Determination of the anaerobic threshold using near infrared spectroscopy in children that vary in peak aerobic fitness

This study compared the anaerobic threshold (%V˙O 2peak) determined by ventilatory breakpoint and near infrared spectroscopy methodology in 8--12 year old children who differed in aerobic fitness level. The subject sample was comprised of 40 male and female children between the ages of 8--12 years. The investigation employed a cross-sectional single observation design in which each subject undertook one progressive multi-stage test. The test was used to: (a) determine the ventilatory breakpoint and maximal aerobic power (VO2max) during cycle ergometry, and (b) record NIRS measurements from the right vastus lateralis muscle during exercise. The NIRS measurements to determine muscle oxygenation levels were continuously recorded during the exercise test using a commercial device (Run Man, NIM, Inc., PA). The anaerobic threshold determined by NIRS was assessed by visual inspection as the point oxygen saturation started its major decrease. Data were analyzed using a three-factor (gender x fitness x method). The % V˙O2peak equivalent to the anaerobic threshold did not differ between the method of determination (p = 0.98). The anaerobic threshold occurred at 68.5 % V˙O2peak for the Average group and 67.5% V˙O2peak for the Above Average group when determined by the Vpt. The anaerobic threshold occurred at 67.5% V˙O2peak for the Average group and 70.5% V˙O2peak for the Above Average group when determined by NIRS methodology. The anaerobic threshold did not differ between fitness level. The results of this study suggest that NIRS methodology is a physiologically valid procedure to determine the anaerobic threshold in young female and male children.