The Survival Book, by Anthony Greenbank, recently reissued has a section on this issue. There's a drawing showing how to position your arms and lift your legs to avoid falling under the surging crowd. It works. Many years ago I was in Times Square for New year's Eve. Crowd got a bit dense and was moving. Just for the heck of it, I briefly bent my arms, stuck out my elbows and lifted my feet. I was held-up by the crowd and even moved with it for a very short time. I was impressed enough with this experience to remember it for the last 40+ years.