I figured I might as well give the other side of the story here. This is the reason that this can sometimes be a hard sell. What has been shown on this thread so far is that you can play the game with a high degree of physicality. There is no doubt about that.
However, you can be totally fat, out of shape, lazy and look like you are incapable of any high level performance sport and still be really, REALLY good at table tennis. Here is my example which I believe I also used in the thread that appeared 2 years ago on this same subject:
That video is of Richard DeWitt vs Adam Hugh.
Adam Hugh is one of the top players in the USA. He was one of the guys trying to qualify to play in the Olympics for North America for the 2012 games. He was edged out by Timothy Wang who was the only American male to go to the 2012 games for North America.
Richard DeWitt is not young, he is FAT, he cannot move and he barely moves in this game, he does not use pips, those are smooth rubbers, AND, he is giving Adam a seriously hard time, in spite of all of the advantages Adam has based on his physical fitness level and level of training. Now Richard is actually pretty amazing, he is rare, when he was younger he was not in such bad shape and actually played that physical looping style. He went to Sweden in the 80s or 90s to train for a good part of a year. So he has real training. But, you cannot say there is anything athletic about him and yet is really darn good.
So we need to distinguish, here, the physical fitness aspect that you can have and can get from table tennis if you want to, and the high degree of technical skill that you need in order to be really good, that has nothing to do with physical fitness level.
You can be on crutches or in a wheel chair and play really well. You can be fat and out of shape and play really well. You can in your 70s and 80s and play really well. I have seen all of these things. A pro who was top 10 in the world in his 20s-30s can still be top 50 in his 40s-50s. Most sports, that is not possible.
So while table tennis is a sport, and can be used to develop high levels of physical fitness. We have to acknowledge that someone who is old or handicapped or out of shape, can still play at a very high level. This is because, strength and power are not as important in table tennis as technique and skill. A woman who is not strong can still be competitive with a man who is strong in table tennis. Part of this also has to do with the weight of the ball. Good technique will make that little ball go much more than brute strength with bad technique will. In Tennis, there is no way that a top woman can compete with a man who is at the low end of the top 300. I have a friend who is a college tennis coach and he tells me that the top women would have no chance against his top guys and they are not even in the top 300.
While table tennis is a sport and can potentially have some of the strength and physical fitness requirements of some sports, we need to also recognize its uniqueness and not fall in that trap of insisting it must be as athletic as other sports. What it does require, in my opinion, is more technical skill than almost any other sport. The one exception I can think if is the amount of technical skill required in soccer (real football): combining the high speed of constant running with lateral movements and the footwork to control the ball and deceive your opponents can be pretty amazing.
The technical details I am talking about for table tennis are: tracking and intercepting a ball that has so much side and topspin on it; brush contact and the precision needed for that; footwork--the subtle shifts and adjustments of placement, sometimes moving only 2 or 3 inches to be in the right place for the stroke; the mechanics of the stroke--start slow, accelerate on contact, elbow snap for acceleration; reset (this is really part of the stroke)--you need to be set for the next stroke before the ball gets to your opponent so you can be watching his racket on contact and know where the ball is going as it contacts his racket--seeing the ball that extra fraction of a second earlier is crucial to being able to footwork to where the ball is going so you are in position and have your feet set for the next stroke; creating and varying spin; reading the spin your opponent has put on the ball.
I think that about sums it up. LOL