Why Does Stamina Improve Quickly When You Do Cardio?

Anyone who is newly into cardio workouts would see their stamina improve quickly. I used to be someone with poor stamina. As I got more and more into cardio, I rapidly improved my stamina. My goal was actually just to get fit. I never really intended to focus on my stamina but it just happened to be a nice bonus. That is precisely what made me curious about the concept.

Questions like “What exactly is stamina?” and “How is it related to cardio?” started flashing in my head. In this article, I try to answer these questions. As usual, I will be using simple language with no non-sense subject jargon.

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What is Stamina?

To begin, it makes sense to take the time to understand what exactly stamina is. The word stamina has Latin roots from ‘Stamen’, and represented the threads spun fate. It was first used in the eighteenth century in the English language in the context of ‘power to resist or recover’. Over the years, it has been used to represent the mental or bodily capacity of an individual to sustain a prolonged effort or activity. The word is also closely related to endurance.

So, in short, we could say that stamina is a measure of a person’s ability to sustain intense activities, be it physical or mental. In this article, I’m focusing on physical ability; we’ll save the mental ability for another time. We could try and scientifically objectify the measure of stamina, but no one ever hardly uses such measures except for athletes. To keep it practical, I would say that one could measure stamina relatively or comparatively in the following manner: if a person feels exhausted after 10 minutes of running on day 1, and if the same person feels exhausted after 30 minutes of running on day 10, the person has improved his or her stamina within those ten days.

Of course, if you are an athlete, feel free to go bonkers with scientific measures. But my aim with this article is to provide answers practical enough for mere mortals.

The Factors That Affect Physical Stamina

There are two factors when it comes to physical stamina: the lungs and the heart. Together, these comprise the main components of the cardiovascular system. Whenever someone does cardiovascular exercise (what we call ‘cardio’) like running, cycling, or swimming, the efficiency of the cardiovascular system is improved.  As a result, one’s stamina also improves. That’s the short version of the answer. But how exactly are the heart and the lungs related to stamina? What actually changes after cardio exercise?

The Human Cardio Machine

Whenever you undergo cardio exercise, you also exercise your heart. Due to the physical loads involved, the left ventricle (a heart chamber that pumps blood) gets stronger. This is very similar to someone building biceps by doing curls with dumbbells. The left ventricle (chamber) actually increases in size and strength. So, it not only pumps larger volumes of blood but can pump blood out with more force. This means that body parts that are far away from the heart also start receiving circulation more efficiently.

Amateur runners often feel that their either leg-limited or lung-limited. In other words, when they try to push, beyond a certain point they either feel pain in their legs or run out of breath. Usually, the pain in the legs is associated with the inability of the heart to pump blood fast enough to the legs. And when someone runs out of breath, it is attributed to lung capacity.

The lungs are a necessary component of this whole system but are surprisingly not a major factor in stamina. Usually, both ‘pain in the legs’ and ‘breath shortage’ are actually caused by the lack of the heart’s ability to pump blood fast enough. The lungs just react to this phenomenon, and try to compensate. This also explains why we call cardio workouts ‘cardio’! The word is directly related to the heart. Of course, the caveat here is that there is no lung damage. If there is genuine lung damage, then lung capacity really does affect stamina. But this is seen only in extreme cases.

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How is Stamina Related to the Cardiovascular System?

Chemically speaking, stamina is related to a process known as acidosis. Stamina is in part scientifically measured using an acidity reading of the blood. In short, acidosis is a limiting factor for stamina. As you work out, your blood starts filling up with excess hydrogen ions that are excreted by the various body parts. These excess hydrogen ions in turn make the blood acidic.

When the acidity increases, haemoglobin (a compound that gives blood its red colour) starts losing its ability to stick to oxygen. As a result, your various body parts end up receiving lesser and lesser oxygen. Finally, you feel exhausted. The human body works best at a homeostatic pH (measure of acidity), which is a fancy way of saying that the body doesn’t like it beyond a certain threshold of acidity.

How Does Stamina Improve Quickly?

When you feel your lungs breathing faster during a run, your lungs are actually trying to compensate for your heart’s inefficiency. Imagine that the wheels of a car are trying to spin faster because the engine is not strong enough. The solution is to improve the engine and not waste time with the wheels. In other words, if you wish to improve stamina quickly, focus on the heart and not the lungs.

The easiest way to strengthen the heart and improve its efficiency is to design a regular cardio workout schedule and introduce sufficient variations in intensities of the workouts. Since I am not an expert in the field of physical exercise or health, I would suggest that you get further information from a qualified professional. All the best!

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Further reading that might interest you: What Really Happens To Your Knees When You Gain 1 Kg? and How To Be More Mindful And Not Get Lost In Thought?

Disclaimer: I am not presenting any medical or life advice in this article. For that kind of thing, you will need to contact a qualified professional (which I am not). All I am trying to present here is objective knowledge that you can benefit from. In the end, you, and you alone are responsible for your actions.