Here’s a “controversial” topic: deadlifting to improve the Olympic lifts. The conventional wisdom is that squats are best for improving the Olympic lifts and that the conventional deadlift is a different pulling groove and should not be used, or at least should be used minimally. However, I’ve found that the deadlift and its variations (RDL, snatch grip) are better at increasing my pulling strength than squats. I do try and use a pull similar to the first pull of my clean. This tends to break down as the weight gets heavy, but that doesn’t seem to matter - I get results even if I use a powerlifting deadlift. Am I just weird? [/quote]
I’m the same way. This is most probably (at least in my case) because I’m built to be a natural squatter and a lousy puller. So simply increasing overall pulling strength will transfer to an improvement in the OL whereas a increase in squatting strength (even a significant one) doesn’t do much.
But in general it comes down to the relationship between:
Technical transfer (positive or negative) vs. strength imbalances
An assistance lift can either have a positive technical transfer (improve technique and coordination on the competition lift), a negative one (hurts technique and especially coordination on the competition lifts) or a neutral one (no transfer).
An assistance lift can also improve performance by fixing a strength imbalance (e.g. RDL and deadlifts can strengthen the posterior chain which might be underdevelopped compared to quads if you do not do any pulls but plenty of squats).
So if an assistance lift strengthen more than it negatively affect coordination, there will be a positive performance improvement. But if the negative impact it has on coordination outweight the strengthening effect, the performance will go down.
If your hamstrings, mid back and lower back strength is holding your performance on the competition lifts back, then deadlifts WILL improve your performance on the lifts, even if the coordination pattern is not specific to the competition movements.
If the strength of those muscles is sufficient for optimal performance, then they can have a detrimental effect.
This is why coaches of ELITE LIFTERS often find pulls to be ineffective exercises. At the highest level (WC level) these athletes rarely have weak hamstrings and lower back! And they coordination is so precise that even the slightest negative impact on technique can hurt them. A lot of elite lifters also have ideal body structure for pulling, so they normally don’t benefit as much from deadlifts as they do from squats.
However non-elite lifters will often benefit from general movements aimed at strengthening the hamstrings and lower back.
There is also another issue to consider: the psychological aspect.
A lot of non-elite lifters tend to cut their pull short as soon as they feel that the bar is heavy in their hands. This leads to missed lifts either via insufficient pulling height or pulling the bar forward.
Heavy deadlifts (and even pulls) get you used to holding heavy weights so that the heaviest cleans you attempt feel lighter by comparison and it makes it easy for the non-elite lifter to stay with the pull.
Obviously elite lifters don’t have that problem.