An experiment was conducted to study the effect of a psychological stressor on heart rate. The heart rates of 10 university students were measured under three conditions: at rest, 1 minute before delivering an impromptu speech to a large audience (in anticipation of speaking), and immediately after completing the 3-minute speech. The data collected is shown in the table below:
| Student | Heart rate at rest (bpm) | Heart rate just before speaking (bpm) | Heart rate after speaking (bpm) |
|---|---|---|---|
| Arthur | 72 | 81 | 112 |
| Beatrice | 68 | 76 | 105 |
| Callum | 75 | 83 | 115 |
| Diana | 80 | 90 | 122 |
| Ethan | 64 | 73 | 98 |
| Fiona | 71 | 48 | 106 |
| George | 78 | 88 | 118 |
| Hannah | 69 | 79 | 102 |
| Ian | 73 | 82 | 112 |
| Julia | 70 | 78 | 110 |
Calculate the average (mean) heart rate for the students after speaking. Show your working.
Identify the student who has an anomalous result in the data for heart rate just before speaking.
Suggest why most students' heart rate just before speaking is higher than their resting heart rate.
State two variables that must be controlled in this experiment.
During long-term aerobic training, the muscular walls of the left ventricle undergo hypertrophy (thickening and strengthening). Explain how this physiological adaptation leads to a lower resting heart rate in athletes while maintaining a constant resting cardiac output.
