What this shows is that you can get in mad shape just doing calisthenics which is why when people say they cant afford a gym dont have time its not a valid excuse get a pull up bar and do some pushups you lazy bastards
Also fyi I do have a pull up bar I do 5 sets of 10-12 reps once a week I think that is plenty of pullups but I dont know maybe some day I will do more. I also deliberately do them slow