Stiff legged deadlift: locked knees or not?

[AutoKal47]

I've never had probs with stiff leg dl, actually i like that exercise a lot,
and I can even use some weight on it, and because of that I recently started
to question whether or not you should actually lock your knees when doing it or not
I read around but opinions are like 50%, some says stiff leg should be slightly bent knees,
and straight leg instead should be locked..
Name aside, I'm interested in knowing if doing it with locked knees can be dangerous or not
opinions?

 

[Frank Reynolds]

I've never had probs with stiff leg dl, actually i like that exercise a lot,
and I can even use some weight on it, and because of that I recently started
to question whether or not you should actually lock your knees when doing it or not
I read around but opinions are like 50%, some says stiff leg should be slightly bent knees,
and straight leg instead should be locked..
Name aside, I'm interested in knowing if doing it with locked knees can be dangerous or not
opinions?

I always keep them just shy of locked. I do more RDL than SLDL though.

 

[AutoKal47]

I always keep them just shy of locked. I do more RDL than SLDL though.

Hey bro

I do both, different days, but I find with locked knees I hit hamstrings more, knees slightly bent I feel it
in my lower back..
I just wanna make sure there's not some unwritten rule about not locking your knees that I'm not aware of

 

[0071982WC]

Hey bro

I do both, different days, but I find with locked knees I hit hamstrings more, knees slightly bent I feel it
in my lower back..
I just wanna make sure there's not some unwritten rule about not locking your knees that I'm not aware of

I prefer doing mine with knees locked..... Feel them much better in the hams that way. 225 for sets of 15-20 are the sweet spot for me.

 

[Rahl]

I go just before lock and feel them in the hams just fine. I try never to look the knees.

 

[ZiR RED]

Most people I see doing them with locked knees are incorporating a lot more spinal flexion and extension that rotating at the hip. The spine should act as a stiff lever, not a series of small blocks changing angles. I find that when the knees are locked you are not able to push your hips back far enough, the weight then is further away from the center of gravity, thus limiting overall hip flexion and hamstring involvement.

Keeping the knees slightly bent allows you to push the hips back further, keep the weight close to the center of gravity, maintain a spine rigid (i.e.: flat back) and thus use the hamstrings to rotate the load around the thigh.

Check out the differences, even though both maintain a flat back:

Locked, see how far away from the body the weight is and how much more the spine needs to support:

Unlocked, see how close the weight is to the center of gravity, thus less work on the spinal erectors and more on the hamstrings:

Granted the video below is of the good morning, but you can see the slack at the hammies when the knees are locked. Check the video, its actually a really good animation and analysis.

Good Morning Exercise - bent knee - YouTube

Br

 

[AutoKal47]

Most people I see doing them with locked knees are incorporating a lot more spinal flexion and extension that rotating at the hip. The spine should act as a stiff lever, not a series of small blocks changing angles. I find that when the knees are locked you are not able to push your hips back far enough, the weight then is further away from the center of gravity, thus limiting overall hip flexion and hamstring involvement.

Keeping the knees slightly bent allows you to push the hips back further, keep the weight close to the center of gravity, maintain a spine rigid (i.e.: flat back) and thus use the hamstrings to rotate the load around the thigh.

Check out the differences, even though both maintain a flat back:

Locked, see how far away from the body the weight is and how much more the spine needs to support:
View attachment 55415

Unlocked, see how close the weight is to the center of gravity, thus less work on the spinal erectors and more on the hamstrings:
View attachment 55416

Granted the video below is of the good morning, but you can see the slack at the hammies when the knees are locked. Check the video, its actually a really good animation and analysis.

Good Morning Exercise - bent knee - YouTube

Br

Being able to keep the weight close is what made me wonder in the first place,
great post, rep'd

 

[TankShift]

I go just shy of locked, but fixed. I also started using dumbells. They can get closer to the side of the legs, less stress on the back.