This is gonna be quick..rather than answer a Q on fb..might as well write in on here quickly where it'll be more accessible......if it sucks..shoot me.. I'm brutal at writing when I don't rush it or when I edit it...
Here's a video of a recent squat practice. I hadn't squatted in a while because of an injured back from deadlifting(serratus posterior inferior) and my knee had been acting up again trying to do volume training in the 80% 1RM range so this day I worked up to a heavy single(675) to see how it would feel and then I did 1 downset(635x3) followed by 5 'practice sets of 500x5 sets of 3 reps performed at a 4:1:1 tempo.
Why was I doing the tempo squat and why was I using that particular tempo?
Normally I like to do my explosive 25 minute "CAT Game" when I'm not lifting heavy but a couple factors said not to:
1) My back wasn't 100% yet so I didn't want any jerkiness at the bottom...GOing down slowly would eliminate this.
2) My knees have been acting up a bit since I did a lot of volume in the 80% range a couple weeks ago..so I'm not lifting heavy...and I cant lift too aggressively....what else can I do? And how can I get better with light weights...the only real option is to treat it as a practice.
Normally(healthy), these phases are performed:
Eccentric: As fast as possible on the way down while still maintaining tension and technique
Amortization: ZERO, change directions as fast as possible without bouncing, and whilst maintain proper mechanics.
Concentric: Accelerate, aggressive, maximal effort...
Now...while squatting being a china cabinet pussy cat bitch...
ECCENTRIC: How else to practice going down perfectly than to do it slowly so that you can pay attention to micro aspects of the lift. I can pay attention to my posture(spinal alignment), torso angle, feel the tension in the quads and hamstrings, and pay more attention to where the weight is on my feet. When going down very slowly you can make the adjustments easily....like driving slowly. And you can feel the tension build. 3-5 seconds is what made most sense to me...3 seemed borderline short and 5 sounded miserable... so 4. This allows me to pay a lot of attention to my back issue by really focusing on perfect posture and amortization... and it also allows me to keep weight on my entire foot a little better and tension in my hamstrings.
AMORTIZATION: I have noticed that with my squat sometimes I rely too heavily on my quads and don't necessarily pay attention to my hamstring tension. Even though I maintain my pelvis at the bottom I often tend to 'bounce' out when it gets heavy or I get lazy. The pause eliminates this. The beauty with the pause squat is that the second you try to stand up, you immediately know whether or not you maintained tension everywhere...its instant feedback...you either stand up nicely or you body has to re-engage muscles to find tension and you tidal wave yourself to the top. I don't train the pause very often but i definitely see value in it. If I were doing straight pause squats I would be perfomring them at a normal decent pace and pausing for 2-3 seconds. Since I am descending at a 4 count to practice control and tension building, a 2-3 second pause, might make me pass out... I really just needed to address the things above which a 'full stop' or 1 count would address.
CONCENTRIC: Unless bodybuilding, I can't think of a reason to not stand up as fast as possible.
Hope that helped... I know its not scientific..but i'm working around bullshit injuries.
*** I have to mention that:
1) This is not something I do often...
2) IMO doing these too often can mess up your TIMING....and TIMING IS VERY IMPORTANT.