Conventional vs. Sumo Deadlifts

Bigger Stronger Leaner Powerlifting & Strength Sports
1


Hello everyone,

This is just an informative post in which I try to clarify the trade-offs between the conventional and sumo deadlifts. I was watching some deadlift videos on youtube and some of the comments I read were just plain stupid. I have nothing against either lift. I have personally switched over to sumo deadlift because it’s a more favorable back angle for my thin mid section and I can pull heavier. I still train both.

I believe people should do whichever they feel they are strongest at. The comment that annoys the shit out of me is people saying that sumo deadlifts are way easier than conventional deadlifts. Let’s get into the mechanics of conventional vs. sumo to see what the actual trade-offs are.

For simplicity, I will only analyze the lower body portion. We can discuss the back angle, moment of inertia in the mid section, and bending moment experienced in the upper body if need be. By analyzing the legs using a free body diagram, we can determine the difference in work and the amount of force generated in the legs for both styles. The angle of the legs relative to vertical will be defined as Theta. Work is equal to force x length.

For conventional, Work = Weight x Distance. For sumo, the distance traveled is Distance x cosine(Theta). So for sumo, Work = Weight x Distance x cosine(Theta). I think everyone knows this portion. Now here’s the second part of the analysis that most people forget, the force generated in the legs. For conventional, the force in the leg is about equal to the weight being pulled since the force is applied in the same direction that the weight is moving (up), that means Leg Force = Weight.

For sumo, the force is applied at an angle so in order to move the weight up, more force has to be applied compared to the weight. This means that Leg Force = Weight x secant(Theta). We can turn these numbers into ratios to see the relative comparison.

Work Comparison
Sumo / Conventional = cosine(Theta)

Leg Force Comparison
Sumo / Conventional = secant(Theta)

For me, I have a leg angle of 25 degrees. So by switching to sumo, I reduce work by 9.4% but increase leg force by 10.3%. For some people who use a wider angle of 30 degrees, they reduce work by 13.3% but increase leg force by 15.5%. I want to point this out that even though a person does less work doing sumo, they have to generate more force to do less work.

That is why you see a split between styles for world record holders. They do what is advantageous for them while still being within the powerlifting rules. The graph at the top shows how work decreases and leg force increases with respect to the leg angle (ranging from 0 to 90 degrees or 0 to 0.5Pi).

2

Don’t pay attention to Youtube commenters? I thought this was common knowledge by now.

I, for one, am significantly weaker with sumo. And every powerlifter is well aware that your personal leverages are what affect which style suits you best/which is easier/harder.

3

interesting read, thank you.

4

Yeah very interesting. Would never have known any of that. I was expecting another post bashing one or the other hahaha. Thanks

5

I’ve always been a conventional deadlifter. You know what’s funny though, is every time a friend or family member, who doesn’t lift at all, wants to try lifting one of my deadlift setups, they always do so sumo style. Must be something to it.

6

My weight on both of them are about even right now so I’m going to be taking this into consideration for what one to focus on. Thanks this is really good stuff.

7

The stronger one is whichever one I train more. But my hips don’t appreciate sumo and my back is pretty sturdy so I go with conventional.

8

Mine are pretty much the same but I do conventional almost all the time. When I do sumo my hands slide against my thighs and thats pretty annoying, especially when I get chalk all over my shorts.

9

I thought about what I posted and I probably oversimplified the analysis. I did the free body diagram for when both lifts are at the top position. At the bottom position for conventional, the force in the leg is still equal to the weight being lifted. The bottom position for sumo actually requires more force since Theta is greater.

The calculated work is still the same. If Theta equals 40-45 degrees at the bottom position, the leg force ranges from 31% - 41% greater than the leg force required for conventional. The leg force reduces throughout the range of motion as Theta decreases. It’s more important to note that although the leg force is greater at the bottom position for sumo, the legs are also at a more favorable strength position since they are more extended compared to the leg position at the start of conventional.

How easy that part of the lift is for a person depends on how their strength curve looks throughout their leg extension. So again that is another trade-off. It would be interesting if someone invented a variable force leg press machine that could output the lifters’ strength curve along each position of the leg extension. That theory could probably be applied to other lifts as well. It’s a similar concept to using bands since you vary force along the entire movement but it would be cool to know an individual’s own strength curve.

10

I know that with sumo if I can’t make the lift I won’t break the ground or just go up an inch or two, but with conventional it’ll go to mid shin to knee height before stalling.

11

Hmmm, no wonder I hear a lot of sumo lifters say that they can finish the lift if they break the floor. I’ll have to experiment with reverse band sumo in the future to focus on that portion of the lift.

12

Thank you for this. I have had to switch to sumo. I’ve had some past back issues, and it works better for my body type. Great info.