(27) RELATIVE PACING OF A HIGH-INTENSITY FUNCTIONAL TRAINING WORKOUT DOES NOT AGREE WITH TRADITIONAL INTENSITY DESCRIPTORS OF HEART RATE, RPE, AND LACTATE

Purpose: High-Intensity Functional Training (HIFT) combines resistance training, gymnastics, and traditional aerobic exercises into single workouts, and each quantifies intensity differently. Traditional resistance training bases intensity on relative strength, gymnastics off complexity, and aerobic exercise uses pace or physiological responses (e.g., relative heart rate [HR], lactate). With no established approach, existing HIFT research has tried using HR, lactate, and ratings of perceived exertion (RPE) to quantify intensity, but these often look the same across most workouts. Since the most common objective is to complete work as fast as possible, relative pacing (e.g., average pace divided by maximal pace) may provide a more accurate and relevant description of HIFT intensity. This study examined the agreement between relative pacing and traditional physiological markers of intensity in HIFT. Methods: Recreationally trained adults (n = 19) completed 5-round HIFT circuits that included power cleans, toes-to-bar, and wall balls programmed at high- (HV, 10 – 15 – 20 repetitions, 225 total repetitions) and low-volume (LV, 5 – 10 – 15 repetitions, 150 total repetitions) repetition schemes. Pre-exercise HR, lactate, and RPE were collected before participants warmed up, and these were repeated immediately post-exercise. Relative HR was calculated as a percentage of age-predicted maximum (220 – Age). Post-exercise blood lactate and RPE were examined as percent changes from pre-exercise. During warm-ups, participants completed 5 repetitions of each exercise, as well as a single workout round, as fast as possible to determine maximal speed in each. Video recordings of each workout were analyzed to determine repetition completion rates of each exercise and round, and each was divided by their respective maximal speeds to calculate relative pace. Pearson correlation coefficients (r) were calculated between relative pacing and traditional intensity metrics, and then agreement was evaluated by Bland Altman plots of the averages and differences of each intensity metric, their correlation, and a coefficient of variation (CV). Results: Aside from the relationship between RPE and HV power clean pace (r = 0.995, p < 0.001), there were no significant correlations observed between variables. Likewise, agreement analysis only showed acceptable agreement between HR and relative round pace (mean bias = 45.9%, r = 0.27, p = 0.266, CV = 21.5%). Otherwise, mean biases mostly exceeded 600% with significant (p < 0.001) correlations between the averages and differences of each paired intensity comparison. Conclusions: Traditional physiological (HR and lactate) and subjective (RPE) metrics of intensity and relative pacing were not related or in agreement. Though a scientific foundation supports the use of each metric, these data suggest they do not all describe the same aspect of HIFT workout intensity. Practical Applications: Existing metrics (HR, lactate, and RPE) are known to lack precision when describing HIFT intensity and, in the case of lactate, are impractical within a common gym setting. Moreover, the present data indicates that these metrics are not quantifying the same thing as relative pacing. Since completion speed is key to HIFT performance, pacing-based monitoring may offer a more precise way to assess workout difficulty and optimize programming. Acknowledgements: None