In conventional crunches, you are able apply resistance to your abdominal muscles for only 50 percent of your potential range of motion. And crunches performed in the ill-conceived ab machines currently on the market usually require naught but static contraction from your abs while your hip flexors move the resistance. Compare that to the 100 percent greater range of motion afforded by SportStrength patented designs. For each crunch you perform, you do twice the work. That means twice the effect.
Partial movements have their place in sports training.
However, it's safe to say that full range movements are generally more productive in improving strength and muscle mass. This is true for the abdominals as with any other muscle. Yet, incredibly, full range ab work has been virtually overlooked by training experts over the years. That s why Dr. Hatfield patented the concept of prestretching the abs before exercising them. But there are some other good reasons why the patented curved back design is so effective in ab development.