Should I include that I only played 1 year of a varsity sport on my application?

I played varsity tennis for 4 years but I only played varsity volleyball 1 year because of injuries that would always reoccur. Should I include it in my application? And is there a spot on the common app and the UC applications to explain why I only did one year?

I would not include it and usually colleges do not care why you stop doing something. Of course there are exceptions. For example if you played a sport intensely for several years and that took all your time but quit senior year because of an injury that might be a case they ll want to know. Also, if doing something shortly ended up being connected to something else of importance then it might be worth including it so an adcom sees the progression. For example if you played volleyball for a year and then you had to stop but however you kept volunteering all 4 years to the community volleyball camp you might want to include because it is kind of unusual to volunteer in a sport that you never played. As a rule of thumb only include things that connect to who you are and make up your “story”. People try activities all the time and then stop because of conflict. That’s not important to colleges unless the conflict is fundamental to the student’s core story.

Honestly it probably won’t make a difference one way or the other. If you do include volleyball I woldn’t bother to explain why you dropped it – it is normal for HS students to switch activities. If you have numerous other activities that you were involved in at a deeper level, I’d consider leaving it out (or at least put volleyball on the bottom of the list).

Hm I see, what if I recieved an award such as mvp?

^^then it may be worth including, but other poster’s advice still applies. Put the ECs in order of meaning to you