Effects of obesity on the oxygen cost of breathing in children

Area of Science:

• Pediatric Physiology
• Obesity Research
• Respiratory Metabolism

Background:

• Obesity in children is a growing concern impacting metabolic health.
• Understanding the physiological costs of breathing in obese children is crucial for assessing exercise capacity.
• The eucapnic voluntary hyperpnea (EVH) technique is a validated method for measuring the oxygen cost of breathing.

Purpose of the Study:

• To investigate the impact of obesity on the oxygen (O2) cost of breathing in 10- and 11-year-old children.
• To compare resting and exercise-induced oxygen uptake (V˙O2) between children with and without obesity.
• To determine if increased chest mass in obese children contributes to altered respiratory metabolic costs.

Main Methods:

• Seventeen children (8 without obesity, 9 with obesity) participated.
• Eucapnic voluntary hyperpnea (EVH) trials were conducted at two ventilation levels.
• Oxygen cost of breathing was assessed by the slope of oxygen uptake (V˙O2) versus minute ventilation.
• Dual-energy X-ray absorptiometry (DXA) was used to measure body composition, including chest mass.

Main Results:

• Resting and EVH V˙O2 were significantly higher in children with obesity compared to those without (P = 0.0096).
• The oxygen cost of breathing (slope) did not differ significantly between groups (P = 0.99).
• However, the intercept of the V˙O2 versus ventilation relationship was significantly greater in children with obesity.
• Chest mass accounted for 85% of the variance in resting V˙O2 among obese children.

Conclusions:

• Obesity in children is associated with higher absolute resting and ventilatory metabolic costs.
• Increased chest mass in obese children contributes significantly to elevated resting energy expenditure.
• Despite higher absolute costs, the relative efficiency of the respiratory muscles (oxygen cost of breathing) is maintained in pediatric obesity.