bags of shopping and that's not a problem. It's sitting in an awkward position or twisting awkwardly that does the damage. I always make sure the bags are of equal weight.