Here is a great alternative method to use when training with a power twister. Instead of doing standard sets and repetitions, for example 3 sets of 10 repetitions, try holding the peak contraction point of the exercise for a certain amount of time, or even to the point of momentary muscular failure. For example, if performing the standard twister exercise with the bar in front and twisted into an inverted "U", hold the maximum tension point while watching a clock, or better yet, timing yourself with a metronome. There are different levels of twisters on the market, from light to medium to heavy tension. You can begin with shorter duration holds on a light or medium-tension twister, say 20 or 30 seconds and, over time, gradually work up to holds of 5 minutes non-stop then move on to a more challenging twister and begin with shorter duration holds, increasing time once again. Give it a try!