Can you explain that one? On several occassions, TV interviews, instructional DVDs, gym instructions posted say to do exercises slowly with your muscles tensed all the way and about 4 seconds for the entire cycle (up and down).
The explanation against fast was that the movement would no more than just momentum and could be damaging if you can't control it at the end.
An additional reason I do it slowly is to gauge my form carefully all the way so I don't throw my back out.
Bear in mind my complaint was that there was still a lot of people that thought lifting slow was the 'only way to lift'. So i'm not saying you should lift explosively all the time. Most TV programs and mainstream exercise DVD's give really bad advice though. As a rule of thumb, if anyone ever claims there is one way and one way only to do something, they're probably full of crap... In the exercise world, there aren't many 'black and white' statements, everything depends on something.
In my example, I knew the trainer didn't know the difference between bar speed and lifting speed. For example, you just can't (oops, blanket statement!) lift maximal weights without attempting to lift as fast as possible, however, if it is a maximal weight (>90% 1RM), then even though your TRYING to lift really fast, the bar will move very slow. In other words, I was just being a smart a$$. I know what he was referring to, but he clearly doesn't understand. His statement should of refered to people who don't want to train hard and will use light weights and lift them recklessly - fast, but not control, and not with the actual intention to lift 'explosively'. If he said it in that context, I would have agreed. But trying to criticise me for lifting fast, when I was doing "SPEED deadlifts", was just bizarre.
Also, lifting slow to get used to form is great example of when lifting slow is a good tool, and I do that myself. However, in accordance with my goals (strength), I lift 'explosively', but 'controlled'. You create more force if you lift fast. What do you think creates more force, for example, jogging, or sprinting? It's common sense, really, but that doesn't mean everyone should sprint. It depends on your goals, lot's of people jog for lot's of different (and valid) reasons.
Here's an interesting read on 'lifting fast'
http://www.t-nation.com/article/bodybui ... to_big&cr=