Continuously running clock:
400m. Run @ moderate pace., 2 min rest
400m. Run @ mod/fast pace., 2 min rest
400m. Run @ mod/fast pace, 2 min rest.
400m. Run @ fast pace., 2 min rest.
the ‘mod’ pace should be 5 sec slower than your 1 mile PR pace.
the ‘mod/fast’ should be done at 3 sec slower than your PR pace.
the ‘fast’ interval should be done at your mile PR pace.