Answer:
having sexual intercourse
Sickle cell trait is apparently an adaptation for the prevention of Malaria. Sickle cell trait is a condition in which the red blood cells are abnormally shaped, if they inherit two faulty copies of the gene for the oxygen-carrying protein hemoglobin. The faulty gene persists because even carrying one copy of it confers some resistance to malaria. As a result, the frequencies of sickle cell carriers are high in malaria endemic areas.
When working out, it's important to not only craft and individualized workout that works best for your body, but to make each workout focus on a specific area of the body, so that each area gets a particular amount of focus.
