It became so popular Because James F. Fixx wrote a book all about running and its benefits. This really opened the eyes of the public to running and its qualities. this also opened up the world because before he wrote his book running was only for professional athletes. His book began the golden age of running supplying the average man with enough information to go out and run. Ironically he died of a massive heart attack. Look him up, you will find a butt load of information about him every where. hope that helped
There is more books on running from decades ago because there is little more to add to the information that there already is. Running is a definite sport, either you are good or bad. All the research was found back when the books were publish.