Correct form and technique in single leg db deadlifts in detail

Question

What is the correct form and technique for the single leg db deadlift in detail? I also want to know why one should do it in this way and not differently. What are common mistakes when doing this, why are they harmful and how to fix them.

If there are reasonable technique variations please also mention it and explain the how and why.

Over the web there you can see pictures of multiple different forms which makes you unsure whats correct and whats not. Take for example this picture:

You can see that the standing leg is slightly bend and that the arms are not perpendicular to the ground (as it would be the case in a normal deadlift). However perhaps this makes sense for the single leg deadlift, I don't know.

In the next picture the arms are perpendicular to the ground:

In the next picture only one dumbbell is used and the standing leg is straight:

However I also found images where the dumbbell is in the hand on the side of the standing leg:

I also found this variation which seems to be similar to the regular deadlift:

Is there a rough rule of thumb which gives a relation between the weight you can use in a regular deadlift and that one you can use in a db single leg deadlift?

Answer 1

I have used the Single Leg Dumbbell Lift (SLDL) extensively during the last year to improve running performance. In my opinion, there IS a correct technique to this exercise that is motivated by the GOAL of the exercise.

In my case, the primary goal of this exercise was to improve lateral stability and balance throughout the ankle, knee, and hip, while increasing flexibility. The secondary goal was to increase strength.

Therefore, the "right" technique is one that best promotes the development of stability, balance, and flexibility. To me, photos 1, 2, and 3 all meet my definition of the "right" technique. In photos 4, and 5, the individual may be able to lift more weight, but they will not be getting the stability and flexibility benefits.

Specifically, I recommend the following for this exercise:

1. Keep back flat.
2. Standing leg slightly bent.
3. During the "bend" don't let the lifted leg droop down (like the man in photo 4).
4. On the recovery phase of each rep, try not to let the lifted foot touch the ground so that you are balancing on one foot for the whole set (this is harder than it sounds).
5. Use light weights (or even no weights) until you can complete a full set without losing your balance and maintain good form throughout.
6. Don't let the weights rest on the ground during the "bend".

(1) and (2) promote good flexibility. (3) through (6) promote stability and balance.

The tendency when we get tired or lazy is to droop the lifted leg and/or allow the weights to rest on the ground during the bending portion of the exercise. The other tendency is to use too much weight, which subsequently requires us to put the lifted foot on the ground in between reps.

I don't stress about weights in one hand or two. . . I say switch it up to get some variability in the exercise.

My best suggestions for correcting these errors are to 1) don't use any weight (at least at first), and 2) use a mirror - your back and lifted leg should be parallel to the ground during the "bend" portion of the exercise.

SUMMARY

• Photos 1 - 3 are the right technique.
• The right technique is motivated by developing lateral stability and balance throughout the ankles, knees, and hips.
• Common errors: too much weight, drooping leg, letting weights rest on the ground, and putting lifted foot on the ground between reps.
• Technique Fixes: Lose the weight, use a mirror.

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By thy way, my running form improved noticeably last year thanks in no small part to this exercise.

Answer 2

In terms of the muscles worked out the bend of the leg in the air should not matter too much, you should try to keep it still though (don't use it for momentum).

IMO you should have the leg up on the opposite side of your arm for better balance. The first person has weights in both hands which is better once you start to get to the heavier weights for balance. The last person seems to be doing a beginers version of the exercise because she lacks the balance to lift her leg off the ground. My suggestion would be to follow the form of the first one. If you have trouble doing it the last one should be easiest.

For the last part of your question I'm not sure if your reffering to a barbell deadlift or one with a kettlebell. But I can tell you either way your one legged deadlift will be significantly less possibly by over 100 pounds depending how high your deadlift is.

For my lifting reference i use exrx, here is a reference to a single leg stiff-leg deadlift