The blood and guts era ended due to rules changed that made the tournament fighting softer and karate instructors watering down their training to attract more students. Others thought the tournament rules didnt go far enough and wanted to fight without restarts and use continues kicks and punches. Hence full contact karate (not to be confused with knockdown karate) was born. It later adopted thr name american kickboxing. It's heyday was the 70's to mid 80's but greatly fizzled out due to lack of public interests and the ninja fad dominating at the time.