How does obesity affect bioenergetics in human respiratory muscles?

Abstract

Obesity prevalence is increasing worldwide, and it causes restrictions in the respiratory system. Bioenergetics is known as energy management in a living cell. Respiratory muscle can be considered a thermodynamic machine that converts chemical energy into mechanical work during each breathing cycle. This research aimed to reveal glucose consumption, exergy destruction, and entropy generation in healthy, obese, and obesity hypoventilation syndrome (OHS) patients using thermodynamic analysis of the work of breathing. A human respiratory system was modeled thermodynamically for healthy, obese, and OHS patients. The systems were analyzed by applying the first and second laws of thermodynamics. Our simulations show that obese and OHS patients consume approximately 5 and 8 times more glucose, respectively, than their healthy counterparts: 0.2 mmol/min for healthy, 1.06 mmol/min for obese, and 1.59 mmol/min for OHS. Exergy destruction values for the healthy, obese, and OHS models were calculated as 6.41 × 10−3 (kJ/min), 4.85 × 10−2 (kJ/min), and 6.16 × 10−2 (kJ/min), respectively. Entropy generation values of the healthy, obese, and OHS models throughout the breathing cycle were 2.15 × 10−5 (kJ/K)/min, 1.63 × 10−4 (kJ/K)/min, and 2.07 × 10−4 (kJ/K)/min, respectively. Thermodynamic balances and calculations were performed to simulate the bioenergetic changes happening during breathing. The obese and OHS models had significantly increased glucose consumption, exergy destruction, and entropy generation than the healthy model. The results point to the fact that respiratory performance is associated with obesity and excessive food consumption damages the respiratory system.