Saitama from One Punch Man is one of the most popular characters known to almost anyone who reads manga or watches anime. His popularity is due to a multitude of reasons, but people mainly love him for his deadpan dialog delivery in extremely serious situations.
Humor aside, Saitama is also well-known for his strength in the One Punch Man series. He’s so strong that it only takes a single punch to defeat his enemies, hence the show's name. How did the Caped Baldy get so strong that a mere human like him is compared to the likes of Goku from Dragon Ball?
About Saitama and his powers in One Punch Man
So far, Saitama is arguably one of the strongest characters in One Punch Man. The manga has featured some strong characters and none of them seem to be stronger than him. That being said, there are a few characters whose powers haven't been revealed yet and only time will tell if Saitama can finally find an opponent that will get him excited.
When Saitama revealed the source of his powers, his peers thought that he was bluffing. According to Saitama, he became strong due to his rigorous workout routine. It consisted of 100 push-ups, 100 sit-ups, 100 squats and 10 kilometers of running. Saitama pushed himself and worked out everyday for about three years, which also led to hair loss. Apparently this endurance training was the reason for his strength.
Genos found this hard to believe, because a training routine such as this would not yield such results. It is merely an intermediate endurance training, which only increases the cardiovascular endurance and not overall strength. Even Mumen Rider’s daily activity is probably more rigorous than Saitama’s training routine.
The manga seems to have given an explanation but it is vague. In chapter 88, it is explained that Saitama is different from everyone else since he has been able to break his “limiter." This “limiter” is what restricts human beings’ growth in terms of power. But Saitama supposedly broke his "limiter" through hard work alone. However, the manga doesn’t elaborate further on this explanation.
That being said, fans need to understand that One Punch Man was deliberately written this way, since it’s a gag anime. The charm of this series is that logic cannot be applied to most aspects of this show, especially when it comes to power scaling. Therefore, it is difficult to deduce the reason for Saitama's strength when looked at from a logical stand point.