T Nation

Concentric Acceleration


#1

I had an interesting observation while I was working out. It may not be new to you guys at all though.

I found that if you lift the weight very quickly, the weight gets light. On the same note, if the weight goes up a slowly, the muscle seems to be more tense.

In the cable machine in our gym, you can either set use the a light setting or a heavy setting wherein you lift half the weight with twice the distance and speed of the light setting, in effect yielding the same tension (similar to gear ratios). However, even if I set the weights at their equivalents, they feel very different. It seems to me that you can use momentum in the heavy setting to assist you in the lift whereas momentum is harder to get in the lighter setting.

I'm thinking that it has something to do with gravitiational acceleration. If you accelerate the weight faster than gravity does (9.8 m/s/s), momentum takes over and the weight gets lighter. If you accelerate it less, momentum doesn't take over and the weight stays heavy. This could explain why the heavy setting gets more momentum. The weight accelerates faster, allowing momentum to take over.

Hence, if one wants constant tension in a muscle, one has to accelerate the weight more slowly than gravity does. I guess that means lifting weights more slowly can stress muscles more than when lifting weights as fast as possible because of the constant tension, although it doesn't mean that you'll get stronger. Maybe it's good from a hypertrophy standpoint. Heck, it sounds like Mike Mentzer was onto something.

I guess that means I'll be using the light setting each time I use the cable machine so that I can lift as fast as I can without momentum taking over.

What do you guys think about this?


#2

Just let the negative take care of muscle damage, and let the concentric stimulate the CNS seems to be the best way to train for me personally. You could also try throwing in some long constant tension sets on isolation exercises (one of the 3 methods that CT has been posting about recently) towards the end of your workout, it hasn't done anything for my strenght gains but I have seen a noticable improvement in hypertrophy from doing them.

Granted I have a friend who lifts with a slow(er) concentric and he is pretty big and strong for his amount of time training, so I guess everything works as long as you are busting your ass.


#3

If you are looking for increase time under tension just Increase the duration of eccentric phase. Moreover, not only becoming the TUT, but because of the increased protein degradation caused eccentric phase, you'll get greater supercompensation.

Finally, i think slow concentric phases it is better to limit to isolation exercises.


#4

I think you're over analyzing the use of one machine


#5

Depending on your goals, those differences can make a tremendous difference in your success. Check out some articles on speed training on westside-barbell.com and elitefts.com. For strength development, bar acceleration is key. The harder the explosion into the bar, the "easier" it is to overcome the load. For maximum muscle stimulation though, it might not be the best thing.

Good observation though...


#6

You always have to accelerate the weight faster than gravity. Else, it won't move.

Next, you should study physics a bit more. Momentum says that an object will stay in motion (or at rest) unless affected by an outside force. Gravity is an outside force. Momentum doesn't paly a roll in lifting a weight (at least not the momentum of the weight).


#7

Yeah I know what you mean, but I kinda meant "momentum" in an olympic lifting context wherein you propel the weight and it goes flying instead of constant muscular tension lifting the weight. By no means does the momentum lift the weight. It only makes it feel lighter because it keeps the weight going instead of stopping at an instant.


#8

Yeah, you can say I'm bored.


#9

I think the problem with slow eccentrics is that you can do less concentric reps, limiting neural gains. On any rate, I won't be using the cable machine any time soon because I use compound lifts all the time in my current program. Still, it would be interesting if one could add tension simply by changing the heavy setting to the light setting and doubling the weight.


#10

As long as you are accelerating the load, momentum is not taking over. This is especially evident with cables because the implement you are using does not have the potential energy that the stack of weights does and you are not acting directlly on the stack. Anyhow, that's all semantics what�??s really happening when you accelerate a load quickly is you are calling the higher threshold motor units in to move a load lighter than what they are designed for, or have been trained to do.
So if for instance, your max bench is 315 lbs. and you are throwing up 225 lbs. as fast as possible, you are recruiting the some of not all of the muscle fibers suited to lift 315 lbs. because of the speed. Explosive movements call on the body to use maximal force. This is not a bad way to train, but I'd recommend going heavier for explosive movements, you do not want it to be to light.

This is the kind of stuff Waterbury is trying to get through our thick skulls.

For maximum benefit, I'd actually keep the speed up, not so much that you are sloppy or flinging weight around, but as fast as you can in good form. If you are looking for the burn, do more reps. Having slow concentrics or eccentrics is not going to give you much benefit. As the set goes the weight will slow down as muscle fibers fatigue, so don't worry about that part; you'll get your slow reps in.