Science Buddies: "Ask an Expert"

My science fair project is about how the heart rate increases with exercise. I am having subjects do multiple exercises (all from resting heart rate) and having them record their heart rate after 30 seconds, 60 seconds and 90 seconds. My questions are:

1) Why would a person's heart rate go down after more exercise (for example, 110bpm after 30 seconds, 100bpm after 60 seconds)?

2) Will hot or cold weather effect my heart rate at all during exercise?

3) If I took breaks in between would my heart rate stay the same?

4) Was it alright to have different aged people as volunteers?

5) If I was older would my heart rate increase compared to someone younger?

Thanks for your help in answering these questions!

Hey there!

This is a cool experiment. I hope it’s going well for you. As for your questions...

1. The person’s heart rate may be decreasing due to inconsistencies in the exercise. Possibly, the person’s heart rate is dropping when they stop to measure after 30 seconds. Another possibility is that they begin to exercise at a slower pace.

2. Yes, cold weather will spike heart rate because the cold causes arteries and blood vessels to shrink, forcing the heart to work harder

3. Your heart rate will still fluctuate slightly as you stop and start exercising. Think about it like this: if you try to blow up a beach ball with a hole in it, it will inflate as you blow it up but will deflate once you stop blowing. If you blow but take breaks in between, the ball will stay around the same size but will still lose some air during the breaks.

4 and 5. Generally, you should try to keep every variable except the independent variable constant. As you age, your resting heart rate changes, which will lead to some wacky results. However, if the age differences are only a year or so, this shouldn’t be too much of a problem.

Hope this helps! Feel free to ask more questions

Emma