Free weights give you a constant resistance. For example, if you do a bicep curl with 25 pound dumbbells, the resistance is 25 pounds when you start the exercise and 25 pounds when you finish the exercise. It is constant. It does not vary. X3 uses variable resistance training, which effectively lowers the resistance during the lifter’s weakest range of the lift and increases it during the stronger portion. As a result, you put less stress on your joints where you are weaker and more stress at points in the range of motion where you are strongest. With X3’s variable resistance exercises you maximize the force being applied to the muscle, which builds greater muscular activity. Learn more how X3 compares to free weights