Welcome to the Matter Realisations' Endurance Page

Endurance, or cardio-vascular endurance, has many parts. It involves a main pump (our heart) and many secondary pumps (the muscles surrounding capiliaries, and veins), a distribution system (blood vessels), and a gas/liquid diffusion transfer station (our lungs).

Improving our endurance may involve improvements in one or more of these parts.

Even with highly efficient pumping, distribution, and oxygen/carbon dioxide transfer systems; we are still limited by the holding capacity of the blood for oxygen and carbon dioxide. Genetics aside, some "athletes" have even found ways to cheat on oxygen holding capacity.

We are complicated machines, indeed!

Many chemical species move through the body through the aid of various components of the body. For example, most of the oxygen that is moved by the blood is carried by an iron containing molecule called hemoglobin. (Diving animals have appreciable amounts of a similar molecule called myoglobin.)

The most important part of this transport by hemoglobin, is that the oxygen is relatively easy to add to an empty site, and that it is relatively easy to remove from an occupied site. Carbon monoxide; a common poison produced in low temperature fires, such as cigarettes; binds much more tightly to the oxygen transport sites of hemoglobin than does oxygen. A person exposed to carbon monoxide has a much lower oxygen carrying capacity.

(This has been an anti-smoking ad. :-)

There are a number of ways in which the body responds to chronic cardio-vascular (aerobic) "stress":

• Increasing blood holding capacity for oxygen and carbon dioxide. Minimal.
• Increasing pumping capacity. This roughly translates as increased heart stroke volume, and results in a lower resting heart rate.
• Increasing surface area available for transporting oxygen to the muscles and carbon dioxide away from the muscles. Or, minimizing the distance over which the oxygen/carbon dioxide are transported. This is accomplished by increasing the number of capillary vessels in the muscles.
• Increasing the number of mitochondria in the muscle cells. These are the engines of the cell, and it is where the oxygen is consumed.
• Increased capiliarization of the lungs? (Apparently not.)

Extended intervals of raised work rate can result in an increase in the blood viscosity. This makes it harder for the heart (and secondary pumping system) to circulate blood. Taking in fluids, such as water, will help maintain (lower) viscosity.

Our life style and/or environment may also decrease our endurance:

• Smoking can cause a serious decrease in the available surface area to exchange oxygen and carbon dioxide in the lungs. Besides the binding of carbon monoxide to hemoglobin transport sites, cigarette/cigar/marijuana/whatever smoke contains "tar", which deposits on the lung surfaces. Effectively it makes our lungs smaller. Another way to think of this is that we are self-inflicting pneumonia on ourselves.
• Stress, and other things (like diet) which elevate the concentration of low density lipoproteins (cholesterol) and triglicerides will cause arterial plaques to form. This makes it more difficult for the heart to effectively circulate blood.

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