This report details a cardiovascular and respiratory experiment conducted on September 28, 2023, to investigate the relationship between physical exertion and physiological responses. The primary objective was to measure changes in heart rate and breathing rate following a standardized exercise protocol and to analyze the data for statistically significant correlations. Understanding these responses is fundamental to sports physiology, public health, and the diagnosis of cardiopulmonary conditions.
The experiment involved ten healthy adult participants, aged 20-25, with no pre-existing cardiovascular or respiratory conditions. Each participant underwent a baseline measurement of resting heart rate and breathing rate. Following this, they engaged in a 10-minute period of moderate-intensity cycling on a stationary ergometer, maintaining a target heart rate of 70-80% of their predicted maximum heart rate (calculated as 220 minus age). Heart rate was monitored continuously using a chest strap heart rate monitor, and breathing rate was assessed by counting breaths per minute visually every two minutes during exercise and for five minutes post-exercise.
During the exercise phase, a clear upward trend was observed in both heart rate and breathing rate. Average resting heart rate across all participants was 72 bpm (SD = 5.2), while the average heart rate during the final two minutes of cycling reached 145 bpm (SD = 11.8). Similarly, resting breathing rate averaged 16 breaths per minute (SD = 2.1), escalating to an average of 32 breaths per minute (SD = 4.5) during peak exertion. Post-exercise, heart rate and breathing rate began a gradual recovery, returning to near baseline levels within the 5-minute observation period. The average heart rate at 5 minutes post-exercise was 98 bpm (SD = 9.5), and breathing rate averaged 22 breaths per minute (SD = 3.1).
Statistical analysis, employing a paired t-test, confirmed a statistically significant difference (p < 0.001) between resting and exercising heart rates, as well as between resting and exercising breathing rates. The correlation coefficient between heart rate and breathing rate during exercise was calculated at r = 0.88, indicating a very strong positive linear relationship. This suggests that as heart rate increases due to physical demand, breathing rate also increases proportionally to meet the body's heightened oxygen requirements.
The results align with established physiological principles. During exercise, skeletal muscles require increased oxygen supply and greater removal of metabolic waste products like carbon dioxide. The cardiovascular system responds by increasing cardiac output, primarily through elevated heart rate and stroke volume, to deliver oxygenated blood more rapidly. Simultaneously, the respiratory system augments ventilation to increase oxygen uptake from the lungs and facilitate the elimination of carbon dioxide. The strong positive correlation observed underscores the close interplay between these two systems in maintaining homeostasis during physical stress. The observed recovery rates also fall within typical parameters for healthy individuals, indicating efficient physiological adaptation.
In conclusion, this experiment successfully demonstrated the acute physiological responses of the cardiovascular and respiratory systems to moderate-intensity exercise. The significant increases in heart rate and breathing rate, coupled with their strong positive correlation, validate known physiological mechanisms. Further research could explore the effects of different exercise intensities, durations, or varying environmental conditions on these responses, or investigate populations with underlying cardiopulmonary conditions.