system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5:If heart is a muscle that never rests why other muscles need rest?
gpt
The heart actually does need rest. Every time your heart beats it goes through “Systole” which is contraction of the muscle, and “diastole” which is a resting period in which it refills with blood. Systole lasts about 0.3 seconds and diastole lasts about 0.5 second. So even though it seems like it’s constantly working it is actually resting more than it is working.