Hello
You are healthy , doing exercise regularly B P normal , lungs great , pulse great . But question is that then , Why are you having swelling over ankle and legs . Yes this is a cause of concern particularly in a person at the age of 65 years in spite of healthy life. Such swelling may be due these reasons , these includes.
1 Congestive
heart failure , as this is most common cause in this age group So please get in E K G , E CHO and color doppler to rule out CHF ( CONGESTIVE HEART FAILURE ).
2 Hypoproteinaemia as this is also most common cause get in blood for
protein analysis . Also get in urine complete examination.
3 Anemia is another such cause but you mentioned that you are physically very active so we can rule out this .
4
Chronic renal failure . Get in
ultrasound of both kidneys as well as
serum creatinine and blood urea examination.
In my opinion consult a nepherologist and get his opinion as this type of swelling is a cause of concern.
Hope this information will be helpful for you.