The effect of altitude and intensity of physical activity on the exergy efficiency of respiratory system

Abstract

The effect of altitude on exercise performance of lowlanders has long been discussed, but it is still unclear whether the performance reduction is related to inefficiency of the respiratory system, body tissues or both. In the present work, exergy analysis was applied to the human body in order to compare its exergy efficiency under basal conditions and during physical activity at sea level and high altitudes for different periods of acclimatization. Two control volumes were analyzed: respiratory system and human body as a whole. Data concerning mass and energy balances of the body and respiratory system were obtained from models available in the literature, which were modified based on medical literature to simulate the responses to physical activity at high altitude for different periods of acclimatization. The results indicated that the respiratory system exergy efficiency is reduced at high altitudes and under physical activity, while exergy efficiency of the body increases for both parameters, which may indicate that the discomfort reported at high altitudes is mostly related to the respiratory system than to the other ones. Concerning the acclimatization period, its influence was more pronounced on the respiratory system.

Exergy Analysis of the Musculoskeletal System Efficiency during Aerobic and Anaerobic Activities

“…These analyses related the destroyed exergy and exergy transfer to the environment with the predicted mean vote. Later, some applications in medicine were found in the literature for the whole body [24,25], in organs or systems [25][26][27][28] and in sports or muscle evaluation [29][30][31][32][33]. There is even a review that discusses the importance of exergy analysis in each research field [34].…”

“…It is important to highlight that the application of energy and exergy analysis to the human body in different conditions was already validated and extensively used in the literature by different authors [5,[11][12][13][14][15][16][17][18][19][20][21][22][23]25,26,[29][30][31][32][33]36]. The distinguishing feature of this article is the application to actual experimental results as in [5] for sports purposes and with the actual performed power known as an input variable.…”

Human body exergy analysis and the assessment of thermal comfort conditions

“…Albuquerque-Neto et al [23], Henriques et al [24] and Mady et al [25] applied the exergy analysis to the human body during physical activities. Moreover, this analysis was also applied in cancerous [26] and neurons [27] cells.…”

A thermodynamic assessment of therapeutic hypothermia techniques

“…(11). The first term is related to the exergy of vaporization of the sweat on the skin and the second term is related to the difference in the concentration of saturated vapor near the skin and concentration of the vapor in the environment.…”

“…Batato et al [9] proposed a pioneer model to perform the exergy analysis to the human body. Later, Albuquerque eNeto et al [10], Henriques et al [11] and Mady et al [12] applied the exergy analysis to the human body during running tests on a treadmill. Several authors [13e23] tried to correlate the points of minimum destroyed exergy with thermal comfort and thermal sensation conditions.…”