[quote]OBoile wrote:
[quote]mertdawg wrote:
Theoretically there is enough energy stored in lowering a squat to almost raise it. If you drop a weight on a trampoline it will rise to the same level minus the inefficiency. Unless the weight is great enough to damage the trampoline.
[/quote]
I don’t think there is anywhere near enough energy stored to “almost” raise a squat. Humans are far less efficient at storing energy than a trampoline. IIRC, with the stretch reflex, the energy stored is typically like 15-30%.[/quote]
The flexed muscle-tendon apparatus is physically speaking a highly elastic material but of course there is heat produced, and also heat lost to mechanical inefficiency (energy dispersed into the core during a squat) but I think that when you get a maximal force for a given individual, say someone maxing 300 on the bench, the force caused the reflexes to balk at maintaining (continuously) the contraction needed to elastically rebound the weight. The muscles become less elastic under that force to prevent damage. Maybe its 30% efficient. I think if you take a fairly light weight, say 135 and stay tight, a good chunk of the work done in raising the weight came from the lowing of the weight if you can lower the weight (at the end) at the same speed that gravity would give it falling from the lockout.
The stretch reflex is something different. It is about raising force production reflexively. People have come to confuse the stretch reflex with storing energy during the descent. A trampoline has no stretch reflex (or maybe it does, I’ll explain) but it stores the energy.
A muscle may store the energy but not have an increase in maximal force potential.
My theory, or at least conjecture is that the stretch reflex may not actually be an increase in stimulation, but rather just a decrease in inhibition. When you lower a weight, if the force is too high, or too high for too long you have a “reflex” that inhibits maximal force, so the 300 pound bench presser may vary well be able to exert 360 pounds of force, but the reflexes shut that down to protect. If the force rises fast enough though (ballistic reversal) the muscle starts contracting at 360 pounds of force BEFORE the reflexes kick in to reduce the force.
And in part that is why MAXIMAL weights are not as good as 75-85% weights. You tend to lower/and reverse maximal weights slower so you are not beating the inhibitory reflexes. With lesser, faster weights, you get up to 360 pounds of force before the contraction gets inhibited.
And it brings up another issue. Maximal weights tend to move faster (therefore higher force) for people who have done or are doing fast/ballistic work. For people who’s tendons have adapted and thickened, heavier weights are going to be able to produce more load even at slower reversals.
So really the degree to which someone should train fast or plyometrically or lighter versus heavier is probably very individualsized, depending on the relative difference between the force they can produce with a stretch reflex, compared to a slower reversal, or in another manner of speaking, if your tendons are thickened to match your muscle strength, then heavier training is going to be best. If your muscles exceed your tendons then you need to train the tendons with lighter faster reps.
If your max reps are slow, OR if you can do fairly high reps with a given percentage (say more than 7 at 80%, more than 3 at 90% with about a 3 second per rep natural tempo) then your tendons probably need lighter faster work. If your max reps are fast (less than 3 seconds) or you do less than 7 at 80% or can’t triple 90% tnen maximal weights are probably striking a good balance between muscle and tendon. 3 seconds would be for a full range bench press. Maybe 4 for a squat, and less for a partial like a board press.