After arriving on the alien planet, Ji Xinghe's height returned to one meter ninety-three, and he felt a sense of powerfulness he had not possessed for a long time. This was due in part to the special environment of the alien planet and partly because his martial arts had improved further.
But this was just a feeling of being back to his powerful self, not something unprecedented.
The true enhancement in his skills came with real decline in his physique. For example, the ten-kilometer run during the recruitment could have taken less than thirty-five minutes for him in his youth, and he would not have sweated so much during the run. A 42.195-kilometer marathon would not be a difficult feat for his young self.
Here lies the reason why martial arts skills decline with age - skills do not represent everything. Instead, the differences in combat awareness, experience, and physical strength could make up for the gap in martial arts skills.