For example you could be super in shape from a muscular perspective but have really bad cardio and vice versa.
How is cardio different from physical shape and what exactly happens in your body that makes you have more cardio?
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>For example you could be super in shape from a muscular perspective, but have really bad cardio and vice versa.
That usually happens as a result of hypertrophy, which is caused by steroid use. People who are muscular without good cardio-vascular health are, almost without exception, that way because they’re cheating chemically. If you exercise enough without them to obtain gains, you are going to get better heart function.
Now, I should disclaim here that carrying more muscle mass *reduces your endurance*. This is why marathon runners are skinny: all that muscle requires sugar and oxygen to fuel, and those inputs must be delivered by your circulatory system. So if you’re musclebound, that’s not “bad cardio”, you’re just metabolically expensive to support, the difference between a SUV and a motorcycle.
Now, doing cardio is beneficial in and of itself. It exercises your heart, with more intensity than your skeletal muscles, which is important because your heart muscles are a different type of muscle, which are much harder to strengthen. You can’t lift anything with your heart, so all you can really do is raise your heart rate and make the muscle work faster, over short and long periods of time.
But the thing is, all the cardio in the world still won’t make a bodybuilder able to beat that marathon runner. If you want a very good object lesson in this, watch Tour de France races. The sprinters are big and muscular, the mountain climbers thin and light. No matter how much you exercise your heart, it’s still only a pump of a certain capacity.
Think of your body like a city.
Lifting weights = building muscles = building housing and facilities in the city.
Doing cardio = building your cardiovascular system = building highways and transits and terminals to move people around.
No city survives if you have a million condos but no transit and small, pothole-filled roads.
No body survives very long with lots of muscles but terrible cardiovascular system to support it.
Apart from what’s already been mentioned, it is theorized that when your heart rate is going during a cardio workout your brain de-prioritizes cognition and instead re-allocates resources to aid movement / metabolism. This can reduce stress / stuck thoughts. This is called the [transient hypofrontality hypothesis](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6723384/) and is thought to be a contributing factor to “the runner’s high”. It is harder to get this with weights since the high-intensity periods don’t last as long vs. cardio. Transient = temporary, Hypo=less, frontal=frontal cortex of brain (executive planning center). transient hypofrontal = temporary reduction of cognition, like your brain can relax and doesn’t have to think so much for a little while, kinda like meditation.
Your body acts on the bare minimun of what needs to be better. If you do max strength that will be better but stamina sucks. If you only do cardio max strength won’t differ as much from max-endurance as with “normal” people.
Your body only gets better at what you do so keep that in mind with of course all the other comments regarding that issue.
Edit: Typo
In respect to your heart, cardio will increase the volume of blood the right and left chambers (ventricles) can hold. Meaning your heart can take on a greater amount of blood while it fills in between heartbeats. This means the heart can now pump more blood per beat. This is why runner’s typically have a lower resting heart rate. Their hearts don’t need to beat as often as to move the same volume of blood as someone who is not “cardio-adapted”.
Now, just like a skeletal muscle (e.g., bicep, quad, etc..) gets bigger (hypertrophies), the heart can also hypertrophy. This usually manifests itself as a thickening of the left side (left ventricle). This allows the heart to generate more pressure (i.e., contract with more force). This type of adaption is not typically brought to fruition through cardio, but rather through weight training. Too much hypertrophy (thickening) of the left ventricle can be pathological (normal weightlifting will not push your heart to this extent, don’t be scared to lift weights!). This is typically only brought about by diseases or unhealthy lifestyles that lead to increased blood pressure like alcohol abuse, drugs, too much sodium, anabolic steroid use, etc.. The reason having “too thick” of a heart is bad is because as the heart the thickens, the chamber size decreases, meaning the less blood it can fill with in between beats. Which leads to the heart having to work harder (beat more often) to move the same volume of blood as someone who’s heart is not in this condition.
I recently went to a learn-to-ride-a-dirtbike course. It was for beginners so nothing extreme, but they teach you to stand as much as possible for better control. Now my legs, forearms, and traps are killing me.
I don’t know if I need more cardio (to at least help the biggest problem: my legs: they’re like noodles the next day) or if it’s basic strength training?
I know this is off-topic. I just am also interested in what cardio primarily improves.
I used to be able to answer this really well, but been a few years
Cardio will make the heart bigger by about 50%. Think about swapping a little 4cyclder engine for a big v8. The volume inside the heart has gotten bigger, meaning it can pump more blood. More blood means more energy. Meaning go faster for longer.
Lifting weights makes the heart bigger too, but it increases the heart muscles, not the volume. It does this to deal with the pressure increases that come with lifting weight. Think of this as the engine mount. If you chuck that v8 into your little car it will shake the car apart. So in this case, the heart walls get bigger, thus increasing pressure, to push the blood to where it needs.
Other things come into play, for instance, hermatcrit (red blood cells) increase, by up to about 3% of total blood volume (doesn’t sound like a lot, but it works out to about an increase of 10% extra oxygen). RBC’s transport oxygen and energy to the muscles, so using our car analogy, we’re now running on premium fuel.
Cardio is also region/activity specific. If you cycle lots, you’re body adjusts by creating new blood vessels in your legs, to allow more blood. This helps a little if you start running, but not so much if you start swimming. Because the body ‘learns’ to use the muscles and blood in a certain fashion.
Finally there is waste removal. This gets a bit more complex, but this is things like lactate buffering, and expelling co2, and honestly I can’t remember it well enough to ELI5, but it boils down to body gets good at removing waste product through breathing.
Now for the more complex: the big thing is heart. The average body needs about 5-6L of blood per minute, with a normal heart volume of about 80ml per pump, and a heart rate of 75beats is 80ml x 75bpm = 6L/min. During exercise, the heart increases by 50%, so is now pumping out 120ml, and let’s say it gets to 200bpm= 120ml x 200= 24L/min. But let’s say you’re fit. Real fit, and you’re heart at rest is 120ml. You still only need 6L at rest, so you’re resting heart rate is about 50bpm. But you start exercising, and your heart increases by 50%, you’re now pumping 180ml per beat, and you still hit the 200bpm, it’s now 180 x 200= 36L /min which is a shit load more work you can do.
Long, relatively low exertion cardio exercise 1) enhances fat metabolism, 2) creates new capillaries in the working muscles, 3) increases capacity to recover from exercises, 4) increases muscle stamina, 5) lowers both resting heart rate and blood pressure, 6) burns fat most intensively from the places where it’s most harmful: first and foremost from the liver, and secondly around other internal organs.
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