Validity, Reliability, and Sensitivity of the Brazilian Jiu-Jitsu Cardiorespiratory Fitness Test: A Methodological Approach Based on Combat Specificity

Brazilian jiu-jitsu (BJJ) is a combat sport that requires intermittent high-intensity actions, strong technical skills, strength, and aerobic capacity. Yet, there is limited evidence of validated sport-specific field protocols. This study aimed to determine the validity, reliability, and sensitivity of the BJJ Cardiorespiratory Fitness Test (BJJ-CRFT). Twenty-three trained practitioners (20 men and 3 women; age 34.4 ± 7.6 years) performed a cardiopulmonary exercise test on a treadmill and completed the BJJ-CRFT on two occasions, one week apart. Construct validity was examined using receiver operating characteristic (ROC) analysis, while concurrent validity was tested against maximal oxygen uptake (VO2max) and maximal aerobic speed (MAS). Intra-session reliability was determined through the intraclass correlation coefficient (ICC) and the coefficient of variation (CV%). Main results showed a good discriminative ability (ROC: 0.82; 95% CI: 0.64–0.99, p = 0.001). Total repetitions in the BJJ-CRFT showed a large positive correlation with VO2max (r = 0.66; 95% CI: 0.35–0.85, p = 0.0006) and a very large positive correlation with MAS (r = 0.72; 95% CI: 0.44–0.87, p = 0.0001). Key performance metrics, including guard passes and test duration, demonstrated excellent relative reliability (ICC = 0.99) and good absolute reliability (CV% = 4.4% and 3.6%), being sensitive to small changes. These results confirm that the BJJ-CRFT is a valid, reliable, and sensitive field test for monitoring aerobic adaptations and guiding training prescription in BJJ.