Workout Duration Alters the Importance of Predictive Traits on High-Intensity Functional Training Workout Performance

Relevant skills and physiological traits vary between high-intensity functional training (HIFT) workouts, but it is unknown how altering each programming detail affects their importance. To examine the effect of workout duration on relationships to HIFT performance, twelve men and ten women with ≥2 years of HIFT experience (29.3 ± 7.1 years, 171 ± 7 cm, 80.5 ± 15.6 kg) completed a baseline visit to assess body composition and performance in vertical jump, barbell thruster, and 2000 m rowing tests. Participants returned twice to randomly complete the same circuit of rowing, barbell thrusters, and box jumps for "as many repetitions as possible" in 5 or 15 min. Performance was described by expressed kinetics on each exercise, overall and individual exercises, repetition completion rates and volume load completed, and transition times. Spearman correlation analysis revealed several expected relationships (p < 0.05) but also differences between workout durations. Performance measures, especially rowing (time: ρ = -0.89 to -0.94; power: ρ = 0.88 to 0.93), were more applicable to the 5 min workout. Experience and body composition measures (ρ = -0.47 to -0.50) were more often related to the 15 min transition strategy. These data suggest that increasing workout duration alters the importance of relevant predictive traits.