This is a classic movement that's been all but forgotten. I'm bringing them back with a twist that Tom Platz taught me. While visiting him, we did iso-holds, but while in the hold position, Tom actually applied additional pressure, making me "tense" the muscle even more. This is probably the most brutal high-intensity technique I use, pain-wise.
Certain movements such as hack squats, reverse flyes on the pec deck, dumbbell curls, and triceps pushdowns lend themselves well to adding pauses at certain points of the range of motion. The length of the pause can vary – a simple 1-2 second pause at the mid-range point is sufficient, but anything up to a 10-second hold with extra pressure being added works really well, too.
You can also add more than one pause. This works well in lifts with a long range of motion. Some coaches will add 2 or 3 pauses for 3-7 seconds each at different points in the eccentric phase of a chin-up or dip.