Cardiovascular Fitness Investigation

What's the Point?

By the end of this lesson, you will be able to measure, record, and analyze changes in heart rate and blood pressure before and after exercise to explain how the cardiovascular system maintains homeostasis.

Background

Your cardiovascular system—made up of your heart, blood, and blood vessels—transports oxygen, nutrients, and waste products throughout the body. When you rest, your heart beats at a steady rate to keep blood flowing. When you exercise, your muscles demand more oxygen. The heart responds by beating faster and pumping harder to deliver that oxygen where it’s needed.

Your body’s ability to adjust to activity is called cardiovascular fitness. Measuring how quickly your heart rate increases during exercise, and how quickly it returns to normal afterward, shows how efficiently your cardiovascular system functions.

Key Terms to Know:

Heart Rate is the number of times your heart beats per minute (bpm).

Blood Pressure is the force of blood pushing against your artery walls as your heart pumps.

Pulse Recovery Time is the time it takes for your heart rate to return to resting levels after activity.

In this investigation, you will measure your own heart rate (and optionally your blood pressure) before and after light physical activity.

Materials Needed

Stopwatch, timer, or phone
Notebook or lab sheet
Safe space to walk or perform light exercise (marching in place, jumping jacks, etc.)
Optional: blood pressure cuff or digital monitor

Procedure

Man measuring heart rate after a run

Record your resting heart rate.

Sit quietly for one minute.
Place two fingers on your wrist or neck to find your pulse.
Count beats for 15 seconds and multiply by 4 to find beats per minute (bpm).
Record in your data table.

Exercise for one minute.
Choose an activity such as jogging in place, brisk walking, or jumping jacks.
Immediately after exercise, record your active heart rate.
Recovery period.
Sit down and rest. Record your heart rate again after 1 minute, then after 3 minutes.
This shows how quickly your body returns to normal.
Optional:
If available, measure your blood pressure before and after exercise using a digital cuff or fitness tracker.

Data Table
Condition	Heart Rate (bpm)	Blood Pressure (if available)	Notes / Observations
Resting
Immediately after Exercise
1 Minute After
3 Minutes After

Analysis and Reflection

Answer these questions in your notebook or lab document.

What changes did you notice in your heart rate after exercise?
How quickly did your heart rate return to resting level?
Why does heart rate increase during exercise?
What does your recovery time suggest about your cardiovascular fitness?
How might regular physical activity improve the efficiency of your cardiovascular system?

Extension (Optional)

Compare your results with a classmate or family member. Who had the faster recovery time? What factors might explain the difference—age, fitness level, or type of activity?

Lab Notebook Entry #5
Review the instructions for each of the sections below.

Purpose – State what this investigation was designed to model about cardiovascular response and fitness.
Observations – Write one or two sentences describing what you noticed about your heart rate (and blood pressure, if measured) during the activity.
Analysis – Answer the Analysis and Reflection questions above in complete sentences using scientific reasoning.
Conclusion – Summarize what this experiment taught you about cardiovascular function, exercise response, and homeostasis.

Your cardiovascular system constantly works to maintain balance. When you exercise, your heart and lungs adjust instantly to meet your body’s needs for oxygen and energy. Measuring your pulse and recovery helps you understand how your body maintains homeostasis during physical activity.

Next, you will need to submit your Lab Notebook to include entries #1 - 5. The first three lab entries were already graded at the time of completion. This is a check-in point for the first five entries.

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