A brief tour around youtube at the rep speed of the top bodybuilders tends to lend credence to lift fast to get big a metholodgy given much vent by Waterbury amongst others. I have never really lifted that way, instead I lift much more slowly and controlled maybe thats the reason I aint big LOL. The thing is though I could definately lift more weight for any prescribed rep range by lifting at a faster rep speed instead of grinding out at more of a steady speed so is that why in essence faster rep speed looks to be a better way to train?

The fact that ultimately its because you are shifting more weight? A weight I could lift presently for say six reps at my moderate tempo could be done for two maybe three more reps if I were to increase the speed. To get back to where I was lifting just six reps at my much faster rate of lifting it would be neccesary to increase the weight so I could lift say 300 pounds bench press for six slow reps but 320 for six rapid reps. More weight on the bar = more muscle mass? Or is there something else entirely to the fast rep that there is lacking in the slower rep?

I can't tell you the exact reasons, but i've always known it to be true that lifting "explosively" is better for you. Something about helping recruit the more powerful muscle fibers or what not. I think it may also help your CNS by getting you to fire more fibers at once but don't quote me on that.

Another benefit that you mentioned is you'll be able to use more weight. Being able to use more weight is obviously beneficial for someone looking to get bigger and stronger.

However always remember to lower the weight in a controlled manner. This is for safety reasons and because it has been shown that stressing the fibers on the eccentric portion of the ROM (by lowering the weight in a controlled manner) also helps increase strength. You don't have to take 6 seconds or anything, but don't rush it.

Well, the key is not to get too bogged down with lifting speed. I do agree with the fast lifting. The great bodybuilders did it, many other people do, and I do it (with great success), so, I think its safe to say there's something to it.

Basically, its simple. Lift fast but under control. The reason you can lift more while lifting fast is due to a number of reasons:

1) More force. The faster you lift, the more motor units, particularly the ones with greatest power (type IIB) get involved. When you purposefully lift slow, their recruitment is minimized.

2) Psychologically easier. Its simply more enjoyable to lift faster. If you know your going to be lifting slowly for most of your lifts in your upcoming workout, you probably wont be too enthused. If however, you know you'll be exploding the weights, giving no regards to "slow and steady". you'll probably be more psyched up, and consequently more productive.

Those are the two biggest reasons. If I think of more, I'll post again.

Does this help?

its not the lifting speed per se but the "intent to accelerate" that forces more muscle fibers into action, assuming that the prime movers in said movement are the intended muscle groups "trying to accelerate".
I personally always lifted as fast as I could when starting out simply because I could add weight to the bar faster since I was using as many muscle fibers as I could in each rep, if that makes any sense.

That doesn;t mean that the bar is necessarily going to be zipping around (except in a power clean for example where actual speed is a factor) since you get to a point where you're grinding out a lift even though you're trying to move it as fast as possible.

I also agree with Waterbury's idea of "stopping each set when you're not using enough muscle fibers" but resting and doing more sets such that the TOTAL number of reps is that same. I don;t follow it of course, but it does make sense.