Aperture vs ISO for action shots

Stopping down makes the aperture smaller which lets inless light.  A lens is usually sharpest stopped down two to there stops from it's widest aperture.

Asothers have said, the larger the aperture the smaller the depth of field.

Iso in the digital world is an analog form of post processing applied after exposure but before the conversion to digital. It doesn't makes the sensor more sensitive to light.