If you want to take action photos you must be able to obtain a shutter speed of no less than 1/500 of a second, 1/1000 is better
On the Canon 7D, move your control to the AV setting, select spot focus (spot focus because you are trying to get the athlete in focus, and have a background that is as blurred as possible. Select A1 focus, set the shooting mode to continious to be able to shoot at a faster frame rate vs shooting in the single mode.
If you are shooting indoors you want to select an ISO setting that will allow you to capture the action at the higher shutter speeds. Open you lens to the widest opening, yours is 2.8. Check your ISO settings to make sure your ISO is high enough to stop action @ 1/500.
Where you are allowed to shoot, your position on the will also govern how well you can capture the shots. If you change where you are shooting of course your setting so keep an eye on your shutter speed when you change your location on the floor.

Using spot metering might work, and single point focus is essential.

But it makes no sense to use Aperture Priority when the most important thing is freezing motion. Use Shutter Priority. Set your shutter speed at the lowest speed that will freeze motion sufficiently for your purposes. Let the camera decide the aperture. You might also set Auto ISO and let the camera decide how much dynamic range you'll have (how much noise there will be).

When there is plenty of light to work with, such as outdoor events, it might be even better to use Manual Exposure mode, allowing you to specifically choose the DOF too, while still using Auto ISO to let the camera decide just one parameter.