You’ve probably heard various terms for different types of exercise protocol. In particular, the term HITT programming is prolific, yet, many don’t really understand what it is.
And, there’s some confusion as to how it compares to regular aerobic “steady state” protocol.
Let’s take a look at some of the scientific information as well as some “real world” application in comparing these two key types of exercise protocol:
High Intensity Interval Training (HIIT) – which involves short bouts of intense exercise interspersed with recovery periods.
Moderate Intensity Continuous Training (MICT) – which involves a sustained effort of medium intensity exercise that is not broken up by recovery periods. This is sometimes also known as steady-state exercise.
NOTE: As with any kind of big “broad brush” description, most of the information will be cast as “generalities” with the assumption that almost any protocol can be broken out and designed to be more specific to your particular circumstances, physical attributes and current conditioning.
What is HIIT?
You’ve probably already heard of HIIT (High Intensity Interval Training).
It involves short (typically less than 4-min) spurts of highly intense exercise which are separated by periods of complete rest or less-intense active recovery.
A HIIT workout protocol using a stationary bike, for example, might include :30-second intervals of high intensity (fast cadence and high resistance) spinning, each followed by 1 minute of easy (low resistance) cycling.
But, what exactly do we mean by “high intensity” exercise?
Generally speaking, HIIT intervals involve “near maximal” efforts that we perform at over 80-85% of our maximum heart rate (HRmax).
Another way of classifying the intensity of exercise is by comparing it to our body’s maximum rate of oxygen consumption (or VO2 max). High intensity intervals generally push us to over 75-80% of our VO2max.
What is MICT?
Moderate-Intensity Continuous Training (MICT)(steady state) involves a sustained effort, with no intervening rest periods.
An example may be cycling on a stationary bike continuously at a constant pace for 20 minutes.
In contrast to HIIT, MICT workouts are much less intense, with exercise performed at a moderate intensity. This typically corresponds to 55-75% of maximum heart rate (HRmax) or 40-65% of maximal oxygen consumption (VO2max).
Weight Gain During Inactivity
During the Covid-19 lockdown, you may have gained a bit of weight. And, unfortunately it wasn’t lean muscle mass!
A reduction in total daily energy expenditure (through less movement) coupled with increased energy intake (as a result of prolonged close proximity to the fridge and snacking out of boredom) will invariably lead to fat deposition and an increase in body-fat percentage.
So, what type of workout is better for burning this newly accumulated fat: HIIT or MICT?
First things first: both HIIT and MICT are shown to elicit significant reductions in total body-fat percentages. It’s an obvious point, but if you’re looking to shed fat and improve your body composition, doing any exercise (either HIIT of MICT) is better than doing nothing at all (or relying on dietary changes alone).
Both Are Good Solutions
A meta-analysis published in the British Journal of Sports Medicine (BJSM), which analyzed the data from 1,012 subjects across 36 studies, found that HIIT was associated with a 28.5% greater reduction in absolute fat mass compared to MICT.
People enrolled in HIIT programs lost 1.58 kg (3.5 lbs) of body fat on average, whereas those participating in MICT programs lost 1.13 kg (2.5 lbs)
Despite this finding, the meta-analysis found that, while both HIIT and MICT produce significant reductions in total body fat percentage, there was no significant difference between the groups.
When viewed in overall percentages, those performing HIIT dropped their body-fat percentage by 1.50% percentage points, which was similar to the 1.44% drop in those performing MICT.
Several other studies of overweight and obese subjects also report no significant difference between HIIT and MICT in terms of improving body composition.
For example, a meta-analysis published in Obesity Reviews reported a 3 cm reduction in waist circumference in both HIIT and MICT groups, with exercise programs involving 3 days per week of exercise and lasting for 10 weeks on average.
But, HIIT is the “TIME-EFFICIENCY” Winner
Interestingly, however, the evidence seems to be clear that despite similar outcomes on body composition, HIIT requires less time.
For instance, one meta-analysis of 22 studies found that MICT sessions lasted 40 minutes on average, compared to just 30 minutes for HIIT.
The BJSM meta-analysis crunched the numbers and concluded that while MICT gives you a 0.0026% reduction in body fat percentage per a minute of exercise, the equivalent figure for HIIT is 0.0050% per minute.
In other words, HIIT is a more time-efficient way of shedding fat.
There are good physiological reasons for this.
Higher intensity exercise generally stimulates greater production of hormones such as adrenaline, noradrenaline and growth hormone -- all of which promote fat-burning or fat oxidation.
Furthermore, HIIT causes more of something known as excess post-exercise oxygen consumption (EPOC). More commonly referred to as “afterburn,” EPOC occurs during recovery after exercise when oxygen consumption is elevated above baselineresting levels as the body restores various metabolic processes back to normal.
Such processes include the removal of lactate and H+ ions, rebuilding muscle glycogen stores and oxidation of fat for fuel for a longer period of time.
All in all, then, if you’ve only got a limited opportunity for exercise, say 30 minutes, and burning fat is your top priority, then HIIT represents a much better investment of your time.
Bear in mind, however, that by virtue of including high intensity, near-maximal efforts, HIIT workouts place more stress on your body.
As such, the risk of injury is higher and you may require greater recovery time between HIIT workouts.
HIIT or STEADY STATE - CONSULT A TRAINER
Regardless of whether you prefer HIIT or MICT (steady state), it is worth hiring a trainer to be certain that you are moving in a safe and effective way.
Taking the time to learn proper exercise technique can improve your results and help prevent injuries.
Plus, you’re unique. Your body’s physical attributes, current conditioning, body mechanics, experience, and goals are unique to YOU.
As a fitness professional, I can create a plan that is specific to you -- and your requirements. With a program that fits, you are much more likely to achieve the results you seek.