Describe the cause and mechanism of anticipatory rise in heart-rate and the effect it has on a marathon runner who is waiting on the start line for their race to start

The anticipatory rise in heart rate is caused by the activation of the sympathetic nervous system in response to the anticipation of physical activity or stress. This mechanism is commonly known as the "fight or flight" response.

When a marathon runner is waiting on the start line for their race to start, their body prepares for the upcoming physical exertion. The brain sends signals to the adrenal glands, which release adrenaline and noradrenaline into the bloodstream. These hormones act on the heart and blood vessels, leading to an increase in heart rate and blood pressure.

The rise in heart rate serves several purposes for the marathon runner. Firstly, it helps to increase blood flow to the muscles, providing them with oxygen and nutrients needed for optimal performance. Secondly, it helps to mobilize energy stores by increasing the delivery of glucose and fatty acids to the muscles. This can enhance endurance and fuel utilization during the race.

Additionally, the anticipatory rise in heart rate also helps to improve mental alertness and focus. It prepares the body for the physical demands of the race and enhances the runner's overall readiness.

However, it is important to note that prolonged or excessive anticipatory rise in heart rate can lead to increased anxiety and stress, which may negatively impact performance. Therefore, it is crucial for marathon runners to manage their pre-race nerves and find strategies to stay calm and focused.

In summary, the anticipatory rise in heart rate in a marathon runner waiting on the start line is a physiological response triggered by the activation of the sympathetic nervous system. It helps to prepare the body for the upcoming physical exertion by increasing blood flow, mobilizing energy stores, and enhancing mental alertness.