Let's say I use something similar to the exercise bike shown below. When I used to do track, my friends told me while exercising on this machine, to keep a straight back (maybe even a little leaned back), instead of being hunched over (resting your arms/hands on the arm bars). There reason behind this was that staying straight up allows better work on the quads.
Is this statement true at all? I've been using this technique and I find it irritating because I end up sliding forward due to the position/angle of the seat.