What i'd like to know is what muscles are good for lockout in sumo deads. Will do some rack pulls, chains or bands if and when i get the opportunity. any help would be much appreciated.
Thats unusual usually locking out the sumo is the easy part but getting it off the floor is hard,perhaps your form needs work? To pull big in any style a thick strong back is what you need so train that more from your erectors to your lats and traps.
Glutes glutes glutes glutes
It's lower back and hip flexors you need to strengthen.
What's the reasoning behind recommending those muscles?
You only have to pull sumo to find out. The better the suit, the stronger they need to be.
I would say its more likely to be form, although we would need to see a vid of you deadlifting to be sure. My sumo lockout is a bit hit or miss at the moment and its all to do with falling forward and letting the weight hang me about 4" from the top. Am doing 3 things to remedy this: 1) loads of good mornings, GHR, and conventional stance work (RDL, Racks and blocks) to get the back worked hard. Few sets of concentrated work after box squatting on a thursday and my lockout is really coming along working on. Read about some finnish deadlift training on WSB site recently and over there the sumo pullers still do at least 50-60% of their training in a narrow/conventional stance. Lash in some chains, bands etc and see what works and what doesn't. 2) doing much lighter training for sumo. No belt/high rep i.e. 10 consectutive singles where I setup, grip, pull, set down, let go and repeat 10 times (really like WSB 6-10 singles with 30 seconds in between, i just dont time myself). Currently doing 1 set after conventional work as keeps the technique when concentrating on strengthening my conventional. I keep the head pulled back and rock into the bar. This forces the hips forward and shoulders back helping keep the bar in tight and making it easier to complete. total weight is not the issue here, pulling the bar with max force to teach fast muscle recruitment and form are kings. 3) strongman stuff for GPP. I've got farmers walks, a nice 110kg atlas stone and 80kg sandbag. Also getting into a 100kg barrel and going to experiment with zerchers. All this is round back lifting for reps at its best.....really hits the back in a way that a barbell can't and is helping ALOT with overall toughness. I put something interesting in as a finisher on Thur after deadlifting (loving my atlas stone at the moment!) and then 2 more on a Sat.