Should I take slow, deep steps or small, fast steps on a stair machine?

One of the benefits of a chain or cable-driven stair machine is the ability to change the stepping motion. You can build more leg strength by taking longer, deeper steps and pushing through each step.  Taking shorter, quicker steps works more to improve speed. This type of training is very useful for working on foot speed for activities that demand quick movements or change of directions. The key with either of these modes of training is to not hold onto the stair machine while exercising. If you are holding on, a lot of your upper-body weight will be supported by the stair machine and you will not get the full strength benefits from the deep step. One of the keys to speed training is core strength and balance, and holding onto the stair machine will limit these effects.  For general fitness, it is best to alternate the two types of training to get the complete benefits of the stair machine.