Maybe they say something likeInteresting, thanks for clarifying. Although I'd say that 7ata yoom can mean 'even when' in the Gulf seeing as yoom is used to mean 'when' as well as 'day.' I supose like 3indama in MSA.
Can you switch the sentence round and say:
أمارس الرياضة مع أنّي كبير في السّن