In addition to the exposure (specifically the Shutter) settings as mentioned above, and continuous shooting mode for rapid fire shots, you need to take control of the autofocus system to ensure that a moving subject is kept in focus. The AF system of the D7000 is designed for sports and action shots, and if set properly can wonderfully track and stay focused on moving subjects. But you have to understand and make proper use of it to get the most out of it.
First I refer you to the article
Using the D7000 Autofocus System :
http://blog.dojoklo.com/2011/05/28/using-the-nikon-d7000-autofocus-system/
The AF system involves 3 parts - the Autofocus Modes, the Autofocus Area Modes, and the AF related Custom Settings to specify exactly how it works in specific circumstances.
Set the AF Mode to AF-C, as mentioned above, for continuous focus on the subject as you half-press the Shutter Button. The camera will keep evaluating focus so that the subject ideally is in focus when you take the shot, even in continuous shooting mode.
Choose the AF Area Mode based on how you wish to work. If you want to follow the subject around with the camera and try to keep it located under the same selected AF point, use Dynamic Area AF Mode. Choose the most precise Dynamic Area that you or the situation can handle.
If you wish to hold the camera relatively still as the subject moves around in the frame and is tracked as it moves among the AF points, use 3D-Tracking.
Either way, you need to manually select which AF point starts to track the subject.
One of the the Custom Settings will tell the camera how long to wait to refocus on another subject if you "lose it" (if it is no longer under your selected AF point).