#2 is correct for what you want to say, but both are grammatically correct. They just mean different things.
When you use a participle clause in this way, you delay revealing the subject until the end of the sentence. The subject of the participle is not necessarily the subject of the main sentence. Consider the following example:
Exploring the attic, Mary found her grandmother's old diary.
Exploring the attic, Mary's grandmother found her old diary.
As in any language, pronouns only make sense when you've already connected them to the related noun. When using participle clauses it's fine to use a pronoun as long as you understand the meaning is ambiguous until you connect it in the main sentence:
Reading her book while strolling through the park, the girl accidentally walked into the man who would change her life.
Since "her" is ambiguous, it could also refer to the author of the book:
Reading her book while strolling through the park, out of blue John accidentally walked into the writer.
This kind of thing isn't common, but it's possible.
With your two examples, #1 suggests the subject (he) is not "the athlete", while #2 implies that they are the same person.