High Intensity Functional Training in Hybrid Competitions: A Scoping Review of Performance Models and Physiological...

High-Intensity Functional Training (HIFT) is a training method that has garnered increasing attention due to the rise in hybrid competitions such as CrossFit or Hyrox, a race format combining strength and endurance tasks in a fixed structure. Therefore, an integrative approach is needed to help us understand which physiological capacities this training method enhances. Objectives: This scoping review aimed to map the current scientific literature related to HIFT, with a particular focus on physiological and psychobiological determinants of performance in hybrid competition contexts. Methods: Following the methodological framework of Arksey and O'Malley and the PRISMA-ScR guidelines, a systematic search was conducted in Web of Science, Scopus, and PubMed. Thirty-nine studies published between 2015 and 2025 were included. Results: HIFT was found to improve key physical attributes such as aerobic capacity, muscular strength, anaerobic power, and fatigue tolerance. Increases in VO₂max ranging from 8% to 15% and strength gains of 10% to 20% in major lifts were commonly reported. Improvements in local muscular endurance, power output, and recovery capacity were also observed. The physiological benefits appeared more pronounced in trained individuals, especially those with greater resistance training volume. In addition, psychobiological responses, including perceived exertion, cognitive control, and motivation, were explored in several studies, with more experienced athletes showing higher fatigue tolerance and better performance consistency under stress. Conclusions: HIFT enhances essential physical attributes applicable to hybrid events. The findings support the use of HIFT as a foundational method for training athletes involved in demanding multi-domain fitness settings, without attributing these benefits specifically to any single competitive event.