I have been working on improving my health. I read about glucose, ATP, oxygen delivery etc. But when I am cross training and pushing myself, what is happening in my muscles? Do you grow more capillaries to deliver more oxygen to clear waste? Lactate forms, and exercising with lactate present improves muscle “tolerance” to it. But again, what is improving? Does your body produce more enzymes?
Edit: I want to differentiate the training I am talking about versus traditional “over loading” weight lifting (muscles get bigger)
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I cannot give a complete and total answer, however, I have done a little research on this in the past and I do know that cellular changes occur. Specifically, the size and quantity of the mitochondria within the cell. If you recall from your science classes, mitochondria are the PowerHouse of the cell.
Interesting question, commenting for visibility.
So for aerobic exercise what changes as you work out? Stroke volume and heart rate and such? Or enzymes that increase aerobic respiration?
In simple terms, your muscles consist of two different kind of muscle fibers: Slow twitch and fast twitch fibers. Slow twitch fibers are very energy efficient, but produce less force. Fast twitch fibers use more energy, and produce more force.
The type of excercise will define what fibers will be used most, and those fibers will grow and multiply.
I recently saw a good video explaining the difference.
You’ve probably heard of ‘mitochondria’ which are the power convertors in your cells. The analogy is a bit simplistic, but you can think of them like batteries. Aerobic conditioning causes your cells to make more batteries, connected in parallel, so you can maintain effort longer. Anaerobic conditioning causes mitochondria to fuse together. In other words, it takes the batteries and joins them end to end, in series, so you can produce higher peak effort.
So, I’m not a specialist in physiotherapy, but I do work at an Epigenetics research lab.
I do know that exercise – both aerobic and anaerobic – induces epigenetic changes in pathways associated with energy metabolism and insulin sensitivity, contributing to healthy skeletal muscle.
This occurs through changes in Methylation (a molocule that tweaks your gene expression throughout your life) on DNA and specific RNA.
While your DNA has your body’s blueprint, or recipe book, and RNA copies down the recipes to be enacted, epigenetics determines which recipes are read, the dissemination of those instructions, and can tweak how the instructions are copied down to better suit your survival needs.
At the genetic level, regular exercise allows epigenetic markers to improve current molecular systems, and adjusts the body to *maintain* that better function in the near future, by tweaking gene expression, which then influence the rest of the body’s systems.
These epigenetic changes include reducing the speed of plaque formation in the vascular system, strengthening the heart, reducing overall inflammation, reducing mitochondrial death, regenerating muscle, slowing the development of fat tissue, and other metabolic processes. Exercise allows epigenetic markers to increase the expression of genes that suppress tumors, and reduces the expression of genes that can prompt cells to become tumors.
Given the complexity of existing literature, it’s not possible currently to give specific recommendations about the type, intensity or duration of exercise that would be beneficial for different subsets of the population. (Healthy, diseased (which disease?), trained or novice)
So I can’t say in aerobic or anaerobic would be *better* at doing this for you specifically, only that both DO this.
Early childhood development, even as far back as ‘in the womb’ can change how receptive or resistant an individual is to certain physiological changes, even at an epigenetic level. So the exercise that works very well for you won’t necessarily work for your neighbor to the same extent or effect.
Some people are epigenetically predisposed to lose weight very easily through fasting, while some are very resistant to it.
Some people build muscle very easily when exercising, while other people greatly struggle to gain muscle tissue.
While fitness bros *really* love to simplify things to ‘Calories in, Calories out’, the reality is far more complex.
So another part of doing aerobic exercise is that your resting heart rate will decrease because your body becomes more “efficient,” at receiving oxygen from your blood. This is because your body increases the amount of capillaries in your body (when oxygen is diffused from the blood into your body, and the CO2 from the body is diffused into the blood(where it is then taken to the lungs to exhale the CO2 and inhale oxygen))
I have a bachelors in Exercise Science btw
Muscles and the energy associated become expended which propegates the increase of entropy which is experienced as a negative.
Lactic acid…. not lactate.
Lactate is the generic name for lactase, the enzyme that breaks down lactose.
I see many mentions of mitochondria, this is correct but there are also other adaptations.
This includes neuro pathways that enable more effecient blood flow, increased cappilarization, increased diffusion in the lungs, larger blood volume, increased ability to remove waste products such as lactate, hydrogen and even cortisol.
The ELI5 would be your body learns to become more effecient at whatever stresses it the most. If you are training anaerobically this means fast delivery and removal. Take in more blood and glucose, deliver it quicker in the muscle and remove the byproducts as fast as possible.
Source: I am a Kinesiologist and CSEP CEP.
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