I'm not going to say what you should or shouldn't do. Each applicant has to make up their own mind what they want to and will participate in. There is no magic list of check boxes that if you complete all the boxes, you automatically receive an appointment. It doesn't work that way.
But I will say that the "AVERAGE" cadet who is currently at the academy, and thus received an appointment, were not the type of applicant who was weak in certain areas. The average cadet had a very extensive resume. It starts with taking the most difficult classes their school offers. AP, IB Program, Honors, etc... Many, especially those who didn't have AP/IB available, took classes at their local community college on their own. The average cadet, WITH these high level classes, had a 3.86 or above GPA. Most of them weren't just the top-10% of their class. Many were in the ACTUAL Top-10 numerically. ACT scores were averaging 29-30. SAT were averaging above 650-675 each test.
Besides this, the overwhelming majority, were also in 1 or usually MORE varsity level sports. I say "Varsity level" because some did non school athletics like STING which is soccer at a higher caliber than high school; martial arts; etc... These individuals were ALSO class officers or officers in 1 or MORE clubs. They had 200+ hours of volunteering. They attended boy/girl state. They also had leadership positions in their athletics. Most of these cadets didn't have JUST sports, or JUST band, or JUST CAP, or JUST JrROTC, or JUST FBLA, etc... Many of these cadets had a plate that was so full, if it was food, you'd PUKE just thinking about it. And I'm not talking about the UBER Student like Hornet and others who kicked butt in high school and also kicked butt at the academy and now are in grad school. I'm talking about the AVERAGE cadet who made it to the academy.
I know one who was in the IB program for all 4 years of high school. Was in the top 3 of his class. Played 2 varsity sports and a summer sports program. Elected to all state and all conference teams. Was a Class Officer. Had more than 300 hrs of volunteer time. Who attended boy's state. Was also in the band. (Try marching a half time show in band, while in a football uniform). Yes, I've seen this. This individual was also involved in 2 other school clubs. They also had their personal life where they were involved with local community theater and church. (And no, I'm not talking about my own son).
Point is; the academies do in fact have "Minimum Standards". But for all intent and purpose, you might as well say that those standards are moot and not even looked at. Why? Because the lowest individual receiving an appointment, is STILL above the minimum standards. The person I just described is NOT the uber ultimate candidate either. I've seen those type of applicants too. Take what I wrote, and add a 4.0 gpa (Unweighted) in the IB program. Add more volunteer hours. Add valedictorian. Add 1 or 2 more clubs or organizations to their resume.
You need to be involved in what you WANT TO BE involved in. There's no special checklist for an appointment. You asked if adding track your senior year would help your application. Well of course it will. Just like adding CAP, Young Dems/Reps, or any other activitiy. Everything adds to your resume and application. But only you can determine how involved and how well rounded you are.
It's not a numbers game. It's an "All Around Quality Game". The academy would rather see you in 3 activities, where you became a leader in each of those activities, than to be involved in 6 activities simply as a participant.
So, evaluate yourself, compared to what everyone else has done. Realize, we don't know who YOUR competition is. We don't know who in your district and state are applying to the academies. Only you know if you've done your "BEST" and "MOST" in everything you've done. There are no magic answers or formulas to anything at the academy. Some, who have wanted the academy their whole life, won't receive an appointment. Some, who just thought about applying for the first time a week ago, will receive an appointment. Some, who wanted it their whole life and DO receive an appointment, WILL QUIT the academy in the first 6 weeks, and definitely many more that first 2 years. Some, who never really thought the military was for them, and they applied and accepted the appointment because of the pseudo-free college education, will find that it's totally what they are into, and they'll stay 20+ years and retire. And for some, all the stars align. it's what they ALWAYS WANTED, they get the appointment, they stay in 20+ years, they get great assignments and advance very high, and they become excellent officers.
best of luck to you. mike....