Okay so after reading about CT's criticism of eccentric muscle contractions and elevating concentric contraction lifting, it got me thinking, and then I found this video.
Olympic weightlifters avoid the concentric by dropping the weight. Isn't that what this fellow is doing with these dynamic pendulum swings?
Since the transfer of force is never perfect, one would still need to exert muscular force to keep the weight moving in an arc. Plus, I wonder if various muscles attached to the humerus would work to keep it in the socket.
When you arc the dumbbell forward, you would be contracting the shoulder flexors concentrically, and when you accelerate it down and behind you, you would be working the shoulder extensors concentrically. Reciprocal inhibition might even help you relax them.
So I'm wondering, even though it seems like a stupid exercise, it seems like something like this would be a way to add concentric volume to a routine without an eccentric component, minimizing soreness in the same way that sled work does.
Perhaps the inferiority with stuff like this is that it's just joint isolation rather than a compound pressing movement. Plus since you work agonist/antagonist pairing (like anterior/posterior deltoid sorta in this case) the muscle gets time to relax. Still, the pressing muscles of a leg get a chance to work in a sled drag when you pick the foot up off the ground and bring it forward to plant it again, even if briefly.
You could do something similar with elbow flexor/extensors, like the arm seen in improperly performing a kickback as in here for example http://www.exrx.net/Kinesiology/Errors.html except you would be doing it with momentum instead of slowly like the guy is.
Another example would be dynamic stretching of the legs by swinging between a front/back raise or an abduction/adduction raise.
Bending to get a prone torso, one might be able to do something like this with the pecs/post delt in terms of transverse flexion/extension.
I guess that since it seems that movements like this would fulfill a concentric-emphasizing protocal (I don't like to call it concentric-only, but it does seem to emphasize it) makes me question whether or not we should be avoiding eccentric movements due to their soreness aspect and less directly affecting acceleration/power generation.
Oh and for chinups, if we have a chinup bar in our doorway, couldn't we use our legs to lower ourselves down, kneel on the floor, and then use our upper body to do the chin up and let go of the bar when we reach the peak contraction at the top (perhaps after an isometric hold as CT advises) and drop onto our feet to catch out weight? I thought of this because when I use the rotating handles on the perfect pull up, my knees always hit the floor at the bottom (have to remove them and just pull using the bar to be able to freehang with hip extension).
Unfortunately something like this doesn't seem like an option with a bodyweight exercise like a pushup unless you want to fall on your chest/head. You might be able to do something similar with a dip though...
This is like the reverse of forced negatives. Like someone might normally use their legs to stand/jump to the top of a chinup or dip and lower down using their arms. In this case, you would use your arms to get to the top and legs to lower down so there's less eccentric arm work.
Even for those of us who do want to include eccentric portions, we could always do those after we finish these concentric-emphasizing versions. That way we still prioritize concentric work while getting the extra muscular damage/soreness (if that's desirable, I'm not sure if it is based on CT's critcisms of it) from doing eccentric after.