system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is cardio exercise good for your body, while using stimulant drugs is bad for it? They both increase your heart rate and make your body work so isn't taking the stimulants just a form of exercise for your heart/body?
gpt
**TLDR: You have to actually use your muscles if you want to increase your strength or endurance. Increased blood pressure from stimulants is way worse than the increased blood pressure from exercising.**

First off, when you do cardio regularly (and you eat right) your body detects the wear and tear on your body, and does maintenance to keep your muscles and bones strong enough to meet the increased workload. Everyone knows you can't get stronger/faster overnight, but over time your muscles and bones become better-suited to meet whatever tasks you've thrown at them lately. Stimulants are not going to "trick" your body into doing any of this.

Second, when you exercise, some of your blood vessels contract (get smaller) and some of them dilate (get bigger). They contract where oxygen demand is low so that blood will get to where it's needed faster, and dilate where oxygen is needed most. This increases overall blood pressure but that extra pressure is essential for your oxygen-hungry muscles.

However, with stimulants, your blood pressure goes up for no reason. Your body has no reason to increase blood flow if you aren't exercising. So, the extra pressure has nowhere to go and the heart works harder than necessary for nothing.