Exergy performance of human body under physical activities

Mady, Carlos Eduardo Keutenedjian; Neto, Cyro Albuquerque; Fernandes, Tiago Lazzaretti; Hernandez, Arnaldo José; Saldiva, Paulo Hilário Nascimento; Yanagihara, Jurandir Itizo; Oliveira, Silvio de

doi:10.1016/j.energy.2013.09.050

Cited by 37 publications

(62 citation statements)

References 25 publications

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“…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].…”

Section: Introductionmentioning

confidence: 99%

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

Spanghero

Neto

Fernandes

et al. 2018

Entropy

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Abstract:The first and second laws of thermodynamics were applied to the human body in order to evaluate the quality of the energy conversion during muscle activity. Such an implementation represents an important issue in the exergy analysis of the body, because there is a difficulty in the literature in evaluating the performed power in some activities. Hence, to have the performed work as an input in the exergy model, two types of exercises were evaluated: weight lifting and aerobic exercise on a stationary bicycle. To this aim, we performed a study of the aerobic and anaerobic reactions in the muscle cells, aiming at predicting the metabolic efficiency and muscle efficiency during exercises. Physiological data such as oxygen consumption, carbon dioxide production, skin and internal temperatures and performed power were measured. Results indicated that the exergy efficiency was around 4% in the weight lifting, whereas it could reach values as high as 30% for aerobic exercises. It has been shown that the stationary bicycle is a more adequate test for first correlations between exergy and performance indices.

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Section: Introductionmentioning

confidence: 99%

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

Spanghero

Neto

Fernandes

et al. 2018

Entropy

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“…Although the entropy production and destroyed exergy were already calculated for the whole body [5,6,15,17] and for the lung [16] during physical activities, the exergy efficiency of this organ has not yet been discussed. In the present work, destroyed exergy and exergy efficiency are calculated as a function of altitude and intensity of physical activity.…”

Section: Introductionmentioning

confidence: 99%

“…Results of Rahman [17] indicate that the entropy generation rate increases with the increment of exercise level. For Mady et al [15], the minimum entropy production principle is valid for people running, but exergy efficiency increases as a function of aging (different from the results for basal conditions) Albuquerque-Neto et al [16] made the first attempt to apply exergy analysis to respiratory system under physical activity. They evaluated exergy destruction in lungs and in tissues, and concluded that tissues are more effective than lungs during physical exercise.…”

Section: Introductionmentioning

confidence: 99%

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

Henriques¹,

Mady²,

Neto³

et al. 2014

Int. J. Thermo

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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.

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“…A next step in application of exergy analysis is the investigation of human body exergy balance under unsteady-state conditions [5]. Most of human body exergy analyses, mostly focused mainly on human body exergy consumption rate, have been made with the assumption of steady-state conditions of thermal environment [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. Human body exergy consumption rate determined for steady state thermal conditions will be further abbreviated Ex-st in the present paper.…”

Section: Introductionmentioning

confidence: 99%

Unsteady-state human-body exergy consumption rate and its relation to subjective assessment of dynamic thermal environments

Schweiker

Kolařík

Dovjak

et al. 2016

Energy and Buildings

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Document Version Peer reviewed version Link back to DTU Orbit Citation (APA):Schweiker, M., Kolarik, J., Dovjak, M., & Shukuya, M. (2016). Unsteady-state human-body exergy consumption rate and its relation to subjective assessment of dynamic thermal environments. Energy and Buildings, 116, 164-180. DOI: 10.1016/j.enbuild.2016. ABSTRACTFew examples studied applicability of exergy analysis on human thermal comfort. These examples relate the human-body exergy consumption rate with subjectively obtained thermal sensation votes and had been based on steady-state calculation methods. However, humans are rarely exposed to steady-state thermal environments. Therefore, the first objective of the current paper was to compare a recently introduced unsteady-state model with previously used steady-state model using data obtained under both constant and transient temperature conditions. The second objective was to explore a relationship between the human-body exergy consumption rate and subjective assessment of thermal environment represented by thermal sensation as well as to extend the investigation towards thermal acceptability votes. Comparison of steady-state and unsteady-state model showed that results from both models were comparable when applied to data from environments with constant operative temperature. In contrast, when applied to data with temperature transients the prediction of particular models differed significantly and the unsteady-state model resulted in better prediction of mean skin temperature. The results of the present study confirmed previously indicated trends that lowest human body exergy consumption rate is associated with thermal sensation close to neutrality. Moreover, higher acceptability was in general associated with lower human body exergy consumption rate.

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Exergy performance of human body under physical activities

Cited by 37 publications

References 25 publications

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

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

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

Unsteady-state human-body exergy consumption rate and its relation to subjective assessment of dynamic thermal environments

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