Does racewalking look kind of goofy? Yes. Does that mean it isn't a legitimate sport? ABSOLUTELY NOT.
Chen Ding of China won the men's 20k walk this afternoon with a time of 1:18:46. For some perspective on that time, consider that the professional racewalker can usually racewalk faster than the average person can run.
There are only two rules in racewalking. The first is that the runner's back toe cannot leave the ground until the front heel has touched. That means that their feet must keep constant contact. The second rule is that the supporting leg must remain straightened from initial contact until the athelete's body has passed over it. There are judges in racewalking to make sure that all rules are followed. Now, this all makes for a very bizarre-looking technique, but also an extremely effective one.
Because of a shorter stride, the cadence (number of leg revolutions) of a professional racewalker is on par with that of a 400 meter runner. All of this makes for a low-impact but intensely athletic activity.
If you STILL think racewalking is silly, I highly recommend clearing a path in your living room and just trying to walk with the rules listed above. It is not easy, it's fast, and a great low-impact way to stay active.