Can anthropometry and physical fitness testing explain physical activity levels in children and adolescents with obesity?

Objectives: As time with patients and resources are increasingly limited, it is important to determine if clinical tests can provide further insight into real-world behaviors linked to clinical outcomes. The purpose of this study was to determine which aspects of anthropometry and physical fitness testing are associated with physical activity (PA) levels among youth with obesity. Design: Cross-sectional study. Method: Anthropometry [height, waist circumference, bodyweight, fat percentage], physical fitness [muscular endurance (partial curl-ups), flexibility (sit-and-reach), lower-body power (long-jump), upper-body strength (grip), speed/agility (5 x 5-m shuttle), cardiorespiratory fitness (VO2-max)], and PA [light (LPA), moderate (MPA), vigorous (VPA), MVPA] was assessed in 203 youth with obesity. Results: The sample was stratified by age <12 yrs (children); 12 yrs (adolescents) and sex. Stepwise regression evaluated associations between PA with anthropometry and physical fitness. Children (57% male) and adolescents (45% male) had a BMI Z-score of 3.5( SD:0.94) and 3.1( SD:0.76) respectively. Long-jump explained 19.5% [(Standardized) Beta = 0.44; p = 0.001] of variance in VPA for childhood girls and 12.6% (Beta = 0.35; p= 0.025) of variance in MPA for adolescent boys. 5 x 5-m shuttle explained 8.4% (Beta = -0.29; p= 0.042) of variance in MVPA for childhood girls. Body mass explained 6.3% (Beta = -0.25; p = 0.007) of variance in LPA in childhood boys. Fat percentage explained 9.8% (Beta = 0.31; p = 0.03) of variance in MPA in adolescent girls. Conclusions: In conclusion, tests of lower body power, body mass and fat percentage provide limited information concerning PA levels in youth with obesity. Activity monitoring should be considered in addition to clinical assessments to more fully understand youth health. (C) 2020 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.