Basal metabolic rate be elevated in stress, illness, and diabetes. Menopause may also affect metabolism. Heart rate is determined by the medulla oblongata and part of the pons, two organs located inferior to the hypothalamus on the brain stem. Heart rate is important for basal metabolic rate and resting metabolic rate because it drives the blood supply, stimulating the Krebs cycle. During exercise that achieves the anaerobic threshold, it is possible to deliver substrates that are desired for optimal energy utilization. The anaerobic threshold is defined as the energy utilization level of heart rate exertion that occurs without oxygen during a standardized test
The Heart Part 4 fourth installment in Lamar's "The Heart" song series. "The Heart Part 1" was released as a loose track in April 2010, while "Part 2" was featured on Lamar's "Overly Dedicated" mixtape, released later that same year. "Part 3," featuring Ab-Soul and Jay Rock, preceded the release of "good kid, m.A.A.d city" in 2012. He finishes the song with the line, "Y'all got til April the 7th to get y'all shit together", hinting at the release date for his fourth album (the date turned out to be the day pre-orders opened and the release date was announced to be April 14).