How come, since your just sitting there not doing any activity?
No answer, but a related question: How come when I’m in a hot tub, I feel just fine when the water level is low, but if the water goes over my sternum (and exactly my sternum), I feel woozy and out of breath.
WAG: An attempt to shed excess head by increasing circulation to your skin?
You should probably get out of the tub and cool off a little…
is it the same in the pool?
water exerts a significant force onto your chest. This’ll inhibit breathing.
Your heart rate increases to force blood to the surface of your skin where it can be released in an effort to regulate your temperature.
And it can be a serious problem if there’s a heart condition. A heart specialist friend of my folks explained this to me when Jim Morrison died: that it might have been due to a heart attack due to too-hot bathwater.
can it help improve cardiovascular health since it exercises the heart?
Cool!! Now I know how to get rid of those extra heads that have been growing out of my back!
OK, lets get down to facts about why this happens, not the speculation that’s been posted in the thread so far.
When you sit in very hot water, it dilates the capillaries and other blood vessels in the skin. That’s a typical response to heat, as the body tries to dump excess body heat into the environment.
But often it causes a drop in blood pressure, as excess blood pools in the circulatory system. In extreme cases the systolic pressure may drop to 80 or lower, and the diastolic down to 40 or less. Suddenly the heart has to pump twice as fast to try to sustain a viable blood pressure, and the autonomic nervous system reflexively increases respirations try to oxygenate what blood is passing thru the lungs even more, to compensate for the drop in volume.
The more of the body that is immersed in the hot water, the greater the potential for this to happen.
QtM, MD
Not a chance.
It’s like breaking in your car by revving the engine in the driveway, rather than driving it around and giving all parts a workout. Cardiovascular fitness comes from exercising all your muscles aerobically. Heart rate is just one crude way to measure the effectiveness of the exercise. Measuring oxygen consumption would be a far better way to measure it. But that’s hard to do at home. 