why is increased heart rate considered dangerous when it comes as a side effect of drugs (ie cocaine, marijuana) but considered beneficial and necessary when caused by aerobic exercise?

Question

I’ve even seen “increased risk of stroke” caused by this increase in heart rate. Something is not adding up here, why such a big difference?

In: 20

Answer 1

Many points have been answered but it’s also worth noting that it’s not just rate that’s important, it’s rhythm as well. The 4 chambers of the heart need to be precisely co-ordinated together for it to work best as a pump. Each of the two ventricles is filled by its corresponding atrium and it’s possible for all kinds of things to go wrong and they can get out of sync. For example, a ventricle won’t do much useful work if its atrium hasn’t just filled it with blood. It’s even possible for individual muscle fibres in the chambers to go out of sync with each other so it just sits there “fibrilllating”.

Many drugs (and cocaine is a biggy here) can cause this kind of thing. Not only is the heart *rate* raised with cocaine, the heart is more likely to develop an abnormal *rhythm*. Some abnormal rhythms might make you feel funny and increase the risk of a stroke. Some will cause you to have a cardiac arrest.