I would agree with most posters above, especially the summary of @ucbalumnus, with one caveat to all of the “sports matter little” refrain: one distinction between many ECs and sports is the sheer amount of time varsity sports often requires in high school. I myself denigrated sports team participation back in the day, and many of my friends continue to do so, but I have two sons who are multi-sport varsity athletes and I have been staggered by the amount of time and effort it requires just to be on a team.
During football season, for example, which lasts their entire fall trimester, they have practice from 3:00 (when school lets out) until almost 6:00 each night, they have a mandatory early-morning work out a few days a week, and game days require a nearly five- to six-hour commitment with all of the pregame, travel, etc. Adding in a little time for reviewing game film, and it is easily 20 hours/week. Some sports, like basketball, are even worse because of the sheer number of games and many are on weeknights. On top of this, sports will be physically exhausting–my sons come home from practices and games tired, many times bruised and sore, and completely drained. On weeknights, they shower, eat, and then do homework for several hours before bed. I know of basketball and other sport players who are up doing homework at 4:00 am, or staying up late until 2:00 am, because their games had them traveling immediately after school and did not get home until 11:00 pm.
Compare this to being a member or even an officer in Key Club, or an honor society, or quiz bowl. Those are great ECs, sure, but when admission officers evaluate various applicants’ resumes, they will recognize that a varsity sport is far more demanding than most other ECs one-on-one. Of course that recognition will not overcome a big difference in grades and test scores, but if your athlete has a 3.7 and the other is only a “key club, Spanish honor society, and tutor 2 hours/week” with a 3.8, I think the athlete shows more focus, work effort, and (possibly) potential.
My point is simply that it is not fair nor accurate to dismiss sports as “just another EC” because it is not. It is more akin to a serious part-time job than just another EC. Again, that in and of itself plus $.50 will get you a cup of coffee, but it does reflect differently on your resume than some want you to believe.