Exercise is supposed to be good for the heart – how does forcing a finite organ to work harder not just wear it out faster?
In: Biology
Q=HR x SV
Q is cardiac output: how many litres of blood your heart pumps around your body. At rest this is about 5L
HR is heart rate: how many times your heart beats in a minute, on average about 72BPM
SV is stroke volume: how much blood your heart pumps out each time it beats, on average about 70ml
70×72=5020ml
Q (cardiac output) is constant for any given workload. Eg at rest the body will need about 5L of blood per minute, as you exercise, your body requires more blood, so it will increase both SV and HR. SV will increase by about 50% while HR can increase up to about 220-age (it can go higher but for physiological reasons it becomes inefficient).
Depending on the exercise, the heart can change in one of two ways, first it can grow in size, with a larger overall volume due to an increase in ventricular size (eg it can hold more blood), if it can hold more blood (say 100ml at rest rather than 70ml), our HR will come down; Q(5L)= HR x 100(SV), therefore HR = 50BPM.
Next, the size of the muscle fibres can grow (normally more through resistance training) which increases the power of the heart muscle. By having more power, it can push blood through the system easier, meaning the heart doesn’t have to work quite as hard. Think if you were trying to drain a pool, would you want a pump that came out of your mums decorative water fountain, or a fireman’s hose pump? The fountain pump would break before the job was done due to strain.
So the fact the heart is beating less, and not having to work quite as hard to push the blood through the system means the heart is healthier.
Now take into fact that exercise also has benefits of reducing lipids/triglycerides (fat) in the body, artery stiffness decreases (lower risk of stroke and clots), improved VO2 (ability to perform work), reduced risk of cancer, better mental health and performance, among a plethora of other advantages, not including benefits that go along with exercise (people that exercise are more likely to eat better and not smoke) you get better longevity outcomes and quality of life.
In saying that, at a certain point, you can over do it and cause damage. Elite athletes have higher mortality rates due to the prolonged stress they put on their hearts (by not allowing the body to rest fully, it doesn’t repair, heart included) along with the drugs and steroids they take including testosterone, EPO( increases red blood cell count= higher risk of clot), HGH (heart and organ swelling). They also have the risk that their HR can drop so low that they pass out (some athletes have been recorded to have resting HR as low as 20BPM during sleep).
TL;DR exercise improves heart size. Larger heart can pump more blood per stroke. Heart doesn’t have to pump as hard or as often to move same amount of blood around. Lazy you reaps the benefits of what sweaty you did in the past. Go exercise
Source: exercise scientist
Exercising takes uncontrolled strain off the heart and replaces it with controlled strain. That means if you do your exercises properly you’re slowly building up how much controlled strain your body can handle so you never overload it. This should reduce the uncontrolled strain you need to exert in daily life from everything including daily stress, to loosening a lug nut on a flat tire. These things can cause heart attacks, so preparing your body for that strain is the best thing you can do for your heart.
Once you understand your body on the most basic level you can truly understand how important exercise is. Simple breakdown: The lungs collect oxygen, the blood absorbs that oxygen, and the heart pumps that oxygenated blood to your brain and muscles. This is how muscles survive.
If you’re going to loosen a lug nut on your car with no muscles, you will need a lot more breathing from your lungs and a lot more pumping from your heart to achieve your goal. With consistent exercise, loosening a lug nut will rely much more on your muscles, and your lungs and heart can do their jobs much more easily by simply replenishing whatever blood and oxygen your muscles use, which won’t be much.
So working out your heart in the short term causes a little bit of strain, but that’s to protect your heart from an abundance of strain later on. Your heart may not get *a lot* stronger, but it will be protected by your muscles and lungs which will give it longevity to help prevent a stress-related heart attack.
The heart is a muscle, so it become more efficient when it is strained, just like your biceps.
Work it out, take it for a tumble, it becomes better at what it does.
Might sound like a silly question, but what about occasional use of drugs that speed up the heart rate? Would it have a similar affect?
Your arteries hold blood, but they also get clogged up by fat. If there is a clog, then the heart doesn’t circulate blood as well, which is bad for your body and also bad for your heart.
When your heart beats normally, the fat can form into clogs. When your heart beats faster it also beats harder, which dislodges some fat. This clears up your arteries, so when it goes back to normal pace the arteries are more clear.
ALSO, exercise makes your blood vessels wider. This means that even if you don’t have fat in your arteries, exercise still helps your blood flow better.
ALSO, exercise causes your body to release chemicals that regenerate muscle (oxytocin). This means that if your heart has ever suffered any damage, some exercise will help it to recover.
ALSO, exercise makes your heart grow stronger (and bigger). That means you end up with more heart muscle which means pumping blood becomes easier.
ALSO, exercise is good for your body in general. Everything in your body works better with exercise, and if your other organs are working better then they will keep the heart healthier too.
Simple terms
Conditioned runners have lower resting heart rates (beats of the heart per minute while at rest) compared to non conditioned runners this is because they have through training increased the efficiency of the heart and its ability to supply oxygen to the body.
In the long term amount of time they spent making their heart work harder is far offset by the time they spend either at rest or doing activities that don’t require the heart rate to increase much. A normal heart rate is 60-100 beats per minute, a conditioned runner could be in the low 40s per minute.
Over the course of a day of my heart rate was at 45bpm (beats per minute) and yours was 100bpm and we both spent the entire day resting my heart would’ve beat 64,800 times during the whole day compared to your 144,000 times. That would mean that your heart worked over twice as hard as mine did!
Those numbers would be if we both were at rest which means over the course of a normal day where we did things we’d see higher numbers. I run and the highest number I can find that managed to I pushed my heart rate was 184bpm and that was on a hill and didn’t stay that high when I was back on level ground. Even in a scenario where we keep those two numbers I calculated above and say we add two hours to the day where I pushed my heart rate to 184 it wouldn’t push my daily total over 100,000 and it’d still mean my heart didn’t have to push itself as much during the course of the day as yours did
Finally the more you weigh the more blood you have to move through your body. You can move more blood through the body by either increasing the amount the heart ejects each beat or you could increase the amount of contractions (bpm) the heart has. The heart in cases of obesity compensates by become bigger and more muscular (sounds good, but it’s not) it does this by increasing the thickness of its walls. This makes it harder for the heart to relax after it’s contracted. The heart continues to grow larger and more muscular as the individual grows heavier. Cycle through this a variable amount of times and we’ve got ourselves a situation where the heart just can’t keep up and
Is that you Donald? if so quit being such a twat.
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