I guess that literature has evidenced certain effects in P300 amplitude during simple oddball tasks across different exercised-populations. Moreover, those studies have examined other features such as latency and area under the curve (AUC). 

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Dear Mohamed Elghoul,

I found some papers which deal with this subject. In the most cases, they analyzed the effects in P300 amplitude. Specifically for your groups (swimmer or karate players, and no-athletes) I found certain difficulty, mainly for that two specific sports. However, look also in the references section of the articles that I sent to you. I believe that they contain information that can enrich your research.    

I hope this helps,

Hi Mohamed,

Not specific to the sports you mentioned, but this paper examined P300 in expert and novice badminton players. Looking through the reference list should give you further papers too 

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