The purpose of this study was to compare the exercise and recovery muscle oxygenation response of Women and Girls during two 30s Wingate anaerobic tests separated by two minutes of active cycling recovery (resistance ≈ 2.5% body weight, 60-80rpm). Oxygenated hemoglobin (HbO2), deoxygenated hemoglobin (HHb), total hemoglobin (tHb), and tissue saturation index (TSI) were monitored at the right vastus lateralis muscle using near infrared spectroscopy (NIRS) throughout exercise, recovery, and a post-exercise femoral artery occlusion to TSI plateau. Pressure was preset at 250mmHg for Women and 210mmHg for Girls, achieved by rapid inflation in 0.3 seconds, and maintained until a 2 minute TSI plateau occurred or 10 minutes had passed. Twenty Women (23.8[2.12] years) and 13 Girls (9[1] years, combined Tanner stage <4) completed all tasks excepting 1 girl who did not complete occlusion. Significant group, time, and group by time interaction effects were observed for peak and mean power (Watts.kgFFM-1). Women had significantly greater power output compared to Girls for both Wingates. While both groups had reduced power output in Wingate 2, the reduction was significantly greater in Women compared to Girls. No significant group differences were found for resting TSI, recovery TSI, minimum TSI during either Wingate test, or for minimum TSI during occlusion, however a time main effect for Women was observed with minimum TSI being significantly lower in Wingate 1 compared to Wingate 2. Girls had similar minimum TSI for both Wingate tests. Women also demonstrated a significantly greater difference between Wingate minimum TSI and occlusion minimum TSI in Wingate 2 compared to Wingate 1. During Wingate 1, HHb increase was greater in Girls compared to Women and remained elevated during recovery compared to women. Changes in HbO2, HHb, and tHb were reduced in Wingate 2 for both groups, more so in Women for tHb and in Girls for HHb. Recovery was not different between groups with the exception of a faster TSI time constant of recovery in Women (τ =20.25 [13.01]s) compared to Girls (τ =36.77 [13.38]s) which is attributed to a faster HHb time constant in Women (τ =13.6 [0.44]s) compared to Girls (τ =30.77[19.47]s). Both groups demonstrated similar power output results and TSI response across the two Wingate tests but Girls were better able to repeat the anaerobic performance with a consistent TSI minimum between the two tests despite a faster recovery of HHb and TSI in women. These findings, in the context of observed Hb variable differences between groups, provide evidence of greater oxidative metabolism in Girls during a high intensity exercise. / Graduate / December 18, 2016