It is sort of funny to read what scholars have to say about the topic of VJ training. I am extremely skeptical towards this information because it is usually based on poorly designed research with limited application value. The information in the article is really shallow, especially regarding appropriate training design. It is just stating conventional wisdom and many points can be debated. I heavily disagree with the standard advice to use a periodization model for everything regardless of training level and I think this is just a waste of time and display of a poor understanding of what will be necessary for example for an athlete without previous exposure to strength training.
The hesitancy on the topic of heavy vs. light loads for strength training I find especially amusing. Those guys are seriously suggesting that it MIGHT be good to let an athlete do "strength" training with <70% of his 1rm? This MIGHT be better because it does not take as long to lift the load? There are so many things wrong and illogical about this thought, that not even the opposite is true and one has to doubt if those people have actually put any thought into this instead of blindly adopting things others have said before to give apology for their idiotic research.
Regarding squat strength: Lifting a heavy weight will slow the lift down. A 1rm will look rather slow for the squat, otherwise it is not a 1rm. The last 1 or 2 reps of a 5rm might look rather similar. Here is the thing though: After you got those last 2 rather slow reps, you might next time be able to do the same number of reps with 5 lbs more and in a month you might have a 5rm considerably heavier than previously. The last reps of that new 5rm will still look slow, but how does the set look like with your previous 5rm weight? Probably not so slow anymore - I think everyone can follow that thought. Now, will that squat strength transfer to gains in the VJ? No, not if the guy training is in fact more advanced than a novice strength trainee. But we are doing resisted explosive lifts, right? See, they do take care of that problem ridiculously well if used correctly. What happened during the heavy training though is that we gained strength and muscle which makes progress in the explosive lifts a lot easier which in turn helps with jumping tremendously.
Now, when we would instead have trained with super light weights, what would have happened is that maybe we would have gotten a little stronger and that strength might even be relatively transferable to a VJ. But the gains would have been vastly inferior considering the trainee did stall in a power phase earlier on. The reason being that max strength, a necessary component of power, would still be a limiting factor.
