I would recommend getting involved in your school or local news paper. I was a sports journalism major in college, and I found it very beneficial to gain experience learning how to report and build stories around local sports and teams in my area. The ability to do research, gain insight, and eventually report out non-biased sports related information is very valuable. Check out your school or community to see if there are open internships that you can help with - ask them specifically if you can help cover sports that are not getting attention, which would help you gain experience, yet allow you to cover sports stories that are not duplicated by other reporters.
When it's all said and done, you're experience in this area will help you further down the road of being a broadcaster based on your ability to write and communicate effectively.
My advice to you is consider what exactly you want to do in sports broadcasting and be realistic. If you want to be that guy on tv, then you better have the personality, look, attire, speaking skills, presence to do the job. Consider that these jobs are limited. So get a degree that's broad in scope. Such as marketing, journalism, or public relations. These will also support you if you 20 years from now as careers change. Especially for on air talent. Take a minor in production related courses in learning the craft of photography, videography, editing, tv production, etc. always remember the technology is always changing. A sports anchor/reporter almost always starts out shooting and editing his own material. Many times one man banding. 6 - 20 minutes of content daily.
My advice to you is this because one very talented anchor I used to work with now does PR for the state I live in. He worked in some decent sized markets but in later on found stability elsewhere. So not saying to persue your dreams, just be prepared, realistic, and honest about yourself and your goals.
There are many schools with journalism degrees that have an emphasis or courses on sports journalism. Oklahoma State is the first school in the country to have a Sports Media major, which focuses solely on sports in the journalism/broadcasting field and first sports media program of its kind. They even have a master's program for this field, too. Take a look here and feel free to reach out with any other questions. http://sportsmedia.okstate.edu/