The latissimus dorsi is the body's largest back muscle with attachments at the humerus, scapulae, rib cage, and pelvis. It provides a ton of stability to the spine during heavy loading. Use these two cues to further engage your lats:

1. Protect your armpits.
2. Squeeze an orange in your armpit.

Both work well, but sometimes it's advantageous to go a step further in order to help someone feel what it's like to fire the lats. Try this:

Learning Lat Tension with the Deadlift

Simply add a resistance band to a barbell and do your deadlift while keeping the barbell close to the body at all times. You'll get it immediately.