Shane S. Robinson, Jason C. Casey. University of North Georgia, Oakwood, GA.

BACKGROUND: High Intensity Functional Training (HIFT) is a successful mode of exercise that uses constantly varied functional movements that are executed at a high intensity. However, there is limited research examining HIFT, including the physiological responses to the modality. Therefore, the purpose of this study was to assess the physiological responses elicited from two differing HIFT workouts. METHODS: Five (n = 5) males with a HIFT training history of a minimum of three times per week for the previous six months completed this study. After the familiarization trial, each participant completed a crossover study where all participants completed a seven-minute workout of maximal burpees (W1), and an eight-minute workout of box jumps and deadlifts (W2) during two separate experimental trials. The following variables were collected during each trial: continuous oxygen consumption, continuous heart rate, rating of perceived exertion, five-minute post blood lactate, and caloric expenditure. Mean differences were statistically compared between the two workouts via a paired samples t-test with a level of significance set to α = 0.05. RESULTS: Average (W1: 38.5 ± 5.1, W2: 34.6 ± 6.7 mL/kg/min; p = 0.02) and maximum (W1: 49.6 ± 7.5, W2: 46.8 ± 8.3 mL/kg/min; p = 0.01) oxygen consumption were significantly greater in W1 compared to W2. There were no significant differences in average heart rate (W1: 175 ± 7, W2: 175 ± 8 BPM; p = 0.17), max heart rate (W1: 191 ± 4, W2: 187 ± 5 BPM; p = 0.28), rating of perceived exertion (W1: 16 ± 1, W2: 16 ± 1; p = 0.39), five-minute post blood lactate (W1: 13.2 ± 2.5, W2: 13 ± 2.6 mmol/L; p = 0.47), or caloric expenditure (W1: 208 ± 16, W2: 211 ± 20 Kcals; p = 0.23). CONCLUSIONS: This study indicated that W1 elicited a statistically significantly higher average and maximal oxygen consumption compared to W2. However, there were no significant differences for any other variable. The results of this study add to the current understanding of the physiological responses to varying HIFT modalities and can be valuable to those working with HIFT participants to optimally prescribe the modality to aid in both health and performance related improvements.

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