Although they both improve your aerobic fitness, running does so to a much greater extent than cycling. I cycle a fair amount, and no matter how much I push in terms of speed, cycling doesn't really get me panting.
On the other hand, running for 40 seconds gets me huffing and puffing like a 70yr old 2-pack/day smoker. Is it just me, or is running much more aerobically intense than cycling? Yes, the post states you burn more calories running, but it appears it also has a dramatically larger aerobic benefit. Or so my experience tells me.
