In short, type 2 fibers are where the growth potential resides, and they respond only to heavy weights Trialix Review, at least 75% of your 1RM (the largest amount of weight you can use to perform a single repetition).
However, it is an excellent means to increase muscular endurance, and therefore, can be very useful in many sports that have nothing to do with hypertrophy (muscle mass gain). However, if the essential thing is size, high repetitions are not a good idea: neither to grow, nor to define.
In weight training, something has withstood the test of time: to grow, you must be strong. Taking that to the extreme Trialix Review, many lifters adopt a heavy lifting approach with low repetitions.