Cardiorespiratory fitness (CRF) is important for soccer players who need to sustain intervals of high and low intensity during a match. However, there are few intermittent graded exercise testing protocols integrating high and low intensity intervals to determine CRF. PURPOSE: To evaluate a new intermittent treadmill protocol developed to test CRF (maximum oxygen consumption or VO₂max) and recovery in soccer players. METHODS: The intermittent CRF protocol consisted of multiple stages of progressively high intensity 2-min intervals interspersed with low intensity 1-min intervals. High intensity intervals were kept at 6.5 mph, with inclination starting at 2.5% with increments of 2.5% with each stage. Low intensity intervals were kept at 4 mph with no inclination. Average VO₂and heart rate (HR) were determined during the final 15 seconds of the high and low intensity interval of the last 3 stages completed by all participants. Descriptive statistics (mean, standard deviation, proportions) were obtained for all study variables. RESULTS: A group of 11 soccer players training and competing in local teams under the Puerto Rico Soccer Federation (Age= 23.0±3.7 yrs) completed the intermittent VO₂max protocol until volitional fatigue. Maximal duration during the intermittent protocol ranged from 13-19 min. Maximal values for VO₂, HR, and respiratory exchange ratio (RER) were 51.1±6.5 ml kg min, 186.6±6.6 bpm, and 1.3±0.2 respectively. In the last high intensity intervals, mean VO₂was 41.2±3.8, 44.9±4.9, and 48.6±4.5 ml kg min; and mean HR was 161.5±11.4, 171.5±9.2, and 178.1±8.6 bpm. During the last low intensity intervals, mean VO₂was 35.3±3.2 (, 37.8±4.4, and 41.6±3.5 ml kg min; and mean HR was 147.2±13.3, 159.6±12.4, and 170.5±9.7 bpm. Recovery intervals represented approximately 85% of VO₂max, and 93% of HRmax. CONCLUSIONS: The newly developed intermittent exercise protocol allowed the achievement of VO₂was while providing information about the capacity to recover between high intensity intervals, an important aspect for optimal performance during intermittent events of relatively long duration such as soccer.