Methods for assessing body composition, cardiovascular and metabolic function in children and adolescents: Implications for exercise studies

PURPOSE OF REVIEW: To critically evaluate the most recent literature on the methods used to assess body composition, cardiovascular and metabolic function in children and adolescents. RECENT FINDINGS: Although regional body composition can be fairly accurately calculated by dual-energy X-ray absorptiometry, the accuracy of noninvasive estimations of visceral adipose tissue is questionable. Regarding the cardiovascular and metabolic adaptations, there is no doubt that direct and invasive methods provide high accuracy and reproducibility. For instance, exercise until exhaustion, direct Fick equation, nuclear magnetic resonance and magnetic resonance imaging are valid methods to determine maximum oxygen uptake, cardiac output and tissue substrate metabolism, respectively. Except for the direct Fick equation, all have been successfully used in pediatric studies. Relatively new techniques for the assessment of exercise training-induced adaptations in youths include the thoracic bioimpedance and the Modelflow method for cardiac output determination, and magnetic resonance spectroscopy for intramuscular and intrahepatic lipid content. Additional validation and reliability studies in pediatric populations are needed for some of these techniques (e.g. the Modelflow method). SUMMARY: Most of the techniques used in adults appear not directly applicable to youths. A combination of techniques and/or the application of new, promising and easy to use ones, such as near-infrared spectroscopy and Laser Doppler flowmetry, may advance our knowledge in pediatric exercise science.