A curious question that came up recently on twitter. I always thought that low intensity was the fat burning area – that’s what my coach has always said to me. This is how my metabolic tests always come back:
Heart rate is measured along the bottom. So, I start the test walking, and it gets harder and harder, higher hills, faster pace, till I can go no longer. I am hooked up to a heart rate monitor and a machine measuring oxygen output. So, as you can see, it tells me that I am 100% fat burning at the easiest intensity.
I asked David Sutton – Strength and conditioning coach, (@PerformTrain on twitter) why he was telling me the opposite. He said this was showing me calories from fat (burning the fat by means of burning calories while exercising).. Eh? That is what a generic definition will show you:
Fitness Zone (Fat Burning) --- 60 - 70% of maximum heart rate: This zone provides the same benefits as the healthy heart zone, but is more intense and burns more total calories. The percent of fat calories is still 85%. http://www.thewalkingsite.com/thr.html
But what DOES THAT MEAN? His explanation was that burning calories from fat is higher in low intensity work, however high intensity and resistance training = more fat burning overall and higher MBR. (Base metabolism rate). This sounded like the opposite of what I have always known. As always, he then sent me some research to back it up.
The Research Bit:
Aerobic and progressive resistance training was tested on two groups, one group did cardio, one progressive resistance training. Weight, body mass index, body fat, waist circumference, waist:hip ratio, blood pressure, and peak oxygen consumption were all measured.
Results: ‘significant between-group differences occurred in change in waist circumference in favour of progressive resistance exercise and in change in peak oxygen consumption in favour of aerobic exercise’ http://www.ncbi.nlm.nih.gov/pubmed/20795922
So, were both theories right then? It seems so. There’s more.
Research: 'Effect of exercise training intensity on abdominal visceral fat and body composition'
This one was examining the effects of exercise training intensity on abdominal visceral fat and body composition in obese women with the metabolic syndrome. The groups were given different levels of exercise: none, minimal, low, lactate threshold and high.
RESULTS: ‘High intensity exercise significantly reduced total abdominal fat, abdominal fat and visceral fat. There were no significant changes observed in any of these parameters within the Control (none) or the low intensity conditions.’ http://www.ncbi.nlm.nih.gov/pubmed/18845966
They conclude that high intensity work is best for reducing visceral and abdominal fat. This Theory would also be supported by the other study.
Search this term and you will see many more that support the theory:
http://media.cybexintl.com/cybexinstitute/research/research_TheAdvantagesOfHighIntensityTraining.pdf
My Conclusions / opinions:
· High intensity exercise can it seems, be more effective in lowering body fat % -the opposite of what I actually thought!
· BUT... without a cardio base, you will tire faster, lose speed and overall end up slower
· Both are important, but if burning fat is the aim, a good cardio base with enable you to work at a higher intensity for longer... will it not?
· Both high and low intensity work have their own advantages and one should not be omitted in favour of the other
So if I read that right, you should just do one or the other. Somehow incorporate both into your exercise routine?
ReplyDeleteHi Jay,
ReplyDeleteThis article may explain it better.
http://www.dummies.com/how-to/content/busting-the-great-myths-of-fat-burning.html
'Myth: Exercise done at a low intensity, such as walking, is better at fat burning than other high-intensity activities, like running or cardio activities where you push yourself very hard.
The Truth: In a strict scientific sense, these claims are true because working at a lower intensity requires less quick energy and a higher percentage of fat is burned. But you'll also burn fewer calories than you would if, for the same amount of time, you work out at a harder intensity (running versus walking). If you're trying to lose weight, even though a higher percentage of fat is being used, a lower total amount of fat is lost.'
Low intensity work burns calories from fat, yes. You could go for longer because you are working at an intensity that doesnt eat into your carb stores (of which there is a limit).
However, to be more effective at burning abdominal and visceral fat higher intensity is better.
Now, you wouldnt last long at a high intensity if you were not fit in the first place, yes? so, lower intensity exercise builds up your fitness, so that you can sustain the higher intensity work for longer.
So, if we all raced around at a speed of knotts and did no slow work, you wouldnt last for long and would be knackered all the time!
thats how I understand it.
Ultimately though, if you only have 1/2 hour, a quick run will burn more calories than a slow run (if its fat burning and weight loss that you had in mind)
does that make sense?
By the way, I was not for a second suggesting you are a 'dummy' Jay, its just an unfortunate name for the web site where i found the easiest to understand explanation!!
ReplyDeleteHope you weren't offended!!