blood pressure

Blood Pressure and Hot Tubs – The Facts

Hot tubs are always relaxing, but why is it that being in one makes you dizzy after mere minutes? This study can help you discover how hot water affects your blood pressure.

What you need:

• Towel
• Bathtub
• Hot tub
• Stopwatch
• Blood pressure (BP) monitor
• Pencil
• Notebook

What to do:

  1. Pull up a chair and set it by a study or dinner table. Ask a friend to sit on the chair, making sure that the left side of your friend’s body is beside the table. Place your friend’s left arm on the table, palms up, and tell your friend to relax.
  2. Attach the BP monitor on your friend’s arm based on the instructions and proceed with taking your friend’s BP. Document your friend’s systolic and diastolic blood pressure.
    Systolic blood pressure is the top part of the BP reading which is the measure of arterial pressure when the heart is beating. Diastolic blood pressure is the bottom part of the reading which is the measure of the arterial pressure when the heart rests.
  3. Write down your measurements in your designated notebook.
  4. Prepare the hot tub and ask your friend to get in it. As you do so, set your stopwatch for about 15 minutes. After this time, dry your friend’s left arm and take your friend’s BP again. Document the reading in your notebook.
  5. Find out the difference in percentages by dividing your initial reading by your second reading for systolic and diastolic blood pressures.
  6. If the difference you get is more than 1, then your friend’s blood pressure was raised in the hot tub. A difference of less than 1 means your friend’s blood pressure went down by ten percent.
  7. You can repeat the experiment with your other friends, so you can establish if hot tubs can raise or lower blood pressure.


Your friend’s BP will have lowered a bit by around 5% after soaking for five minutes in the hot tub.

Many things can alter your BP. Ordinary daily activities such as walking or sitting can do this. Even more so when you are stressed. Sleep and relaxation can make your BP go down significantly.

In this experiment, vasodilation if the cause of dizziness and the lowering of your friend’s blood pressure. Hight temperatures make your muscles and blood vessels relax. In orthostatic hypotension, BP lowers after sitting down or standing up. This can be aggravated by some time spent in the hot tub, leading to dizziness.

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