The oxygen uptake efficiency slope (OUES) is a well-established substitute for maximum oxygen uptake (O2 max) in submaximal exercise effort among adolescents and adults. Few studies have analyzed the exercise capacity (EC) and OUES of children aged 4 to 6 (preschoolers)

The respiratory system (also respiratory apparatusventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies greatly, depending on the size of the organism, the environment in which it lives and its evolutionary history.

Body fat has been proved to negatively affect EC among schoolchildren. The purposes of this study were to assess the capacity of preschoolers in achieving. O2 max and evaluate the correlation of peak metabolic equivalent (peak MET) and peak oxygen consumption (peak O2) with OUES. 

Body fat and EC 

Researchers also evaluated if body fat affected EC among preschoolers. Forty-three preschoolers under the ramped Bruce protocol of treadmill exercise testing had been retrospectively studied.

The criteria for achieving (Equation is included in full-text article.) O2 max included respiratory exchange ratio (RER) >1.1, heart rate (HR) >85% of age-predicted maximum, and HR?>200 bpm.

OUES was calculated by the 75% (OUES-75) and the entire (OUES-100) duration of the testing and normalized by body surface area. Body fat was measured using vector bioelectrical impedance analysis.

The fat mass (FM) index and fat-free mass index (FFMI) were defined as FM or FFM (kg) divided by height squared (m), respectively. The mean age of the participants was 5.70?±?0.56.

A total 79% of preschoolers met at least 1 criterion, 36.84% met 2 criteria, and none met all 3 criteria for O2. OUES-75 was moderately positively correlated with peak MET (P?=?.034; Spearman's rho?=?0.324) and peak O2 (P?<.001; Spearman's rho?=?0.667).

OUES-100 was moderately to highly positively correlated with peak MET (P?<.001; Spearman's rho?=?0.592) and peak O2 (P?<.001; Spearman's rho?=?0.825). There were moderate to high positive correlations between FFMI and peak O2 (P?<.001; Spearman's rho?=?0.668), OUES-75 (P?<.001; Spearman's rho?=?0.642), and OUES-100 (P?<?.001; Spearman's rho?=?0.670).

None of the preschoolers reached all 3 criteria for (Equation is included in full-text article.)O2max. OUES-75 and OUES-100 might be indicators of peak O2 at submaximal effort. Preschoolers with higher FFMI had better EC during treadmill exercise testing.