Why is it good for you to raise your heart rate through aerobic exercise but not through caffeine, stress, anxiety, etc?

From a Doctor

Long and short of it: we do not know. Saying something is “good for you” or “bad for you” is very challenging, given the huge variability from person to person. You know those commercials that say “consult with your doctor before trying this exercise program”? That’s why. Most online skew towards young and healthy, but the people I see are old, overweight, and sick.

Why Does Coffee Increase Longevity?

There are numerous studies showing that consuming large volumes of caffeinated coffee increases longevity and improves quality of life. Is that because of caffeine? Antioxidants? Social effects? Some confounding variable like a good job or exciting hobby that causes people who would be happier anyway to consume more coffee?

Stress and Exercise have Wide-Ranging Effects

We know that stress leads to increased levels of hormones like epinephrine (adrenaline) and cortisol. These hormones have wide-ranging effects beyond their immediate effects on the heart. Likewise, we know that exercise has a huge range of effects, from promoting the development of new neurons to promoting lower weight and better cholesterol levels that reduce the risk of atherosclerosis (one of the major forms of disease worldwide).

In a young person, drinking caffeine in large amounts will drive your heart rate up. Probably not a big deal. But in general, young people get their caffeine from drinks that have tons of sugar or fat (soft drinks or Starbucks-style abominations), so docs tend to make broad statements like “drink less caffeine.” Does that mean we know shit? No. Does that mean it’s actually bad for you? Who knows.

There’s Much In Medicine We Don’t Understand

Exercise is probably good for you, but if you’re a marathoner with a massively hypertrophied heart and a resting heart rate in the 40s, does that make you much healthier than someone who just exercises a moderate amount, doesn’t have bad cholesterol, or generally takes care of their health? I don’t know. In fact, it may put you at a disadvantage. Given that most of the health problems in the US revolve around obesity and its consequences, though, docs are very likely to recommend exercise.

Could all of this change? It sure could! Could some forms of chemical stress on the heart be good for it? Probably! But in the meantime, I’ll tell you the same things I tell everyone: get some exercise and avoid stress. Life just feels better when you do that stuff.

Studies Don’t Mean Much

And everyone here who pulls out a study showing one finding or another: I can probably find a study showing the opposite.