The idea behind X-Force is simple. By tilting the weight stack 45 degrees on the positive motion, we’ve been able to supply a 40% heavier negative stroke. The training experience is the same as with a conventional machine, with smooth movements. 
The result is a deeper inroad on each repetition and more efficient training. This also means time better spent for the user as well as the gym. Since negative training puts more load on the muscles, additional recovery time off is needed between training sessions. The user ultimately spends less time training, leaving the machines open for even more users at the gym.