Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
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When you take a step, you are using up to 200 muscles.
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The average sperm cell swims at 8 inches per hour.
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Stress can result in more headaches as a result of the body rerouting blood flow to other parts of the body.
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Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
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An average heart beats 100,000 times a day, pumping some 2,000 gallons of blood through its chambers. Over a 70-year life span, that adds up to more than 2.5 billion heartbeats.
73
The human brain has the capacity to store everything that you experience.
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