On a cellular level, how does exercise make us healthy or improve our health?
In: Biology
In muscles, cells physically grow larger (hypertrophy) and move of them develop. When these muscle cells contract and relax they are capable of carrying a lot more force, which results in heavier objects (including the weight of your own body) being able to be moved easier (less calories spent) and increases the upper limit of what the muscle can support. This needs protein which is why a lot of athletes take protein shakes to supplement their diet with extra protein.
The cells also become better at absorbing nutrients from the bloodstream and expelling waste into the bloodstream or endocrine system to be filtered and removed by other organs so waste doesn’t build up in your cells. The cells can also store more ATP which is the raw chemical substances in food consumed by the mitochondria within your cells and that produces the energy to keep our bodies running, so bigger and better cells mean more energy stored meaning more energy produced. The cells can also consume resources more efficiently so your body uses less calories and can store more fat (the body ALWAYS wants to store fat, and it will deconstruct muscle tissue to build fat if you are on a cut, ie running a calorie deficit in order to lose weight). This goes for your heart too, so a stronger heart beats more slowly because it can exert more force per beat while saving energy in order to push blood around your body.
Good form in exercise is essential because this makes ganglia develop. Ganglia are small nerve clusters, basically the local authority for your nervous system, which are directly responsible for moving a specific set of muscles or limb. The better your form is, the more this ganglia develops, resulting in more precise and efficient movement which further saves energy and makes the muscles stronger. Dancers and ballerinas have incredibly developed ganglia and are very strong even though they tend to have smaller frames because their bodies are very highly co-ordinated.
All of this working together helps produce hormones and neurotransmitters. These are drugs your body produces to control your behaviour and bodily processes. GABA, serotonin, and dopamine have many many functions but their most important functions are making you happy, regulating sleep, digestion, and reduces the peaks and troughs in mood making your mood more stable. This is why exercise directly improves mental and emotional health. You also do most of your growing and healing while you’re asleep, so more exercise = more neurotransmitters = better sleep = better recovery from exercise, sickness, stress, etc.
Hormones like testosterone (produced in significant amounts by men but are only in trace amounts in women) are steroids which further promote muscle growth and development, which is why men are naturally stronger than women. Hormones produced by both sexes as a result of exercise increases sex drive, the health of the sex organs and sex cells, which results in better quality children (that said there is a significant amount of genetic and environmental effects that have a far larger impact on foetal development than exercise). Hormones also make other tissues like bone and cartilage and skin grow collagen (a dense elastic substance) which makes your bones bend rather than break (and when bone with high collagen does break it breaks cleanly rather than shatters which is far easier to heal) and your skin is tougher and firmer and can store more water, resulting in better looking and functioning skin.
Exercise isn’t very resource hungry. The human body is extremely efficient and you would have to run several marathons in order to run off a single cheeseburger. For that reason, athletes and dieters “cut” which is where they remove a meal and count calories because your body burns fat just by existing. It’s not recommended for fat or obese people to run because of the immense pressure that puts on their joints–lose weight at the dinner table first, then exercise. When people feel tired after exercising it is because they’ve used up their ATP reserves (the chemical energy used by cells). The body will eventually produce more ATP, but the more exercise you do the faster you will produce ATP, the more you can store, the less your cells will use, overall resulting in more exercise achievable and less effort being spent. Supplements like creatine are the raw amino acids which your body uses to make ATP, so athletes often take creatine to increase the amount of exercise they can do. Creatine isn’t a steroid, the amino acids are what your body tears food apart in order to use as fuel so creatine is a concentrated supplement of these amino acids to make ATP.
All of this adds up to make your body faster, stronger, tougher, and more efficient, as well as looking better and being resistant to damage from which is what we mean when we say “healthy”.
Inside our cells are tiny robots made of protein that pull strings also made of protein that make us move like puppets. When you exercise your body adapts by making more of these robots making you stronger and faster. It also makes a bunch of stuff to help the motors do their jobs better. [https://en.wikipedia.org/wiki/Motor_protein](https://en.wikipedia.org/wiki/Motor_protein)
There’s also a theory that a lot of cellular damage is caused by slightly malfunctioning mitochondria producing more free radicals (hungry molecules that want to bind with other stuff, damaging it in the process…like your DNA or other cellular machinery) as they generate energy.
Exercise may force these damaged mitochondria to work harder than they would normally and “kill” themselves in the effort, removing them from the cell, letting healthy mitochondria reproduce to take their place and reducing the number of free radicals floating around.
On a cellular level. That is a tricky one. We know the body is made up out of organs, that are made up out of tissues, that are made up out of cells.
‘Exercise’ is something that happens on the level of the organism, it does change the collective health of the group of cells that make up the organism, but not really in a way that one cell can be ‘exercised’ and have a different footprint.
We usually look for parameters in the blood to decide on health, being no high blood pressure, normal count of different types of blood cells, not too much fat in circulation, not too much sugar in circulation, not too much waste products in circulation, enough oxygen etc…
You can compare it to a house, you can’t actually see the people living in the house, but if you can analyze the waste they put out (vegetable scraps or fastfood wrappers?) and you can see which groceries they bring in, you might have a good idea of the general health of the people in the house. Now, if you look at an apartment building, it becomes harder to define the building as healthy, as the guy from 3B is always smoking with his can of bud light, while the couple in 5D just returned from a weekend MTB trip. The same is true for the body, it’s hard to judge ‘overall’ health.
