I may need installing of occluder device to fix atrial septal defect in my heart (of size about 1cm2). will it limit my future athletic abilities, make me avoid any strenuous or prolonged physical exercises? will i need special care?

The procedure by itself does not have any detrimental effect for your cardiac function in the future and that's the reason why it should be done. Although ASD closure won't effectively reverse the preexisting cardiac condition which has been caused by the ASD but it halts the progression. If your cardiac function is fine now then you should be fine after the procedure. Good luck with the procedure

I'm not aware of any restrictions after the device has been in place for a week or ten days. It's reported that exercise capacity improves significantly if anything. If you have to take anticoagulant therapy for a certain time after the procedure, abstain from contact sports during that time. Further advice & complete instructions should be obtained from the person who performed your procedure.