because i have a trouble with my knee, i have to switch using elliptical trainer. but later i found out that work out on elliptical trainer for 20 minutes is really way much harder than running 20 minutes. my heartbeats raise so fast during using that machine.
i thought i was going to explode, really.
i want to be able to exercise with elliptical trainer for 30 minutes, or even more. how to do it?
how to avoid soreness?
do i burn more calories using elliptical trainer ?