Metabolic training commonly referred to as HIIT or high intensity interval training is huge in the fitness industry as of late due to many people’s grandiose claims about it. It can offer a ton of great benefits to your body but it comes at the cost of very intense work which is a major key many people lack in their training. Many peoples definition of HIIT is a little off and is actually a type of metabolic training. Metabolic training can be categorized as metabolic resistance training or cardio interval training. Metabolic resistance training is working through a circuit of resistance exercises (usually compound movements) with 30-60 sec of intense work with a short break in between working sets. Your average exerciser would probably consider that to be a HIIT workout however it is not, although similar. Cardio interval training is short burst of around 30 seconds of cardio based exercise followed by a minute plus rest period and this is technical definition of a HIIT workout. However the semantics doesn’t mean much because both are great for burning tons of calories in a quick and efficient workout. How does it compare to steady state cardio in improving body composition, EPOC, fat utilization, time and adherence.
The first experiment I will be referencing is a pubmed article in which they had a total of 43 obese young women on either a HIIT workout regimen, moderate intensity cardio training (MICT) workout regimen or the control which was no exercise. They were tracking body mass, body fat %, abdominal visceral fat and abdominal subcutaneous fat. Protocol for the intervention groups was for the first 4 weeks they were to exercise till they burned 200 kJ per session with 3 sessions per week. Then during the fifth through twelfth week they increased it to 300 kJ burned per session with 4 sessions per week. I presume they did it like this because their group are not regular exercisers and did not want to completely kill them with exercise from the start. What they found was that there was a decrease in body mass, body fat %, abdominal visceral fat as well as abdominal subcutaneous fat in both intervention groups however the two intervention didn’t vary much. This makes sense considering both groups exercised to burn the same amount of calories rather than a set period of time. However I would have thought HIIT would have had a slight edge due to EPOC and fat-utilization.
EPOC or excess postexercise oxygen consumption is as the name entails which in turn increases your calorie expenditure for up to 48 hours after exercise. In this pubmed article they compared the EPOC and fat-utilization in 4 different groups being MICT, vigorous intensity continuous training(VICT), sprint interval training(SIT) aka HIIT and rest. They had 8 active young men perform all 4 of the experiments. What they found was that total EPOC was similar between VICT and SIT with both being greater than MICT. Fat utilization increased for MICT, VICT and SIT compared to rest with the greatest increase after SIT. The data collected from this study would show even if you had two different workout strategies and exercised to the same amount of calories that the increase in EPOC and fat utilization would result in more calories burned after workout and therefore better body composition. A possible problem with this study is that it is a very small sample size. Another possible factor is that this study was done with young active men compared to the previous study which was done with young overweight women which may be a reason for results not being as you would except.
One last key point is time of workout as well as adherence to that workout program. We saw that there was similar body composition changes when burning exactly the same amount of calories however what needs to be considered is the time to achieve that. Metabolic training by definition is going to be high intensity and because you are going harder you are going to be burning more calories. Opposed to steady state cardio you are going to have to exercise at a lower intensity to be able to sustain that which is less calories per min. It has been shown that HIIT and MICT have similar health outcomes in a lab setting however you want to see how it applies to real life and this is what this pubmed article consist of. To test the effectiveness of unsupervised HIIT the study had 104 obese/overweight participants perform HIIT 3 times per week for a whole year. Essentially want is being tested is peoples drive and willingness to improve themselves when no one is around to tell them what to do and the results are not very surprising. Adherence to ≥2 sessions per week declined from 60.8% at baseline to 19.6% at the end of the 12 months. As you can see the drop off is pretty significant implying they don’t enjoy this exercise modality however the participants reported greater enjoyment of physical activity than conventional steady state cardio. And as you would expect participants that stuck to the workout program had greater reductions in weight and visceral fat than non adhering participants.
In conclusion I would say that steady state compared to HIIT is similar in everything except time and enjoyment. Steady state cardio is long, boring and repetitive in nature and doesn’t build a sense of enjoyment or they might not have the time and this is a recipe for disaster. It is hard for people to create time to do things they don’t enjoy. Fitness needs to be a lifelong activity and not something you do occasionally when you get a little to big for your liking. Therefore doing what you enjoy is key to long-term success. Adherence as we stated was an issue so you need to find a way to hold yourself accountable. A few ways I recommend to do that is telling your friends and family your goals, posting on your social media your goals, signing up and going to classes, or getting a personal trainer. These are all ways to get support from people plus these people know what you are trying to do so if and when you start to slip they will be on your butt if they really care about you.
Islam, H, et al. “Excess Postexercise Oxygen Consumption and Fat Utilization Following Submaximal Continuous and Supramaximal Interval Running.” Current Neurology and Neuroscience Reports., U.S. National Library of Medicine, Dec. 2018, www.ncbi.nlm.nih.gov/pubmed/30325710.
Kopniske, James. “Metabolic Resistance Training vs. Cardio Interval Training: Which Is Best for You?” STACK, 7 May 2018, www.stack.com/a/metabolic-resistance-training-vs-cardio-interval-training-which-is-best-for-you.
Roy, M, et al. “High-Intensity Interval Training in the Real World: Outcomes from a 12-Month Intervention in Overweight Adults.” Current Neurology and Neuroscience Reports., U.S. National Library of Medicine, Sept. 2018, www.ncbi.nlm.nih.gov/pubmed/29683919.