My ds14 is involved with both. He runs year round (XC until November, a few months of winter conditioning, track from Jan-Jun, and then summer conditioning), just made it into a high-level orchestra for next year, taking all honors and his first AP (World History), plays in the jazz band (he's a bassist, so does orchestra and jazz band), and does chess in the winter (he's allowed to miss track one day a week, since chess is an IHSA school sport). That said, he's highly disciplined, super organized, and a very hard worker with the social life of an introvert. Yesterday, he had track from 2:30-5:15, and then stayed for jazz band (after a quick shower at school) til 7:30. Today he will leave track at 4:30 to get a quick shower in at school and make an orchestra concert call time of 5:15, hoping to be home by 8pm. Tomorrow he will head straight to a track meet after school and probably not return to the HS til 9pm - thank goodness it's a Friday. Each day he will pack both his lunch and dinner and eat on the run. I think he is somewhat of an anomaly, even among gifted kids. My older kids couldn't have done it at this age. He needs very, very little downtime, and very little study time. I don't think it's about intelligence - I have an older PG kid who would have collapsed under the load. To me, it's really about how organized your kid is and whether they want to have a social life/free time. He's not on Facebook, doesn't watch TV, and rarely hangs out with friends, all by his choice. His activities are most of his social life. He does miss out on some after-school musical extracurriculars (outside symphonies, pit orchestra for musicals, etc...) but he works hard and is moderately talented. We find that the music teachers are FAR more accommodating than the coaches. We've had a few confrontations, but we're hanging in there and trying to make it all work. Next year with even more AP/honors, and more new material (AlgII/Trig is still a lot of review for him), we may have to give something up, or just settle for not being as competitive. Our 4th has already looked at his brother's schedule and decided that he has no desire to follow in his footsteps!!