Clara’s metabolism will remain elevated above resting levels for some time after the race because:
a. the body is metabolizing lactic acid formed during the activity.
b. an elevated heart rate requires additional oxygen.
c. epinephrine released during the run still has an effect.
d. tissues that were damaged are being repaired e. all of these
The correct answer and explanation is:
The correct answer is e. all of these.
After an intense physical activity such as running, the body experiences what is known as “exercise post-oxygen consumption” (EPOC), or “afterburn.” This phenomenon refers to the period of increased metabolic rate following exercise. Several factors contribute to this elevated metabolism, as listed in the options:
- Metabolizing lactic acid: During intense physical activities, muscles may switch to anaerobic respiration due to insufficient oxygen, leading to the production of lactic acid. After the exercise, the body needs to clear this lactic acid, which is converted back to pyruvate and eventually to glucose in the liver. This process requires energy, hence increasing metabolic activity.
- Elevated heart rate requiring additional oxygen: The heart rate remains elevated post-exercise to help the body return to its normal state. The heart must pump more blood to replenish oxygen levels in muscles and tissues that were depleted during physical exertion. This extra oxygen uptake accelerates metabolism as the body works to restore balance.
- Epinephrine released during the run: Epinephrine, also known as adrenaline, is a hormone released in response to physical stress. It increases heart rate, blood pressure, and energy availability during exercise. Even after the race, the effects of epinephrine persist, keeping metabolism elevated as the body is still in a heightened state of readiness and recovery.
- Repair of damaged tissues: Exercise, especially intense or prolonged activity, may cause microscopic damage to muscle fibers. Repairing this damage requires energy and nutrients, thus contributing to the continued increase in metabolic activity. This repair process is also facilitated by the elevated metabolic state following exercise.
Thus, all of these factors work together to keep metabolism elevated post-exercise, making e. all of these the correct answer.