Ability of preschoolers to achieve maximal exercise and its correlation with oxygen uptake efficiency slope ∼ an observational study by direct cardiopulmonary exercise testing

Abstract

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). 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. We 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 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 (m2), respectively.The mean age of the participants was 5.70 ± 0.56. Seventy-nine percent 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 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.

Comparison of cardiorespiratory fitness between preschool children with normal and excess body adipose ~ An observational study

“…In our study, we observed that even in preschool children with normal body adipose, there was around 20% (no matter by which classifications) participants could not reach maximal effort during exercise testing. Few studies in children aged less than 7 years old had proved that they had poorer ability to perform maximal effort as similar as out results[19, 39]. What is more, we also found that preschool children with excess body adipose had significant lower percentage to achieve maximal effort than those with normal body adipose by BMI and FFMI classifications.…”

“…OUES-100 has been proved to correlate strongly with peak O 2 in healthy children aged more than seven years old[41]. It our past study, we found that OUES correlated positive-moderately with peak MET and peak VO2 in preschool children older than 4 years old[19]. Many studies had shown that health-related physical fitness is associated with total and central body fat among preschoolers[18, 42] but little available studies assessed preschoolers’ CRF by CPET.…”

“…For comparisons of CRF between preschoolers with excess and normal body adipose under different classifications, the minimum sample size was 64 in preschoolers with normal adipose group and 16 in preschoolers with excessive adipose group with type 1 error = 0.05, power = 0.8, large effect size, and allocation ratio = 4 (based on a nationwide survey by Ministry of Education of Taiwan in 2003[3]). The mean (M) and standard deviation (SD) for effect size estimation were based on the study we conducted before in preschool children[19]. The CPET data and the reports of EKG and echocardiography of the included participants were reviewed by K-L LIN (who has experience in CPET for more than 15 years) and S-H Tuan (who has experience in CPET for more than 5 years), respectively.…”

“…The oxygen uptake efficiency slope (OUES) estimates the ventilatory efficiency with respect to oxygen consumption (VO 2 ) [21]. It is now a well-established substitute for maximal VO 2 (VO 2 max)in submaximal exercise effort among adults and older children[22], and our study proved that it could be also used in preschool children[19] since they may not be able to sustain activity to maximal level during CPET. To our knowledge, no available studies evaluate the association between excess body adipose, defined by BMI, FMI, or FFMI, and the CRF indicated by OUES or maximal VO 2 during CPET, among preschool children.…”

“…However, BMI reflects both the fat mass (FM) and the fat-free mass (FFM) in the body, which may have different associations with physical fitness[16], and it had been proved to correlate poorly with % fat mass (%FM) in a preschool population[17]. Based on currently presented few studies, FM index (FMI) and FFM index (FFMI) might be better than BMI in reflecting the relationship between body adipose and CRF in preschool children[18, 19].…”