Help! My back keeps bending during deads and rows

[Yarg!]

Help me out here guys, I dont know what I am doing wrong. I am sticking my ass out and sort off putting my head up as I am doing bent over barbell rows and deads, and still my back bends over (pretty badly too.) Could this be because this is my first time doing deads and barbell rows? Up to this point I've only been doing lat pull downs and cable lat rows for lats. Will my back stop bending as my body "adapts" to these exersises? Also, fortunately I am not feeling pain as I am doing these exersises with my back bent, but that doesnt mean I am going to keep doing them this way. Thanks guys, your replies will be much appreciated.

 

[IronLion]

your erectors are weak, just lighten up the deads and start working on good mornings and stiff leg deadlifts

 

[Yarg!]

Thanks dude, will work on those good mornings.

 

[Screwball]

Could be a lack of flexibility in the hip flexors, erectors and/or hamstrings.

Could be weak muscle groups in the erectors, obliques and/or abdominals.

Could be a lot of things... Know your body and work your weaknesses.