Reliability of aerobic fitness in combat sports: Insights from the ITStriker app specific incremental test

Physical assessment of physiological variables and load control in combat sports athletes is crucial for tailoring individualized training programs. However, most tests are not modality-specific, and further evidence is needed to assess variability in results and establish a reliable measure of kicking performance. Thus, this study aims to assess the reproducibility and consistency of VO2max, anaerobic threshold (AT), and external load parameters in kicking performance using the ITstriker app, a mobile and easy-to-use tool designed for contact combat sports practitioners. For that, a total of 11 contact combat sports athletes (age: 22.5 ± 5.4 years, body mass: 72.2 ± 15.7 kg, height: 169.6 ± 7.4 cm, experience: 7.9 ± 6.1 years, body fat: 14.2 ± 3.2%) participated in a test-retest protocol. Participants completed two lab visits under standardized conditions, including controlled food consumption and testing at the same time of day. The ITstriker app automatically generated data on VO2max, AT, maximum heart rate (HRmax), strike frequency metrics (SFmax and SFat), time to exhaustion (TTE), and total strikes (ST). Results demonstrate that the ITstriker app reliably (ICC > 0.8) measures aerobic power metrics (VO2max and HRmax) and pacing variables (SFmax and SFat), demonstrating consistent values through a low variability result (coefficient of variations <10%). In contrast, the AT indicator showed limited reproducibility (ICC < 0.4). In conclusion, the ITstriker app offers a reproducible, low-cost tool for assessing physiological markers and training prescription based on strike frequency (pacing), but caution is advised when interpreting AT data.