system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does it require energy to hold something heavy in a stationary position?

In physics today we were going over how work done (or energy) is equal to force multiplied by distance moved, but our teacher was unable to explain clearly why it requires so much energy to hold something stationary. If the object isn't being moved what is the chemical energy being converted to?
gpt
The physics class should also cover force diagrams. That heavy object has a downward force from gravity. To hold it above the ground requires an equal force upward. If you're holding it, this upward force is exerted by your muscles and skeleton. Your muscles require your body's energy to maintain that force. So while you may not be doing work by how physics defines work, you're still using energy to apply a force.