When I conducted my EMG research, I was surprised to find that squats elicited more lumbar erector activity than deadlifts. Not surprising was that deadlifts elicit more thoracic erector activity than squats. In powerlifting competitions, you squat, then bench, then deadlift. Most recreational lifters always squat before they deadlift as they feel that squats “warm them up” for heavy deadlifting. This makes sense as many individuals hurt their low backs when deadlifting because they aren’t warmed up sufficiently. The squats also provide for more range of motion at the hip, knee, and ankle joints, so it makes perfect sense to squat prior to deadlifting rather than the other way around.
Many find that they are stronger at deadlifts when they squat first. Conversely, if they deadlift before they squat, they find that their squat is considerably weaker. So I feel that if you’re going to squat and deadlift, it makes more sense to squat first and deadlift second. I’ve always done it this way in my training and coaching.
Need more evidence about lumbar erector activity in squats vs. deadlift? Click on this link. This might have to do with greater pelvic tilt moments in the squat as opposed to lumbar moments.
It’s an abstract from a 2007 Journal of Strength and Conditioning study that shows that when using an 80% of 1RM load in the squat and deadlift, the squat activates 34.5% more lumbar erector activity than deadlifts while the deadlift activates 12.9% more thoracic erector activity than squats. Interestingly, this study showed that powerlifters were able to control the lumbar spine and prevent flexion in the squat but not the deadlift.
The kinematics of a squat and deadlift are very complex but if you squat and deadlift in a speedo your form will magically perfect itself!