Explain how exercise intensity affects immediate heart rate response during physical activity. (5 marks)
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- Heart rate increases in direct proportion to exercise intensity to meet the increased demand for oxygen in working muscles.
- Low-intensity exercise (40-50% of maximum)
- Heart rate increases moderately from resting levels as the body can easily meet oxygen demands aerobically.
- Moderate intensities (60-70% of maximum)
- Heart rate increases more significantly as the cardiovascular system works harder to deliver oxygen to working muscles.
- High-intensity exercise (80-90% of maximum)
- Heart rate approaches maximal levels as the body attempts to maintain adequate oxygen delivery despite increasing oxygen deficit.
- The sympathetic nervous system releases adrenaline during intense exercise, further stimulating heart rate increase.
- These immediate heart rate responses enable the body to adjust cardiac output according to the metabolic demands of the exercise being performed.
- For example, a runner performing interval training would experience rapid heart rate increases during sprint portions (potentially reaching 170-190 bpm) and partial recovery during jogging intervals (decreasing to perhaps 120-140 bpm).
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Sample Answer
- Heart rate increases in direct proportion to exercise intensity to meet the increased demand for oxygen in working muscles.
- Low-intensity exercise (40-50% of maximum)
- Heart rate increases moderately from resting levels as the body can easily meet oxygen demands aerobically.
- Moderate intensities (60-70% of maximum)
- Heart rate increases more significantly as the cardiovascular system works harder to deliver oxygen to working muscles.
- High-intensity exercise (80-90% of maximum)
- Heart rate approaches maximal levels as the body attempts to maintain adequate oxygen delivery despite increasing oxygen deficit.
- The sympathetic nervous system releases adrenaline during intense exercise, further stimulating heart rate increase.
- These immediate heart rate responses enable the body to adjust cardiac output according to the metabolic demands of the exercise being performed.
- For example, a runner performing interval training would experience rapid heart rate increases during sprint portions (potentially reaching 170-190 bpm) and partial recovery during jogging intervals (decreasing to perhaps 120-140 bpm).