First, if you pause to remove the stretcth reflex, it is not plyometric anymore. In fact, eve if you don’t pause it might not be plyometric. To be plyometric, and action must:
- Have an important storage of potential energy from the absorption phase (which typically only happens when you have to SUDDENLY absorb a force and this occurs mostly when the muscle is relaxes/not under load and has to quickly turn on upon impact)
- Has a very short ground contact time, less than 250 milliseconds. More than that and the plyometric effect is lost.
So, pausing in the bottom is the best way to make sure that a movement will not be plyometric.
Now, that doesn’t mean that this type of exercise doesn’t work, it does (to build explosiveness).
See, muscle power is produced by three main factors:
- Voluntary muscle contraction
- Elasticity of the muscles and tendons
- Plyometric effect (storage of potential energy to be used subsequently)
Each type of jump/throw/power training will involve 1 or more of these factors to varying degrees. Pausing, or using a softer surface will increase the reliance on the muscle contraction factor while decreasing (or removing) the others.
Paused explosive work is very effective a developing the capacity of the muscles to produce force explosively. But it’s not plyometric.
But the more important question is whether this type of training will help you lift bigger weights.
Two main things to consider:
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Strength gains are velocity-specific: you get stronger at he velocity you are training. The further away the speed of an exercise is to that of another movement, the less transfer there is.
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Explosive training can increase the conversion of IIa fibers into IIx, or, more accurately it better maintains IIx fibers, preventing them from converting to IIa. But is that really a good thing for strength? If your goal is to be maximally explosive (sprinting, jumping, hitting, changing directions, etc) having more IIx and less IIa might be a good thing. But for IIa fibers are actually better suited to strength work. Think about it: when you train for strength, IIx fibers convert to IIa fibers. The body always adapts to be better at what you ask it to do. So if strength training converts IIx fibers into IIa, that’s likey that IIa are more effective fiber during strength movements.
IIa are just as strong as the IIx, but are more resilient to fatigue. Yes, they are a bit less “explosive”, but strength is not dependant on that. A max effort often requires grinding the weight up, and IIa fibers will be better at that.
As for strength gains being velocity-specific. The main reason is that the firing pattern is different between explosive actions and strength actions.
Here’s what muscle recruitment looks like during explosive actions (keep in mind that this happens VERY quickly):
- The primer movers and synergists (agonists) fire to produce a burst of acceleration. During that time the agonist (opposing muscles) relax. This is because agonist and antagonist co-contractions is great for joint stability but bad for speed production (as you are fighting against the resistance AND opposing muscles). To favor acceleration the body relaxes antagonist muscles because acceleration is favorer over stability during those fast movements.
- Then there is a relaxation of the primer movers/synergists and a quick activation of the antagonist. This is to create some stability when the initial acceleration is created.
- Finally, there is a second burst of primer movers/synergist activation along with a relaxation of the opposing/antagonist muscles to reach top speed.
Compare that to what happens during slower, heavier tasks:
Here we only have one phase: during heavy lifts, joint stability is favored over acceleration (the more stable you are, the more force you can produce). So the prime movers/synergists (agonist) are firing hard throughout and there is a background co-contraction of the antagonist to provide more stability.
What does that mean? It means that neurologically, both types of actions are quite different. You can be really good at one and bad at the other. And improving one doesn’t automatically mean that the other will improve.
Will explosive push-ups and jumps improve maximal strength? Probably not. At least not if you are already pretty well-trained. It might have indirect effects by improving the capacity of the central nervous system to send a strong activation signal to the muscles and maybe the muscle’s responsiveness to that signal. So it’s certainly not a complete waste.
But if your goal is to get stronger, it is probably not going to give you what you want. If you were an athlete who needs to be explosive or explosive and strong, it would be more beneficial. But for pure strength, it will be a bit limited.