Energy Expenditure and Intensity of Group-Based High-Intensity Functional Training: A Brief Report.

Abstract

High-intensity functional training (HIFT) may offer an attractive, time-efficient alternative to traditional aerobic exercise. However, limited information is available in the literature regarding HIFT meeting exercise guidelines for energy expenditure (improve health outcomes: ≥1000kcal/wk; weight management: ≥2000kcal/wk) and level of intensity (moderate: 3-6 metabolic equivalents [METs], vigorous: ≥6 METs) elicited by this approach. Thus, the primary aim was to objectively measure energy expenditure and intensity of HIFT sessions. \Energy expenditure was assessed in 20 adults (18-50y, 50% females). The HIFT session format included the following segments: warm-up (∼5min), exercise (∼35min), and cooldown (∼5min). Participant oxygen consumption (COSMED, L/min and mL/kg/min), heart rate (Polar RS400), and physical activity (ActiGraph GT3X+) were collected in 15-second intervals. Average kcal per minute, METs, total kcal per session, and percent maximum heart rate (HRmax) were calculated. METs ranged from 5.5 to 11.6 for the complete session (including warm-up and cooldown). Participant's HRmax was ∼80% (range: 69%-100%). Average energy expenditure was ∼485kcal per session (∼1400kcal/wk). The vigorous-intensity exercise portion (∼35min) contributed to 80% of total energy expenditure. HIFT has the potential to meet the recommendations for exercise to improve health outcomes.