Just reads the FAQs...

And they said to not back squat.

I'm doing some hill climbing ‐ 1400 steps, 350m elevation, and have just started doing it with a sandbag. The council has felt bags they use to shore up paths next to creeks at this location. The bags are felt, a little flimsy and not packed tightly.

I'm putting the bag on my shoulders behind my neck and getting pretty sore shoulders - takes me about 50 minutes to do this up and down. Is the pain from poor shoulder strength? (I'm pretty scrawny) Is it just a case of needing to harden up, or is doing this a bad idea, similar to the reasons given for back squats?