(5) EFFECT OF HIGH-INTENSITY FUNCTIONAL TRAINING WITH A RESPIRATORY MUSCLE TRAINING DEVICE ON VO2MAX, ANAEROBIC POWER, AND PERFORMANCE

Purpose: Respiratory muscle fatigue can limit high-intensity performance. Respiratory muscle training (RMT) devices increase breathing resistance during exercise and recovery, potentially enhancing adaptation due to additional stress. Therefore, we aimed to determine the effect of high-intensity functional training (HIFT) with a RMT device on aerobic capacity, anaerobic capacity, and performance on a maximal fitness test. Methods: Twenty-six recreationally active adults (age=22.4±1.9y, BMI=23.8±3.0kg/m²) were randomized into two groups with (RMT; M=7, F=6) and without (CON; M=6, F=7) a RMT device. Training consisted of three 30-minute HIFT sessions per week for six weeks. Each session consisted of four rounds of six HIFT exercises using a 30:30-second work-to-rest ratio, with 2.5 minutes of rest between rounds. Pre- and post-testing was conducted on three separate days over one week and consisted of a graded VO_2max test on a cycle ergometer, 30-s Wingate test, and an 18-minute self-paced maximal HIFT bodyweight (max HIFT) test with each round containing 10 inverted rows, 5 pushups, and 15 squats. Following testing, VO_2max, mean power (MP), peak power (PP), rate of fatigue (RoF), and number of rounds completed (RC) were reported. Ratings of perceived exertion (RPE) and blood lactate (BLa) were collected before and after the max HIFT test. Change scores (Δ) were calculated by subtracting pre values from post values for each variable. RM ANOVAs were used to assess the effects of the intervention on VO_2max, MP, PP, RoF, RC, RPE, and ΔBLa (α=0.05). RM ANCOVAs using baseline VO_2max as the covariate were also used to assess the effects of the intervention while accounting for differences in baseline aerobic capacity for each variable (α=0.05). Effect sizes (ES) were also calculated. Results: The RM ANOVAs revealed a time main effect for VO_2max (p=0.001, ES=0.72), RC (p< 0.001, ES=1.9) and ΔBLa (p=0.002, ES=-0.66), but not MP (p=0.092, ES=0.35), PP (p >0.05, ES=0.006), RoF (p >0.05, ES=-0.26), or RPE (p >0.05, ES=-0.13). However, after accounting for baseline VO_2max, there were no longer time main effects for RC (p=0.070, ES=0.136) or ΔBLa (p >0.05, ES=0.005). There were no group main effects or interactions on any variable (p >0.05). Conclusions: HIFT improved aerobic capacity and performance on the max HIFT test with enhanced exercise-specific buffering capacity as indicated by an attenuated increase in BLa despite greater performance on the max HIFT test but did not affect anaerobic power. Importantly, there was no apparent benefit of HIFT with the RMT device. The lack of improvement in RC after accounting for baseline fitness suggests improvements were driven by less fit individuals in the cohort and that HIFT may provide a greater benefit to those with lower baseline fitness. Future studies should explore the effects of using a RMT device during dedicated respiratory muscle training to more specifically target improvements in respiratory muscle function. Practical Applications: HIFT improved aerobic capacity, buffering capacity, and exercise-specific performance. However, HIFT did not improve anaerobic power and the use of a RMT device did not provide any additional benefit to performance. These findings suggest that HIFT can be an effective training method for improving fitness, particularly for individuals with lower baseline fitness. The impact of targeted respiratory muscle training with a RMT device remains to be determined. Acknowledgements: This project was funded by a grant from NEO-Ventures LLC. This abstract was made possible in part by Grant Number T32-GM081740 from NIH-NIGMS for GFM. Its contents are solely the responsibility of the authors and do not represent the official views of NEO-Ventures LLC nor NIGMS or NIH.