Which type of aerobic exercise is superior? High-intensity interval training (HIIT) or moderate-intensity continuous training (MICT)? Time to bust another myth!
One of the recurring advice of gurus everywhere is that high-intensity interval training (HIIT) is superior in fat loss and lean body mass maintenance than continuous moderate-intensity training (MICT). Let's bust this myth too!
WHAT IS HIIT
Interval or intermittent training, or interval training (IT), is usually operationally defined as exercise performed over several periods of short duration, interspersed with periods of recovery either at lower intensities of effort or as complete rest.
Interval training is often subcategorised as high-intensity interval training (HIIT), which is usually operationally defined as high-intensity effort exercise (>80% of maximal heart rate or aerobic capacity), while its other characteristics are the same as interval training (IT).
There is also sprint interval training (SIT), which is usually operationally defined as maximal effort training (all-out sprint), while its other characteristics are the same as interval training (IT).
WHAT IS MICT
Moderate intensity continuous training (MICT) is operationally defined as exercise of moderate effort (<80% of maximal heart rate or aerobic capacity) performed in a single period of relatively long duration.
THE DATA
Although both MICT and IT show efficacy in improving body composition, there is controversy as to whether one strategy is superior to the other.
Therefore, this recent meta-analysis attempted to look at the current literature to clarify the situation.
FAT LOSS
There is a hypothesis that interval training may offer superior fat loss benefits compared to MICT. Despite the various mechanistic hypotheses, the results of the meta-analysis did not find any superiority of IT/HIIT/SIT.
Compared to the non-exercising control groups, the groups exercising with IT and MICT had small decreases in fat mass, with little difference between them.
Data based on an earlier study suggest that IT, HIIT and SIT can produce greater reductions in abdominal fat loss compared to MICT. However, the findings of this meta-analysis contradict this claim, demonstrating similar changes in abdominal fat loss.
Besides, as we have pointed out in older articles, it is doubtful whether local fat loss is feasible.
BENEFITS TO MUSCLE MASS
In complete agreement with a previous meta-analysis, which refuted the claim that aerobic exercise can produce increases in muscle mass similar to those of anaerobic exercise, again it was found that exercise intensity does not cause hypertrophic adaptations.
CONCLUSIONS
It is much easier to create an energy deficit from dietary restrictions, which should be the focus of an intervention aimed at weight loss.
However, exercise can help maintain lean mass, as well as facilitate the maintenance of weight loss in conjunction with a dietary intervention.
From the data provided by the meta-analysis in this article, we can conclude that effort intensity during exercise has little effect on fat loss and muscle mass benefits.
In practical terms, this means that one can choose the type and intensity of effort that best suits their needs and lifestyle, since as a general rule, high-intensity interval training requires less time but more effort than continuous moderate-intensity training to promote changes in body composition.
-Suprastratum: The authority on health, fitness and nutrition
Sources/bibliography/more reading:
- Steele J, Plotkin D, Van Every D, Rosa A, Zambrano H, Mendelovits B, Carrasquillo-Mercado M, Grgic J, Schoenfeld BJ. Slow and Steady, or Hard and Fast? A Systematic Review and Meta-Analysis of Studies Comparing Body Composition Changes between Interval Training and Moderate Intensity Continuous Training. sports (Basel). 2021 Nov 18;9(11):155. doi: 10.3390/sports9110155. PMID: 34822354.
- Maillard F, Rousset S, Pereira B, Boirie Y, Duclos M, Boisseau N. High-intensity interval training is more effective than moderate-intensity continuous training in reducing abdominal fat mass in postmenopausal women with type 2 diabetes: a randomized crossover study. Diabetes Metab. 2018 Dec;44(6):516-517. doi: 10.1016/j.diabet.2018.09.001. epub 2018 Sep 19. PMID: 30243615.
- Grgic J, Mcllvenna LC, Fyfe JJ, Sabol F, Bishop DJ, Schoenfeld BJ, Pedisic Z. Does Aerobic Training Promote the Same Skeletal Muscle Hypertrophy as Resistance Training? A Systematic Review and Meta-Analysis. sports med. 2019 Feb;49(2):233-254. doi: 10.1007/s40279-018-1008-z. PMID: 30341595.