I think this is another study that is not quite what it seems. As someone else had mentioned, the actual speed of the movement was not controlled for, which makes it likely that the quarter squat group was treating the exercise perhaps as an explosive movement.
The problem, in my opinion, is Time. The length of the study is not sufficient. As a general rule, dynamic exercises will have a greater positive transfer to dynamic activities, especially over the short period of time. For example, If someone gave me an athlete that could be a beginner or intermediate, and I have two weeks to get them ready for a vert test and 60meter test, and I was given two scenarios: (let’s also assume that in each scenario, the actual practice of the events themselves are allowed)
- use only plyos
- use only medium-heavy weights
There is no question in my mind I would go with 1
But if the same question is posed and I have 36 weeks, there is no question in my mind i’m going with 2
You can reach a reasonably high level of elastic/reactive abilities fairly quickly, which in turn will create a quick transfer. On the contrary, while one can improve strength quickly, the amount of strength necessary to improve other motor qualities is likely to be greater and take a longer time.
So when I read this study, that is essentially what it says to me.
In regards to hamstring recruitment, the highest level is NOT in a Quarter squat. It is also NOT in a rock bottom. It is right in between or perhaps what most people might consider a powerlifting squat (hip crease at same level as top of patella).
Any higher or lower and there will be a comparatively smaller external moment arm acting on the hip.
So IMO (assuming I follow Charlie’s approach of strength training being General) if this study were done long term with every variable controlled for, the powerlifting squat would yield higher results.
But then again, a coach is welcome to implement squats to varying depths, the problem I see however, is most coaches just doing quarter or higher squats. And I believe that to be a mistake.
(edit: crappy spelling, there’s probably more but oh well)