I see many lifters engaging the wrong back muscles on the Deadlift. They use their rhomboids which are stabilizer muscles of the shoulders instead of the lats. Think about spreading your shoulders then squeezing your armpits to engage tour lats. So your upper back will be spread and your arms are long.
When you are pulling the slack out of the bar think about pulling your shoulder blades into your back pocket not bringing them together. Lats are some of the biggest and strongest muscles in the body so it is crucial we use them. This is why we program lots of back work in powerlifting. Strong Lats equal strong bench, squat, and deadlift!
If you are interested in learning more we are holding numerous powerlifting Clinics and courses over the next few months.