What is happening on a cellular level when your body gains cardiovascular endurance?



This is probably a poorly written question but what is happening to the body as we gradually get better cardiovascular endurance. What has to happen for someone go from running a mile to a marathon?

In: Biology

Your heart pumps blood more efficiently. Effectively, a singular beat of your heart is capable of moving the blood in your body a further distance; meaning, you are capable of circulating oxygen throughout your body with less energy needing to be inputted for additional beats. Similarly, your lungs begin to draw more air with less effort and tire less easily from deeper, heavy, more cumbersome/wasteful breathes. Both of these things in combination means that your body will overall produce less Lactic acid, and consequently feel less sore by continually pushing the boundaries and capabilities of your body. Eventually you build the capacity to “be able to take the next step” in running to be able to compete for a marathon. In fact, most marathon runners I know who run them for enjoyment and pushing themselves say they train just shy of a true marathon (who has the time of true capacity built for it outside of Olympic athletes?) 15,16,17 miles for training and letting the adrenaline of “runners high” carry them to the finish.

Many reasons. One of which is greater number of red blood cells. More oxygen can be transported at faster rate