Explain the reasons for the changing patterns of heart rate during and after submaximal physical activity Pls help

The reason for many of the immediate physiological responses to training is the increased amount of carbon dioxide produced by the working muscles, stimulating an increase in heart rate, ventilation, stroke volume and cardiac output.

answer: our bodies are made up of mostly water, we rely on it to regulate our body funtions.

answer; i believe the correct answer is (secondary prevention);