interesting question. Don't know the answer but my first thought is if it was hard to do that second set after a 10m jog, it probably was stressing/improving some aspect of your fitness that needs work. Guessing maybe some speed/endurance factor. Maybe kick at end of race or something.
guess I will trust JD . . . I think I cooled down too much. ran into a parent of billy's old hs teammates so we walked and chatted a lap.