chest up ass back will definitely increase your rom and maintain straight back, and let your knees go where they will go... usually the comfort spot. I tried a lot of foot positioning and stance width ... the sweet spot for me is about shoulder width feet slightly pointed out. RDL's are awesome and have helped my DL big time. But have fun with them cause that is what this is all about, for me anyway.I like them, I struggle a lot with the form...its a work in progress so I've dropped the weight considerably and we've also added in corrective holds to try and improve mobility/flexibility which in turn should improve form & ROM. I'm quite tall and have very poor flexibility which means back generally rounds & ROM with good form is very short.