Final answer:
The relationship between intensity, activity, and pulse rate is that as physical activity increases, the body's demand for oxygen and nutrients goes up, which causes an increase in heart rate and pulse strength, leading to a higher cardiac output. The pulse rate is a crucial indicator of physical activity level and cardiovascular health. Energy expenditure during exercise is related to the activity's power level and duration.
Step-by-step explanation:
The relationship between intensity, activity, and pulse rate is a fundamental concept in understanding how the body responds to physical exertion. During physical activity, the body demands more oxygen and nutrients, which causes an increase in heart rate and subsequently, the intensity of the pulse. Both the frequency (pulse rate) and the strength (pulse strength) of the heart's contractions increase to pump more blood, enhancing cardiac output. The stronger and more frequent contractions of the ventricles ensure that blood is efficiently circulated to meet the body's elevated demands. As a result, the pulse rate serves as an essential indicator for assessing the level of physical activity and the body's response to it.
For example, moderate-intensity and vigorous-intensity exercises, as defined by the 2018 Physical Activity Guidelines, are associated with specific ranges of heart rate increase, reflecting the body’s energy expenditure (E = Pt), where 'E' stands for energy, 'P' is power level, and 't' is time. The energy required for and used during an activity is directly related to the power level and the duration of that activity. A higher intensity workout will lead to a higher pulse rate and greater cardiac output. Monitoring pulse rate can thus provide valuable health information, flagging potential cardiovascular concerns if the rate or strength of the pulse deviates from expected patterns during specific activities.