High Intensity Functional Training – a new label for an old form of training?

Recently, a group of researchers (Feito et al. 2018) have made a call to label and define high intensity functional training or “HIFT” a type of exercise training that consists of functional, multi-joint movements incorporated into either aerobic or resistance based training to improve general fitness (Feito et al. 2018; Heinrich 2015). I find it interesting that these researchers are attempting to separate this form of exercise training from High Intensity Interval Training or HIIT. Recall, the working definition of HIIT is any form of exercise training that involves short bursts of higher intensity (but NOT maximal), separated by periods of rest.

The first question that needs to be asked is: how is HIFT really different from HIIT? Given the similarity of terms and that most types of functionally based HIIT training alternates periods of work with periods of rest, do we really need to create a new term for this style of training? The authors believe so, and go on to make the case for why we should consider separating these terms.

Lets have a look at their proposition in detail, starting with a definition of functional training, given this is the central component to this style of exercise training. According to Feito and others, “Functional training or functional exercises are characterised by whole body movements which contain universal motor recruitment patterns that  occur in multiple planes of motion” including compound lifts such as squats and deadlifts, Olympic lifts such as cleans and snatches, bodyweight exercises and plyometric exercises. This is a broad definition that essential translates into any exercise not performed on a machine. However other researchers have strongly argued that even machine based exercise can be highly functional, depending on what outcome you are measuring.

A much clearer definition emerges later in the article when the authors further clarify that HIFT may be better understood using the cross-fit definition of exercise, which is any session that contains a variety of modalities that include standard cardio based training (running, rowing) body weight movements (push ups) weightlifting derivatives and gymnastics. Again at this point I am still asking how this is different to HIIT, if all that might separate the two is exercise selection. Here it gets a little more detailed, as another interesting distinction is raised. HIFT, due to its different training methodologies, may result in different physiological responses and adaptations. That’s a BIG call! During a HIFT workout, the construction of the actual workout is quite similar if not exactly an old fashion circuit, but the authors here state that when functional exercises are put together in this manner, these exercise become a more potent stimulus for improving strength, power and cardiovascular fitness. Some research is then quoted that compares the effect of HIFT versus some standard exercise programs, including one HIIT study, and reported both appear equally affective for improving cardiovascular fitness, but only the HIFT was able to improve measures of strength and power – well that should be expected if one training program includes strength and power type exercises and the other does not. Not convinced yet, but still open to changing my mind. Further cross-fit style studies are then reviewed, one containing an “AMRAP” format versus a more old fashion circuit style program and found the AMRAP workout produces much higher heart rates (90% of Max HR). This appears to suggest, that circuit formatting may make a difference to intensity, some cross-fit formats may be more fatiguing than others, an important point to keep in mind.

In the end, the authors redefine HIFT and point out, that  the actual goal of a HIFT program is to improve general parameters of fitness and performance. Enough research in this article is discussed, that shows HIFT has potent health and fitness benefits when compared to more conventional exercise training and standard HIIT routines. However, to truly create a new definition of training, the following questions still need to be answered:

1. What is Optimal format? Given there is so many different cross-fit style workouts, which one is most beneficial say for a health benefit versus a fitness benefit?
2. How hard? What is the target intensity when prescribing the work intervals, how do we know what is hard enough to elicit an effect, and equally how hard might be too hard?
3. How often? What is the optimal frequency for HIFT workouts? How many times a week can we safely tolerate this sort of training?
4. Gender and Age differences? Do HIFT have the same affect on men versus women and also older versus younger individuals
5. Do we need to incorporate periodisation? For longer term planning, what might be the most optimal way to structure a long term HIFT plan to avoid injury, training monotony and general wellbeing?

Overall, I believe the authors of this study have made a good start creating a new possible definition for a type of functional training that aims to improve general fitness and performance, given its particularly relevant to many of the FTI courses, we should watch this space for further developments. For the rest of this months articles, I will be reviewing some more HIFT studies to help us all gain a greater understanding on just what it is we are doing to our clients when they undertake this form of exercise training.

References:

Heinrich, K.M.; Becker, C.; Carlisle, T.; Gilmore, K.; Hauser, J.; Frye, J.; Harms, C.A. High-intensity functional

training improves functional movement and body composition among cancer survivors: A pilot study.

Eur. J. Cancer Care 2015, 24, 812–817.