So,… what happens when you exercise. Exercise is actually muscle movement, which needs energy. Energy in the body comes from the food. The body stores energy in the liver and the fat tissue, so when you exercise, you take energy from that. Because you use your muscle tissue, the cells send out a signal that they are ‘heavily used’ and more muscle tissue grows. The fat tissue deteriorates when we burn more than we eat. It is still debated, but generally believed that it is the individual fat cells that reduce in size, and not the amount of fat cells that reduce (that amount is approx stable once you reach puberty).
So, on a cellular level, not too much happens, but the populations of cells, and their relative contribution to the body changes, also their energy streams change.
Ancient humans had to hunt or gather food to get energy. At the same time, ancient humans used a lot of energy (compared to other animals): Humans hunted by tracking and tiring other animals out. Human babies spend a lot of their life burning energy and not collecting energy. Human brains burn a lot of energy. Humans need a lot of energy.
Thus, human bodies evolved to be very efficient: 1) Store extra energy as fat to not waste it 2) Only grow muscles that are used in order to conserve protein and energy.
But human society suddenly changed human behavior: We could get energy by just buying food. Because we could just buy food, we ate excess energy, which we store as fat. Because we could just buy food, we didn’t have to use as many muscles to gather food so we stopped building muscles.
Why is excess fat bad? Fats produce hormones. Hormones are signals or messages to the body about the state of the body. Hormones mostly signal based the *amount* of the hormone in the body. Too much fat, too much of fat’s hormones, and the body starts misbehaving. Fat also releases cytokines, which are not exactly hormones, but too many cytokines seem to constantly activate the immune system, which makes the immune system unable to respond to actual attacks.
Why is too little muscle bad? Well muscles help us move, help support us, and help prevent us from getting injured. Too little muscle and we get injured easily, can’t move well, and can’t support our own weight (and we get things like lower back pain and bad posture.) Muscle mass also tends to calm the immune system. And the other important muscle is the heart! If the heart isn’t challenged, it doesn’t get stronger and is less resilient, ~~and it pumps less blood per pump, which can contribute to high blood pressure.~~
TL;DR: Because energy was scarce, we evolved to store energy as fat and to only grow muscles when needed. When energy became abundant and easy to gather, we gained too much fat and lost too much muscle. Too much fat unbalanced the body and too little muscle leads to not being able to move well and more likely to get injured.
Cardio exercise is an attempt to reduce fat (though you can also eat less) and to strengthen the heart and breathing muscles. Resistance exercise (moving heavy objects) is an attempt to fool muscles into thinking they are needed, so the body will spend energy growing and maintaining those muscles.
There are really a lot of reasons. Exercising increases the amount of oxygen that your cells receive. Oxygen is necessary for your cells to create ATP, which is basically the energy source that fuels your cells.
Another reason is that when your cells replicate and DNA is copied, the DNA inevitably gets shorter. For this reason there is junk DNA at the ends of the strands called telomeres which act as a padding. It’s okay if this DNA gets shorter since it doesn’t code for anything important. Over the course of your life, the replication will make these telomeres so short that further replication will start affecting the DNA that codes for necessary proteins. This has many negative health effects, and cancer is one of them. Scientists have reported that people that exercise regularly have telomeres that look 20 years younger than those who lead a sedentary lifestyle. Exercising truly makes you live longer since it extends the amount of times your DNA can replicate.
This was actually part of my phd thesis. On a cellular level, when your muscle contracts, it produces some molecules that it can export to the blood. These molecules are called myokines.
One example of myokine is irisin. The muscle exports this molecule into the blood stream and when it reaches the brain, it can increase the production of a molecule calles BDNF, which is related to better memory.
Another example is KAT, a molecule that decreases the abundance of kynurenine in the blood. Kyrunenine levels are high during stress and is toxic to the brain, so exercise prevents the brain from being damaged during stressful sitiations.
Other molecules produced by the muscle help reduce inflammation in the whole body and others help you absorb more glucose after you eat, so it helps prevent diabetes.
Edit: thank you for the award
Shit, where do I begin?
Vetricular hypertrophy for cardiovascular health.
Muscular hypertrophy for athletic health
Heat shock proteins for anti aging
Androgenic upregulation for anti aging
Increased glucagon secreation to lower insulin
resistance to fight diabetes
Production of more alveoli for respiratory health
Increase in dopamine and norepinephrine pathways for mental health
Just actually moving your legs to avoid vascular infarctions
Increased nitrogen oxide production in salicary microbiota to reduce hypetension for cardiovascular health
Etc.
Not to mention all the benfits of losing extra fat.
Each one of these would be a long paragraph to explain. On the cellular level. There’s honestly just so many benefits to it, and I’m just scratching the surface with these examples.
It boosts Brain Derived Nootropic Factor (BDNF). If you want the whole runaround (pun intended) read or listen to *Spark* by John Ratey MD. It blew my mind, and I’ve been cycling the past 70 days straight since.
Edit: I’m not affiliated with the book
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