There is so much broscience in exercise that it is refreshing to find something based on whatever evidence there might be. Here is such an article, that busts several myths about exercise. (Their previous article, here, has some additional information.) There is yet another article that shows that doing high intensity weightlifting improves cardiovascular fitness. Thanks to CaveManDoctor for the most recent link.
First, to build muscle, you must train to high intensity. “Momentary muscle failure” (as unpleasant as that may sound) is the optimum. It’s best to maintain tension until the muscle fails rather than doing Lift, Relax, Lift, Relax.
Second, they “weigh in” to the classic “free weights” vs “machines” and say that…both are fine. (Machines, properly adjusted, might be safer.) It also doesn’t seem to matter if you do eccentric or isometric or regular reps, and it also doesn’t seem to matter if you do full range of motion. Single sets to failure are all you need. It’s OK to just do this once a week, and up to 3 weeks off is also OK from time to time. (That matches my personal experience.)
One area that PaleoPathologist is very interested in is safety and no injuries. He tried a Stupid Weight Trick last year, a Steinborn Lift with no training, and had trouble with his spear throwing shoulder for several months. With slow controlled, Nautilus machine movements PaleoPathologist can now do more than his bodyweight on a lat pulldown and hold it for 2 minutes. Owee. Next time I have to pull up on a tree branch to escape a lumbering mastodon I’ll be ready.
I will also add that it’s tough to get yourself to momentary muscle failure. A good trainer who knows how to do this really helps. I’ve done 200 yard breaststroke races to failure/vomiting and weights to failure demands a lot of concentration. Your body does not like to go to full failure short term, but in the long run the results are terrific.