If I take Lacrosse senior year, will it be impressive to colleges, even though I’ve only played for 1 year?
It won’t be particularly impressive since at the time of applying you’ll have just a few months experience. Colleges are well aware of people deciding to take on new ECs just as college apps roll around.
If you like doing lacrosse then by all means play, but don’t do so under the impression it will significantly boost your app.
You should play if you want to play and have time to play. Don’t worry about what the college thinks. It will just be another EC to them since you only played for a year.
I wouldn’t worry about how it looks to college- if you want to play, you should play. But don’t think it will give you a boost in college admissions, since you’ve only had a short time on the team.
Play for fun and for physical fitness. Can’t imagine that it would alter admissions decisions.