Practice makes perfect. If you are want to capture moving wildlife, but need some practice, sports is a great way to practice. I have shot mainly soccer and football(some tennis, baseball and track) and it helps to see how your equipment works, especially if you are making a big trip to Africa to shoot wildlife. During an expensive trip is not the time to learn how your equipment works. It is best to learn how it works, get familiar with all the controls and also have a good idea about outcome of an image before you take a trip.
In shooting sports, I use a monopod, because I'm moving up and down the touchline (sideline for those of you unfamiliar with the most watched sport in the world, soccer) and have to be able to jump out of the way of a ball or player headed my direction. I use VR on my Nikon 200-400 and usually zoom out to watch action and zoom in when I see what I want. I always pre shoot some images of players to make sure my exposure is not blowing out highlights. I shoot in A priority and watch my shutter speed to make sure that I have enough speed to capture action sharply. Watch your image count on your card, it's a shame to have 5 images left and start ripping off what should have been 10-20 images and miss the best action because your card is full.
I have gotten some great shots of soccer and football over the years and know that it helps when I am focused on shooting wildlife action. It helps if you have kids that play sports. My oldest son played HS soccer and my middle son plays HS tennis and the youngest is playing HS football (and hopefully soccer in spring). Rob Sheppard, a great friend of mine, has done the same thing with baseball and soccer, his 2 kids sports. He has advanced to college soccer as Sammie now plays in college. You can hone your photography skills while being involved in your child's life. Pretty much a win/win situation. To see some images from my most recent football shoot, go to www.flickr.com/photos/bcphoto3/ .
Get out there and practice and spend some time with your kids..