A term newborn delivered vaginally after an uncomplicated pregnancy is assessed at 1 minute of life. The infant has a heart rate of 110 bpm, is cyanotic centrally with pink extremities, demonstrates active flexion of all limbs, grimaces in response to suctioning, and has irregular respiratory efforts with weak cry. At 5 minutes, the same parameters are reassessed and the infant now has a heart rate of 140 bpm, is completely pink, has vigorous cry, and demonstrates good muscle tone with active movement. Which of the following best explains the improvement in the 5-minute APGAR score compared to the 1-minute score, and what is the clinical significance of this pattern?