agree with the previous posts, there is a big difference between training the techniques and even sparring in the club to competing, which increases the risk of injury substantially. Martial arts are contact sports and have a level of risk associated with them and MMA is a combination of all the arts you refer to in your post. Karate and Taekwondo are some of the foundations for the striking elements and have been used by great MMA fighters such as Dan Hardy and Leoto Machida to name a few. Many people train MMA for fitness alone and normally by people who are bored of gym work due to the complex, varied and technical competencies it offers.