Originally Posted by andreasl33
I have heard that many times, but could not quite grasp the physics behind the statement.
"Tense muscles make you sink."
...Tense muscles are not able to perform the movements as precisely as relaxed muscles and therefore one sinks? Or we get tired earlier, which slows us down and makes us sink?
Any comments welcome...
All of the above might contribute. Perhaps when you are relaxed you let the water support you more, whereas when you are tense you fight it.
Water is 880 times denser than air. That's good news and bad news. It's dense enough to support you if you let it, and dense enough to win every time if you fight it.