OCG wrote: ↑Tue Dec 19, 2017 9:30 pm2. "Hip drive" can also be cued as "leg drive" or "using your quads". It's simply a cue intended to counteract the chest/bar drive and keep the torso angle fixed out of the bottom. I feel like a proper "chest drive" is severely underrated and under discussed around certain parts, but that's another topic. As to what degree of back angle loss is acceptable, that's a bit more of a squishy thing I think. Perhaps we can take bar speed or smoothness of the lift? If you start learning forwards enough the bar slows, it's bad?
Regarding the first: I think OCG is right on. "Hip Drive", "Chest up" etc, etc seem to all correct something regarding relative rates of opening at the hip and knee joints vs rate of vertical bar displacement. I'm too dumb to articulate what the ideal relationship in the rates should be. I might be completely off base, but I think I intuitively look for jacked up rates of joint opening and bar displacement when cueing "hips" or "chest".
Regarding the second: Yes! Once a lifter gets the basics down, torso rigidity is of prime importance (it's so important that its mention demands italics and bold font). I don't think it's possible to overstate the importance of an absolutely rigid torso. It's also incredibly difficult to coach. I'll try to tease out some cues for 1) upper back isometric contraction and 2) valsalva.
For now, I'll simply repeat what I've said before: the 30-50 seconds of trunk bracing in a squat set should rank among the most taxing volitional efforts of your life. Literally. Every time. (I fail at achieving this on almost every set). I think every major breakthrough I've had with press, dead and squat mechanics has started with an ever more rigid torso. In brief: if it helps, replace the oft-repeated "Tight, tight, tight" with "most intense volitional effort of my life*".
* I don't think the knee and hip extension in a squat are "volitional effort". Muscle spindles stretch, motor units are appropriately recruited (or if fatigued....not); there's an automatic quality to hip and knee extension. But the bracing in a squat (the upper back isometric contraction and valsalva) is pure, unrelenting intention.