This hamstrings play a small role at the bottom of squats when the pelvis tilts anteriorly. That creates a stretch reflex response at the “Proximal” end, causing the hams to contract, but it’s not an active contraction. The lion’s share of the work is being done by the glutes and the quads. The former pulls the femur back down and pushes the pelvis forward and up. The latter pushes the femur down and back and the tibia up and back.
An exercise that he left out that would get the hamstrings into the shortest possible position is sprinting.
Good find, btw.
There is one thing that Rippetoe left out (actually several because I don't agree with most of his analogies when it comes to squatting) and that's base (foot stance). I'm assuming he's not mentioning it because he uses more of traditional stance. That being said, that tends to make people more quad dominant because you're not recruiting the hamstings nearly as much as if you were going a wider stance. Wider stance (wider than shoulder width) will infact recruit much more of the entire posterior chain than the more traditional squat.
If we get into the knee pain debate, IMO, it's because of weak hamstrings (quad dominance) since the hamstrings are a flexor to the knee. When it comes to the stretch-short cycle (we train the shit of it) again, IMO, can be seen in two ways and regardless of which ways, you're still utilizing stored elastic energy.
1. In a squat, using submaximal weights (55-70%) with a 3-0-1 tempo or adding bands at less percentage using a 2-0-1 tempo
2. Plyo's would be just one of the best examples of SSC utilizing stored elastic energy. But there's many forms of plyometrics, not just box jumps
As seen here..
https://instagram.com/p/Bb2TF3lBQJW/
