Adarq.org

Well yeah, obviously, but for the tendon to deform and play it's elastic role, you still need strong calves, like you said, to contract isometrically.

However, for me at least, the biggest problem is still quad isometric strength since that's what prevents knee collapse, and I've always had a problem with that all my life. If I had that I'd be able to use a lot more speed, that's why I was saying that I need to find a way to train my quads to maintain/generate great isometric strength. One way, I think, is depth drops or isometric 1/4 pin squats, but I don't have any squat rack with pins where I train to do it.

TOO FANCY FOR ME!

why on earth would you want to do isometric 1/4th, oh ok, you said pin squats.. ok that's fine.. i didn't see pin there for a second..

sure, 1/4th pin squats would be the way to go.. iso 1/4th HOLDS are way too dangerous.. if anyone is going to do a "hold" they should just do a walkout with pins set real high, that'll be more than enough to cause adaptations.

What are other people's suggestions for developing quad isometric strength?.

high rep rebounding half-tuck jumps (MR half tucks, 25-50 reppers), stiff legged pogos (5-10 reppers), heavy half/quarter squats, sprints, tke's, jumps (single and double leg rvj's), and possibly depth drops but if the other stuff i mentioned is lacking, no need for those.

so ya, i didn't list any actual prolonged isometric exercises, instead everything i listed is miometric/pliometric.

i'm not a big fan of isos, in fact I hate them except for paused lifts.. paused squat/paused lunge would undoubtedly hit the hams/glutes harder than quads, and for the paused squats, that would be the case pretty much regardless of depth unless you really allow the knees to shift forward.

if I were to do isos, the only one I actually like is the "iso extension stim" method, where you iso a 45deg hyper, but that's p-chain dominant.. quad isos really put too much stress on the patella/patella tendon for my liking, it's a prolonged tension that just can lead to way too many pathologies like tendonities etc.. the quads are just way too strong to load up isometrically imo, really heavy isos targeted the quads just place too much stress on the knee.. the patella is sesamoid so, it's much diff than hamstring/glute isos for example... i think that's one of the key problems with them.

so ya, the stuff in bold at the time, that's the stuff i like.

peace

RE: Hip flexors

Go back to the things I said earlier this thread about femoral control.

We know that what happens to the legs during the recovery phase (once the foot comes off the ground) plays no direct role in sprinting (see the infamous Weyand study)

The harder you push against the ground, the faster you go.

BUT....

Having an optimal posture (repositioning your legs correctly) allows you to set up in a way that allows you to more efficiently exert more force when your foot does hit the ground....you get a better wind-up, better leverage, and a greater pre-stretch from the contributing musculature (the muscles that contribute when your foot makes ground contact)

If the hip flexors are weak it's very difficult to get to that posture and people will either shorten their strides up or flail their feet sideways, as the TFL and rectus femoris try to do what the psoas can't. It's easy to see from the back. 
Look at who has naturally strong hip flexor and great femoral control and who doesn't. Femoral control = the muscles in control of the femur from the hip (the hip flexors and glutes) are fully in control of the femur from both sides.

Best strengtheners: Look at the sprinters posture than try to duplicate.  The hip flexors are one of the few muscles that tend to be weak in the shortened range (the very top of a full knee or leg raise) rather than the stretch range.  Here is an exercise to test.  Keep the natural arch and don't lean back.

http://www.youtube.com/watch?v=pxkbqUa28BY

 
 A lot of people won't be able to lift their knee an inch without squirming around all over the place. You should be able to come up several inches.

I recommend doing sets of 8-10 with a 2-3 second hold at top on that exercise. The more you lean forward the harder the exerise is. Use bands for extra resistance. 

Another good exercise is doing the same thing standing up, which also happens to hit the glute.

http://www.youtube.com/watch?v=JAUwgrazCg4  (keep the plant leg straight and don't let the knee bend).

Then maybe look into pike variations:

http://gymnasticbodies.com/index.php?option=com_content&view=article&id=10:developing-the-hanging-leg-lift&catid=2:articles&Itemid=3


Raptor, regarding your knee collapse, that's actually more of a combined eccentric and isometric contraction. I wouldn't get caught up in doing isos just get your quads stronger overall in things you know how to do.  You can't affect one type of strength without affecting them all.