How is the heart rate of a person running different from their resting why this change necessary?

How is the heart rate of a person running different from their resting heart rate?

When a person is running, their heart rate increases significantly compared to their resting heart rate. This is because the body requires more oxygen and nutrients to fuel the muscles during exercise, and the heart pumps faster to deliver this increased demand. Several physiological changes contribute to this elevation in heart rate:

1. Increased Oxygen Demand: During running, the muscles need more oxygen to produce energy. The heart responds by pumping faster to circulate oxygenated blood throughout the body, ensuring an adequate supply to the working muscles.

2. Sympathetic Nervous System Activation: The sympathetic nervous system, responsible for the body's "fight or flight" response, becomes activated during exercise. This activation stimulates the heart to beat faster and increases the force of contractions, leading to a higher heart rate.

3. Stroke Volume: The stroke volume, or the amount of blood pumped out by the heart with each beat, may increase slightly during running. However, the main factor contributing to the increased cardiac output (the amount of blood pumped per minute) is the faster heart rate.

4. Heart Rate Variability: The heart rate variability (HRV), which refers to the variation in time between heartbeats, may decrease during running. This is because the heart rate becomes more regular to meet the steady demands of exercise.

Why is this change necessary?

The increase in heart rate during running is essential to meet the body's increased oxygen and nutrient requirements. This adaptation ensures that the muscles receive the necessary fuel to sustain the physical activity. Without this increase in heart rate, the body would not be able to perform at the same intensity or duration during exercise.

Additionally, the cardiovascular system adapts to regular exercise over time. With consistent training, the heart becomes more efficient at pumping blood, and the resting heart rate may decrease. This adaptation reflects the heart's improved ability to circulate blood effectively, even at rest.

Therefore, the change in heart rate from resting to running is a necessary physiological response to the demands of exercise and is crucial for maintaining optimal performance and cardiovascular health.