If you are a student athlete, you do two things: Study & Sports. If you are just a normal student, you do one thing: Study. Athletic students have to somehow organize the time to fit both time to study and to play sports. They also have games to play against others, which result making their time for studying shorter than normal students. Since student athlete have to do more things than studying unlike others, I do think their life is harder.
You have more things to do and you must be more organized. Student athletes are typically told that student comes before athlete which means you must put education before being an athlete. Education is very important you and you must have it to do almost anything. Having practice last night is usually not a good enough excuse for the teacher because playing sports is a privilege and if you chose to go to practice last night with a load of home work. That is your decision and you own it. You must be able to be a decent member in the class and also be able to play your best on the court, rink, field, where ever.
I'm an AIG student taking high school courses in middle school, so you could technically say I have heavy workload too. It's mostly about being able to handle the weight, once you get used to it it's nothing hard. If you're bad at handling your work, school will always be hard for you.