High-Intensity Functional Training (HIFT): Definition and Research Implications for Improved Fitness

Abstract

High-intensity functional training (HIFT) is an exercise modality that emphasizes functional, multi-joint movements that can be modified to any fitness level and elicit greater muscle recruitment than more traditional exercise. As a relatively new training modality, HIFT is often compared to high-intensity interval training (HIIT), yet the two are distinct. HIIT exercise is characterized by relatively short bursts of repeated vigorous activity, interspersed by periods of rest or low-intensity exercise for recovery, while HIFT utilizes constantly varied functional exercises and various activity durations that may or may not incorporate rest. Over the last decade, studies evaluating the effectiveness of HIIT programs have documented improvements in metabolic and cardiorespiratory adaptations; however, less is known about the effects of HIFT. The purpose of this manuscript is to provide a working definition of HIFT and review the available literature regarding its use to improve metabolic and cardiorespiratory adaptations in strength and conditioning programs among various populations. Additionally, we aim to create a definition that is used in future publications to evaluate more effectively the future impact of this type of training on health and fitness outcomes.

Physiological differences between advanced CrossFit athletes, recreational CrossFit participants, and physically-active adults

“…CrossFit1 (CF) is a form of high-intensity functional training that combines resistance exercises, gymnastics, and traditional aerobic modalities (e.g., cycling, rowing, running) into single workouts that vary by day to elicit general physical preparedness [1,2]. This training form is enjoyed recreationally by participants of varying levels of fitness, training experience, age, and lifestyles [3] and also exists as its own sport.…”

Acute Caffeine Supplementation Does Not Improve Performance in Trained CrossFit® Athletes

“…The recent dramatic increase in high-intensity functional training-which aims to enhance multiple domains of physical fitness by temporally exposing athletes to varying modes of exercise (e.g., endurance and resistance) within and between each session, for varying durations (e.g., 2-60 min), at a relatively high-intensity [22]-has been primarily driven by CrossFit ® , which has an annual competition called the CrossFit ® Games [22][23][24][25][26]. Within the athletic performance environment of CrossFit ® , repetitions can approach up to 700 in a 20-min training session [25,27].…”

Can High-Intensity Functional Suspension Training over Eight Weeks Improve Resting Blood Pressure and Quality of Life in Young Adults? A Randomized Controlled Trial

“…Although initially developed in the context of endurance training, the application of "20 seconds loading-10 seconds resting" protocols in strength training also revealed positive effects [19,20]. High-intensity functional training (Functional HIIT ) is described as a form of exercise including functional, multi-joint movements performed in repeated bouts with high intensities and short intervals of recovery [21,22]. Exercise programs with repeated high-intensity intervals aiming to enhance cardiovascular, metabolic, and psychological health are increasingly applied and analyzed in sport and exercise science [22][23][24][25].…”