Basically what the title says. If exhaustion resulting from physical activity is caused because our body struggles to keep up with the metabolic energy demand of our body but pretty much every source says that our brains energy consumption does not vary significantly with the amount of mental effort that we are doing then what exactly causes mental fatigue and exhaustion.
In: 48
Eli5: If you are a healthy, able-bodied person, balancing is not usually an issue. You stand and walk with only minimal exhaustion. You can also run for a decent amount of time without getting too exhausted.
All of these tasks are so different, yet equally complex. Merely standing requires you fighting gravity. Walking requires this, plus added energy and coordination. Running requires all that, plus endurance and even more expended energy.
The average human’s brain function is probably similar to standing. You are actively parsing your surroundings for stimuli, but allowing yourself to daydream, plan ahead, etc.
When you actively try to focus on something, especially any sort of complex task that involves problem solving or adapting, that is more akin to running. In high stress environments, doing this same action is akin to sprinting. Unless you’re trained to endure it, your brain will fatigue quite easily when doing this.
Your brain is a muscle, but more like a series of muscles like your ‘core’. The harder you push it, the more it will tire, until it hits a ceiling, or raises it. Your body requires the same amount of energy to do complex tasks rapidly in high stress environments as it would to sprint for a very long distance.
I can’t get into the reasoning behind it not having as immediate if a physical effect (I.E.: weight loss, muscle growth)— this is beyond my level of knowledge and is slightly above ELI5
Not exactly ELI5, but analogies can be helpful
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