Most high school fields have dismal lighting--it's often strongest in the middle of the field,and weaker at the end zones. THe lighting might also be significantly stronger on one side of the field if the lights are only shining from one side...don;t be surprised if the coffin corners are pretty dim, even a stop or two stops dimmer than the other side's coffin corners!
At F/2.8 at 3200 E.I. (that's exposure index, not the same as ISO,but close)
expect shutter speeds of 1/125 to 1/160 to as high as 1/250 or 1/320--if you are lucky and the lights are new and strong and well-balanced and well-aimed.
It's possible you *might* get a shutter speed as high as 1/400 second at f/2.8 at EI 3200 on a well-lighted high school field, or if the kids play at a junior college or even an NCAA school's stadium.