Physiological Responses During High Intensity Functional Training Exercise Are Affected By Skill Level

Abstract

Although high-intensity functional training (HIFT) is an increasingly popular exercise strategy, research describing the acute physiological responses are few and predominantly limited to novice or untrained. PURPOSE: To compare the cardiorespiratory responses of a bout of HIFT among individuals with varying degrees of skill. METHODS: Eighty-two participants (31.0 ± 7.4 years; 172.6 ± 9.6 cm; 77.9 ± 13.8 kg) with at least six-months of HIFT experience and varying skill levels were tested. Skill level was categorized by self-reported times of the benchmark workout “Fran” [Novice (NOV), n = 32; Intermediate (INT), n = 24; Advance (ADV), n = 26; (times reported = 5.3 ± 2.7 mins)]. All participants performed aerobic capacity testing to examine peak levels of oxygen consumption (VO2), heart rate (HR), respiratory exchange ratio (RER), and lactate (LT). A week later, similar variables were measured with averages obtained for VO2, HR, RER, and LT during a 15-minute HIFT based workout. Univariate analysis of variance (ANOVA) with Bonferroni adjustments were used to examine differences between skill category and outcome variables. RESULTS: During the Treadmill test, significant differences were only observed for VO2 (ADV = 49.53 ± 5.12 ml/kg/min; NOV = 43.83 ± 6.49 ml/kg/min; p = 0.001; η2 = 0.924) and LT (ADV = 12.31 ± 2.48 mmol/dL; NOV = 9.93 ± 3.33 mmol/dL; p = 0.004; η2 = 0.874), with ADV athletes having greater values than NOV (p < 0.05). No significant differences were observed between ADV & INT (p > 0.05). Similarly, during the HIFT workout, differences were also observed between ADV and NOV categories, but only for VO2 (ADV = 38.71 ± 3.47 ml/kg/min; NOV = 34.42 ± 5.20 ml/kg/min; p = 0.002; η2 = 0.897) and LT (ADV = 9.04 ± 1.68 mmol/dL; NOV = 9.61 ± 2.40 mmol/dL; p < 0.001; η2 = 0.946). CONCLUSION: These findings provide evidence regarding the impact skill level has on physiological outcomes. During a maximal effort bout of HIFT, the more advanced athletes tend to exhibit more efficient cardiorespiratory markers. Further research is necessary to elucidate how these differences impact overall performance of HIFT exercise.