Have you ever had a non-paddler say something to the effect of "oh, that must be a great arm workout" when they find out you're a kayaker? While that's understandable, its pretty bad when a kayaker says the same. And, we all know many do.
Right now you might be wondering what's wrong with that? If so, then you've come to the right post. Of course kayaking involves the arms, but that is not where the power is generated for a kayaking stroke. The main source of propulsion is driven by the core muscles of the body. The arms should merely transfer that power.
The truth is, proper kayaking technique involves the whole body. So, if you're arms are really sore after paddling, you most certainly are pulling the paddle through the water with your arms rather than allowing your torso rotation to paddle the kayak.