H.I.R.T.S. *Speed is a very important element of the entire H.I.R.T.S. trainer. The training focuses mostly on the legs. Sprinting, jumping, squatting, lunging, and some other lower body exercises are the signature exercises of this element of the H.I.R.T.S trainer. Designed mostly for lower body work outs, the H.I.R.T.S. *Speed element is also very useful with upper body exercise when using the strap handles. H.I.R.T.S. *Speed is your cardio training tool with the H.I.R.T.S. trainer.