In my last post, I described the autofocus settings I use for soccer when using my Nikon D700. One of those settings that I use every time I shoot sports is the "AF-ON Only" setting found in the focus custom setting menu (a5). This setting removes the autofocus function from the shutter release button. It requires the use of the AF-ON button highlighted above to activate autofocus. This allows the sports photographer to make the camera autofocus on fast moving subjects well before the shutter release button is ever depressed. It eliminates one step of a three step camera process when only using the shutter release button (autofocus, exposure and shutter firing). I get more in-focus sports photos that are properly exposed when using my thumb on the AF-ON button to autofocus, and my index finger to take the picture.
Try this technique. After some practice, you'll get more in-focus shots (with proper exposure) than using the shutter release button alone.