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Entropy 2008, 10(2), 100-123; doi:10.3390/entropy-e10020100
Article

Entropy Generation and Human Aging: Lifespan Entropy and Effect of Physical Activity Level

 and *
Received: 17 December 2007; in revised form: 17 June 2008 / Accepted: 18 June 2008 / Published: 20 June 2008
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Abstract: The first and second laws of thermodynamics were applied to biochemical reactions typical of human metabolism. An open-system model was used for a human body. Energy conservation, availability and entropy balances were performed to obtain the entropy generated for the main food components. Quantitative results for entropy generation were obtained as a function of age using the databases from the U.S. Food and Nutrition Board (FNB) and Centers for Disease Control and Prevention (CDC), which provide energy requirements and food intake composition as a function of age, weight and stature. Numerical integration was performed through human lifespan for different levels of physical activity. Results were presented and analyzed. Entropy generated over the lifespan of average individuals (natural death) was found to be 11,404 kJ/ºK per kg of body mass with a rate of generation three times higher on infants than on the elderly. The entropy generated predicts a life span of 73.78 and 81.61 years for the average U.S. male and female individuals respectively, which are values that closely match the average lifespan from statistics (74.63 and 80.36 years). From the analysis of the effect of different activity levels, it is shown that entropy generated increases with physical activity, suggesting that exercise should be kept to a “healthy minimum” if entropy generation is to be minimized.
Keywords: Biothermodynamics; Metabolism; Entropy; Entropy generation; Human lifespan; Aging; Biological system Biothermodynamics; Metabolism; Entropy; Entropy generation; Human lifespan; Aging; Biological system
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Silva, C.; Annamalai, K. Entropy Generation and Human Aging: Lifespan Entropy and Effect of Physical Activity Level. Entropy 2008, 10, 100-123.

AMA Style

Silva C, Annamalai K. Entropy Generation and Human Aging: Lifespan Entropy and Effect of Physical Activity Level. Entropy. 2008; 10(2):100-123.

Chicago/Turabian Style

Silva, Carlos; Annamalai, Kalyan. 2008. "Entropy Generation and Human Aging: Lifespan Entropy and Effect of Physical Activity Level." Entropy 10, no. 2: 100-123.


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