The last few months I've gotten serious about training on the bike and I've noticed that now my joints below the waist crack like none other. I'm 17 and in very good health. Now when I stand up my knees, hips, feet, and ankles all crack and pop very loudly. Sometimes I'm sitting in class and just shift my weight and my hips pop loudly. It's not really painful, but it's just an abrupt change and it concerned me.

I've always been very active athletically- football and lacrosse through eighth grade, teeball, baseball, soccer, and basketball interspersed in my younger days, and varsity cross country, wrestling, and a fair amount of heavy lifting all through high school and never through all of that have I had this amount of popping and cracking in my legs.

It's uncomfortable when my hips crack, but the rest of it isn't really painful or hurting me. This may seem like a stupid question, but I was just concerned and wanted to see if anyone had any thoughts on this.
Is it a sign of anything bad going on? Is it unhealthy or bad in anyway? Thanks a lot.