What is exactly stamina? What happens when it gets trained? Do your lungs get better and more efficient at pumping air?
In: Biology
People are talking about the Vo2 max which is fine and dandy and all and has affects but muscular endurance matters a lot.
The efficientcy of mitochondria in the muscle, the ability to use fat vs glycogen for energy. It’s why being a professional cyclist helps a little bit with swimming but not all that much. You have trained the legs to efficiently do things, but not the arms.
There’s two critical components:
– Your muscles have batteries that can be both used immediately (glycogen stores). This energy is just “ready to go” immediately if you need to act quickly or do something explosive, but it starts to be very noticeable as you consume these stores. The byproduct of this process can either be converted back into this explosive fuel or it can be directly consumed, but to do so, you have to used the other component…
– Combustion! You use O2 to blow up fuels and convert it to water, CO2 and energy. The more air you can get your body to uptake, the more you can output. But this part is much less stamina, per se. In theory, you can do this part more or less forever.
The two processes can work together to endlessly use and replenish your energy stores to go a bit harder for longer than you could on just could on using O2 alone. But once you cross and unsustainable threshold, you start eating into the energy stores faster than you can rebuild. Soon you start telling your muscles to just go and they just won’t! You have to really “dig deep” to activate even more muscles fibers to make up for the ones that try to work but don’t have enough fuel. Some people can or are willing to push harder than others through this, but eventually we all give out.
Speed juice. You get tired. No. Your bloodflow increases and you breath faster to supply your body with O2.
Another component of stamina is the amount of hemoglobin in our blood. Hemoglobin is on red blood cells and is what carries the oxygen from our lungs to our muscles. When you do endurance training, your body will respond by making more hemoglobin. The higher the amount of hemoglobin in your blood, the more oxygen you can get to your muscles with each heart beat.
Pro athletes take drugs to increase hemoglobin, or will sometimes do “blood doping”, where they remove a bunch of their own blood, concentrate the red blood cells, save it in a freezer, wait for their body to replace the missing red blood cells, then reinject the original blood cells into their veins giving them a higher concentration than when they started.
One thing I’m not seeing or maybe missed:
The sore/tired feeling in your muscles comes from a build up of lactic acid. Consistent cardio training not only reduces the rate of lactic acid buildup (through VO2 max gains – already mentioned), but hepatic efficiency at metabolizing lactic acid ALSO improves – this allowing more exertion with the same buildup or reducing buildup for a given exertion level.
There are also physical changes – runners will find more efficient strides: look at how an olympians legs move vs your own, watch how their upper body moves (it doesn’t much).
Intercostal muscles and the diaphragm can get stronger allowing for a larger chest cavity expansion and more aggressive exhale.
Some endurance athletes are even able to tap into some portions of the mammalian dive reflex – the spleen can contract and pump excess red blood cells into the bloodstream allowing for better gas transport.
Heart chambers get bigger, so it can pump more blood per minute. Blood gets more red blood cells, so the same amount of blood can carry more oxygen. Individual cells will get more mitochondria (the cell machines that turn oxygen into fuel), making them able to better use oxygen available. Blood vessels grow to the used parts of the body, getting more blood to relevant areas. Other structural changes happen too, like bones, connective tissue etc all adapt. Muscle cells get a somewhat higher mix of Type I fibers that use oxygen for fuel. And last but not least, technique. You’ll be able to do the movement more efficiently over time, wasting less energy so your ‘fuel economy’ improves.
Cardio adaptations tend to be a bit more short lived, so people can lose a lot of their cardio capacity in just a week or two of not training, but it also improves quickly. Someone who’s youngish and healthyish can go from ‘never runs’ to ‘can run a marathon without stopping’ in six months.
Looked most of the way down and no one mentioned build up of acid in muscles. I’m no expert, but I believe a person with higher endurance can push their muscles harder/longer. Muscles just literally give up at some point. You will not be able to move your leg with enough stength to actually run, then eventually you will not even be able to stand. I believe it’s lactic acid — a quick Bing will certainly tell you more than I can.
Muscles use oxygen to work. Your blood carries oxygen to your muscles. Breathing air puts more oxygen in your blood. Blood moves in your body through special kinds of pipes (arteries and veins). Your heart is the pump that makes blood move. When you start to exercise your body, the pipes become bigger, and your body creates more smaller kinds of pipes (capillaries). These are near your muscles to directly give them oxygen. When these pipes become bigger your heart needs to pump less to move the same amount of blood. Your heart becomes more efficient because of the better piping, your muscles receive oxygen more easily, and your stamina improves.
People are mistaken when they say they exercise to improve cardio (heart). They are improving the entire machine of blood and oxygen movement (cardiovascular system). As an example if you biked to improve your “cardio” (heart) it won’t necessarily improve your “cardio” (heart) for a different part of your body. For instance your improved biking “cardio” wouldn’t help you much if you had to use your arms to bike instead. This is because the leg piping system that was improved from biking didn’t improve your arm piping. It wasn’t your heart that improved your conditioning it was your piping (vascular).
What is even more interesting, the exercises benefits can be largely very specific. Tests have been done with people exercising “cardio” by biking with one leg. Their one leg stamina improved as expected. But there was no improvement when they needed to use the other leg. Their heart pumped efficiently with the exercised leg, but the heart was less efficient with the unexercised leg.
There is some transfer of stamina from one exercise to another. Running tends to improve a person’s stamina in other activities better than with biking or swimming, all common “cardio” exercises.
Most of this information is in the NSCA fundamentals of personal training handbook.
No, it’s more that your biology gets more efficient at physical activity via production of specialised cells and set points, so the physical stress is managed well enough to not trigger fatigue and exhaustion
Increased stroke volume, like other commenters have mentioned it has to do with the heart. Stroke volume is how much blood is pumped by the heart with each beat.
This is the same reason why athletes who are in excellent physical condition have an (on average) a lower heart rate at rest. Your heart doesn’t need to beat as many times to pump oxygen to your muscles because it’s able to pump larger amounts of blood with each contraction.
On a tangent related to stamina, a stronger heart doesn’t prevent a person from becoming tired but it does impact how fast one recovers from being tired, aka stamina.
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