Canon 5D mark II is a very popular camera amongst photographers of all types. It is by far not the best action sports camera, but I have one of them in my pack too anyways.  I see a lot of people at different sports events using the 5D for action, and there’s nothing wrong with that.There are a few things you have to keep in mind when shooting action with the 5D, and the same principles apply to many other “non professional” or non sports cameras.

 As every 5D mark II owner knows, the slow focus is one of the biggest downfalls of the camera.  Action sports happen really fast, and often you need to rely on the focus of your camera.  I totally avoid tracking subjects with my 5D, and I know there are a lot of people out there who are going to argue with me. But once you compare the focus to any 1D camera, you will forget about tracking subjects with it.From experience I can tell you that the center focus point works way better than the rest.  It is quicker and more reliable, so try to use it every time you can.  The same thing applies to most consumer cameras.The best way to work around the slow focus is to pre-focus.  Just choose a spot where the action is going to happen, focus on a bush or rock on the side of the trail for example and then take the shot as the athlete passes by that spot.  Another thing you can do is choose a side angle where you don't have to track your subject, but rather focus on a spot as he is traveling across the frame.  We have a great article on nailing your focus, that will help you get sharper images…make sure to check it out!
Another big difference between the fast pro bodies and the 5D mark II(or any other consumer camera) is the shutter lag.  Shutter lag is the time it takes for the camera to take the shots after you have pressed the button.  Yes, it doesn’t happen instantly, it is a very short amount of time measured in ms, and for the 5D mk II it's 206ms.  Compare 206ms to the 55ms of the 1D series.  The 1D bodies also have custom functions that shorten the shutter lag even further down to 40ms.  I have tried to capture a specific moment with my 5D when shooting action, and seem to miss it by a tiny bit at times (even when I am sure that I pressed the shutter in the right moment).  Now I always press it earlier and earlier to guarantee I get the shot at the right moment.
Next thing on the list is a viewfinder black out.  This is the time where the viewfinder is black in between frames.  It only matters when you are shooting a sequence of images.  It could be important if you are tracking your subject, because you can lose him in the viewfinder while shooting.  This is not such a big deal for me, but if you are using an older DSLR that has a relevantly high frame rate you can always check it as a reference.Keep in mind these "little" things next time you are shooting, and avoid shots that are not "easy" for you camera.  This could mean the difference between a good or an amazing photo!