Originally Posted by
spartanKid
Realistically, cycling has a very short ROM as well. You're never locking your legs out at full extension while pedaling, and you're at most moving your legs ~350 mm in a pedal stroke.
The fast movement is to train explosiveness, likely for the first few pedal strokes of a standing start or the first few pedal strokes in a hard sprint. Doing ballistic movements where you can accelerate the weight and let it fly away from you without using your muscles to slow it down (like when you stand up at the top of a squat, you actually have to slow down the weight), is one of the ways to actually get faster and train speed in the gym that will transfer to the bike.
I think my question may have been misconstrued. I wasn't suggesting that the press ended with a full leg extension -- that wasn't the focus of my question. I was only using a full leg extension to illustrate that the press was starting only 6 inches or less "below" that full extension point. The gist of the question was regarding what type of leg press is this where they are letting their legs drop down only a few inches, and what type of muscles does it activate vs starting the press with the legs bent more.