4x1600m with 90 sec recovery
McGee says this test is for the more advanced or “tougher types” and can be used to give precise 5K shape. Run 4x1600m, jogging 90 seconds after each interval at your best effort with even pacing.
Apply it: Your average pace for the whole 6400m is a good indicator of your current 5K ability, and can also be a lesson in pacing. Did you start out too hard and fade by the end? Is there a big time difference between your first and last 1600? Aim for even splits, like clockwork.