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
Heart rate be higher due to the improved response time and short duration. While each may have predicted heart rates of 180 (= 220 − age), these two people could have actual HR 20 beats apart (e.g., 170–190). Further, note that individuals of the same age, the same training, in the same sport, on the same team, can have actual HR 60 bpm apart (160–220): the range is extremely broad, and some say "The heart rate is probably the least important variable in comparing athletes." "Heart rate reserve" (HR) is the difference between a person's measured or predicted maximum heart rate and