As a former biophysics major, I am fascinated by the concept of entropy. Most of us know entropy as it relates to spacial orderliness - the gradual decline of the kitchen sink or a closet into disorder. In thermodynamics, entropy - from a Greek word meaning “transformation” - may be thought of as a measure of the degree of energy degradation in any process. Entropy explains many phenomena within the human body.
Physico - Chemical Point of View
The machine that is the human body works to achieve equilibrium. Simply put, energy balance in the body involves receiving energy in form of fats, carbohydrates, and proteins, and transferring this energy to the surroundings as heat. Thermodynamically speaking, this means that ordered organic molecules are changed to totally unordered form of energy – heat.
Highly ordered systems carry low entropy. According to second thermodynamic principle, such a system, left to itself, inevitably deteriorates with time. In this way, the entropy theory of aging relates to the biological wear and tear theory. If aging is a result of damage accumulation in organisms accumulated over time, then maximum entropy results in corporeal death.
While maximum entropy may correspond to death, aging is related not only to how much metabolic work is performed but to how well the work is done. Daniel Hershey of the University of Cincinnati defines an “organic entropy” for homeothermic systems as ΔS=ΔQ/T, where ΔQ is the basal heat per unit weight per unit time given off by an organism, and T is isothermal temperature. Studies suggest that the figure 0.833 Kcal/Kg/hr represents universal characteristic for living tissue.
Entropy, Exercise, and BMR
The heat evolved by the body is called the basal metabolic rate (BMR). Different states of arousal, age, and even diet affect BMR. For example, Vegetarians have lower BMR than nonvegetarians with high proteins consumption.
The entropy production in mild exercise is 1.5-2.4 times as great as that in basal conditions. The entropy production in vigorous exercise is six to eight times as great as that before exercise. Studies suggest that strength training can increase BMR due to increases in lean muscle mass.
Keeping in mind the aforementioned description of entropy, one might conclude exercise is detrimental to longevity. However, it is important to look at the human body as a whole and not individual organ systems. Just small amount of physical activity indeed helps people live longer.
As one of my former professors stated, “Metabolism affects the heart, the heart affects the lungs, the lungs affect the blood, the blood affects the muscle, muscle affects hormones, and hormones affect metabolism!! It is hard to just study entropy and its effect on lifespan when other factors play a role in lifespan!!"
For more information, check out Entropy Theory of Aging Systems: Humans, Corporations and the Universe.
1 HEALTH, AGEING AND ENTROPY - http://www.ped.muni.cz/z21/knihy/2011/39/texty/eng/34_navratil_eng.pdf
2 Entropy Theory of Aging Systems: Humans, Corporations and the Universe
Author: Julia Anthony
B.S. Exercise Specialist, CSCS, NASM CPT