This is an old-school, chain-driven machine made by the original innovator of gym equipment – Nautilus and its owner Arthur Jones. In a lot of ways these original designs have not been surpassed. Most machines short circuit whenever speed is applied to it. With appropriately heavy weights the lifter can put as much speed and force into the machine as possible. The cam will cause the weight to decelerate as the lifter’s leverages improve. This is accommodating resistance, it is why bands and chains are effective. Jones accomplished accommodating resistances in the 1970s with a cam and a bicycle chain. That’s why this machine is great for building hamstring strength – because you can use speed and strength. Strength is increased when force production goes up. And force is a product of weight x acceleration.