Final answer:
During strenuous exercise, a healthy young individual's heart rate can increase to 150 bpm, with a corresponding increase in cardiac output to about 19.5 L/min, or 4-5 times the resting rate. Elite athletes can enhance this further to 7-8 times their resting output. Such strenuous activities result in various physiological changes, including altered heart rates and blood flow.
Step-by-step explanation:
During exercise, the heart rate (HR) can increase significantly. In healthy young individuals, HR may rise to 150 beats per minute (bpm) during strenuous activities.
This increase in HR, coupled with an increase in stroke volume (SV) from 70 to about 130 mL due to stronger contractions, can elevate the cardiac output (CO) to approximately 19.5 liters per minute, which is around 4-5 times the resting rate. Elite cardiovascular athletes are able to push these boundaries even further; they can increase their resting CO by 7-8 times during peak performance.
Moreover, during endurance events like a marathon race, a runner's blood flow can increase up to 10 times the resting rate. Factors such as a decrease in blood viscosity and an increase in the blood pressure difference across the circulatory system play a role in enhancing blood flow during such intense exercise. These changes influence the average radii of the blood vessels.
When relating this to swim exercise, a data table demonstrates that for a student athlete's time to swim 2,000 yards, the heart rate decreases by 1.5 bpm for each additional minute added to the swim time. Therefore, the longer it takes to swim the distance, the less exertion the heart experiences.
In terms of calculating the time per beat when the heart rate is 150 bpm during strenuous exercise, it corresponds to a time of 60 seconds divided by 150 beats, resulting in 0.4 seconds per beat.