The simple answer to this is no!
No matter what your fitness level is, lessons in Karate and Kobudo will improve on it. As a beginner you will work at your own pace thereby increasing your fitness. This is done by the warm-up and stretching exercises at the beginning of the lesson. Thereby getting your body ready to carry on with the lesson. So by training regularly improvement will be seen in strength, flexibility and cardiovascular system.
A lot of people say “but I’m not fit enough to do karate” or “I’m too old to start now”. Well the answer to these questions are, firstly you don’t need to be fit to start as you start to get fit, secondly Karate and Kobudo are life long activities, and not just for the young. I have had students in their 60’s start, and now have one in his 70’s. No he can’t kick to the head, but he can kick well to the stomach and around the legs, he can now defend himself very well, which is what our Martial Arts are about.