Accomodating resistance exercise machines
Free weight resistance equipment, such as barbells and dumbbells, provide the same load regardless of the position of the weight or the phase of the exercise.For example, the weight stays constant during both the pushing and lowering phase of a bench press.The bar is lightest when your leverage is at its weakest, and the bar gradually increases in weight as leverage improves. You are getting ready to bench with 200 pounds on the bar. As you bring the weight down to your chest, the bar gets lighter because more of the chains are lying on the ground.So when the bar is at your chest, you bring the weight down to the 200 pounds that you started with.
So instead of benching with high weight and slow velocity (maximal strength), or low weight with fast velocity (speed), you can work in the middle of the graph and accelerate the bar in both the lowering and raising phases of the movement.Constant, as the name implies, means that the weight load on the muscle stays the same throughout the exercise.