So by now it's really no secret I'm a huge fan of cross-training. I've been cross training since I was swimming. We would run, complete circuits, and just try different things. On my college swim team we would have yoga twice a week (which I absolutely loved!).
Runner's World had an article about the Eight Benefits of Cross-Training. Reading through them I had to agree with all of them and have heard each reason (all except #8 because I'm not there in life yet) from either a coach or a trainer or a physical therapist.
One reason I really like cross-training because of it means I'm always doing something different. I'll have my run days, and then maybe I'll get on a bike or walk up hill for a while. Then there's weights which add a whole new category of variation. It's hard to get bored with cross training, which is usually my biggest problem with training (ironic since I used to swim 1000s and 1000s of yards straight when I was a distance swimmer... and that's the definition of boring). When it comes to weights I tend to focus on body areas; arms one day, then abs, maybe quads, and I mix it up.
Another great thing about cross-training is that one muscle group might be sore, but with cross-training you can focus on a region that's ready to go while the sore area gets some rest. Yes, it'll probably still hurt more than when you're totally rested, but not as bad as torturing that sore area.
My final reason for loving cross-training is the strength training you get from it. Running is great cardio work, but not so great for strengthening muscles. Due to some knee issues I used to have a problem doing squats, but when I tried to use that excuse (yes, it was an excuse) my physical therapist pointed out "You can't run a half marathon if you can't do a squat". So guess what... I started doing squats. Now squats and lunges are in my circuits in one form or another. The increase in strength has really started to make a difference in my running as well. My quads don't get as nearly as tight nor as soon in my races so I'm extremely thankful for that.
Cross-training is like my not-so-secret training weapon. I love it and it's an essential part of my training, no matter what I'm training for. I'm always looking for ways to mix up my cross training some more and who knows what I might find in the future (zumba? kick boxing? pilates?).