All fitness experts recommended that aerobic exercise increase the heart rate but we also know that caffeine, anxiety also can increase our heart rate, then why doctors recommend to do aerobic exercises to increase heart rate.
The answers below explain reasons for this in detail.
MD here. 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”?
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?
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 like yourself, drinking caffeine in large amounts will drive your heartrate 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.
Exercise is probably good for you, but if you’re a marathoner with a massively hypertrophied heart and a resting heartrate 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.
Aerobic exercise helps increase both your heart rate and oxygen intake, so your heart has the “fuel” to match the speed.Having a fast heart rate alone, without the increased oxygen intake, could put strain on the heart and could lead to heart spasms, which in the worse case scenario, could lead to cardiac arrest
Keep in mind caffeine also constricts the blood vessels which increases blood pressure. If you’re a normal healthy human a little caffeine could provide some benefits during exercise which outweigh the negatives. If you’re overweight, already have high blood pressure, or suffer from cardiac issues you’d be rolling the dice.
When you exercise, your body is responding to external stress, and raises its metabolic response appropriately. Not only does your heart rate increase, but your peripheral arteries dilate (allowing blood to flow to your muscles), while your other unconscious processes (such as digestion) are put on hold and receive less blood. (This is why you can get stomach cramps if you exercise too soon after a large, heavy meal, and why coffee can make you need to poop even if you haven’t eaten anything in a while.) Additionally, certain chemicals are released and energy is converted from storage to active use and then utilized to exercise.
When your rate is chemically increased, none of these responses occur. Your body may be forced to enter “fight or flight” mode, but the energy being produced isn’t going anywhere, and is typically converted to visceral fat (no matter where it came from) if it’s not used. It’s exactly the same reason a high-stress environment combined with a sedentary lifestyle can result in abdominal obesity.
I’m talking about straight caffeine. I can’t recall the dosages off the top of my head, but 1-2 cups of coffee a day aren’t really going to push your BP up very high unless you have a caffeine sensitivity (like me). Ten coffees over the course of a day? Yeah, you’re probably seeing some shit. Note that everyone’s physiology is slightly different, and caffeine resistance is definitely a thing you can develop. If you’re concerned, pick up a home BP cuff (most drugstores sell an automatic cuff; it might be a little pricey but if you’re worried it can be worth it) or talk to your PCP.
The bottom line: Exercise, by definition, is the use of external physical stimuli to increase performance. Using chemicals (caffeine, atropine, epinephrine, etc.) to induce the exercise response without actually exercising doesn’t produce any results
It’s not just the increased heart rate that’s the benefit, it’s all the other things that’s happening along with it when you’re exercising that together creates the net benefit. Going by heart rate is because it’s the easiest metric to tell if you’re getting a sufficient amount of exercise.
When you’re exercising, your body needs to deliver more oxygen (and thus blood) to your muscle tissue. This results in the blood vessels opening up and the heart rate increasing to push that blood along. In general, your blood pressure doesn’t increase by much, if at all. Your heart is working faster, but it’s not working harder per squeeze.
Things like stress or certain drugs increase your heart rate, but they don’t result in a corresponding opening of the blood vessels. In fact, in the case of some drugs, the opposite will occur and your blood vessels will constrict. With your heart pushing faster through blood vessel or same or smaller diameter, this results in an increase in blood pressure. It’s that chronic exposure to the increased blood pressure that can cause problems – it stresses the muscles in the heart and the blood vessel linings. And this is all because the heart is having to squeeze harder than before due to this increased pressure.
So in short, exercise good cause heart rate is matched by opening blood vessels. Other sources don’t open blood vessels, so your blood pressure rises, which is bad.