What is the best major to do in a STEM career while being a student athlete in college?

For someone like you I would suggest doing something you are really interested in. Biology translates really well into medical school. Other majors that would also translate well are Biochem, Chemistry, Neuro Science, and other biology derivatives. But understand you don't have to do science to get into Medical school. Science makes the transition into med school smoother but it doesn't advantage you over someone who didn't study a hard science. Study what you are interested in and what you will do well in. Med school has required courses. Make sure you perform well in those required courses. Aim for a high 3.something GPA in your science courses. If you know you will need help with science seek out help like tutors or study groups.

Another important aspect of being a student athlete studying science is knowing how much course work is too much. Since athletics requires so much of your time and focus I would recommend a 5 year graduation plan if you are going to focus on athletics(since it might be a scholarship provider). If you plan to do athletics more passively (either with or without scholarship) then you can stick to a 3-4 year plan. You have to be strategic about all your classes when you are a student athlete that wants to do medicine. You don't want to do too many classes at once. You want to have enough time everyday to study for hard classes. All of this will help you to maintain high grades. You want a schedule that isn't overwhelming. With such a busy schedule you will have to strategize with you academic and premed advisors to make you are comfortable with your work load, on schedule for a timely graduation, and taking the necessary courses to graduate and qualify for med school. And you have to plan for MCAT study and test taking. These are things to think about.