Wednesday, January 28, 2009

Intervals don't take long...and can prevent diabetes?

Interval training. Periods of harder exercise separated by periods of rest or easy movement. I've written about it a lot on this blog. Over the last 10 years or so it has been touted at the panacea to all training problems. If you google "tabata" you find over 2 million pages. Admittedly lots of these are about Japanese people called Mr Tabata, but most are about the exercise protocol.

In some corners of the internet there has been a bit of a backlash recently, with people like Mark Twight and Rob Shaul noting that while intervals can do a lot to benefit aerobic capacity, if you want to go long, sometimes you will need to train long too. ( I point to some of the discussion here). There was even a study recently that I saw some people jump on to say that intervals were nothing special or at least that they had been over hyped.

Effect of High Intensity Interval Exercise on Lipid Oxidation during post exercise recovery

The scientists compared intervals with a steady state session with respect to the effect on the amount of fat burned after the exercise was concluded. There was no difference.

Be that as it may this new research caught my eye.

Short bursts of intense exercise every few days could dramatically cut the risk of Type 2 diabetes and heart disease, according to an expert.
Rather than slaving away for hours in the gym, people should focus their attention on quick "sprints" with each workout lasting just a few minutes.
James Timmons, Heriot-Watt University professor of exercise biology has studied the effects of quick exercise.
He recommends 4 x 30 second sprints on an exercise bike three times a week.
He said people could reduce their risk of diabetes and heart disease substantially with short, intense workouts - with such "time-efficient" exercising appealing to busy workers.

The research that is referred to is here and the full paper is avaiable too.

Extremely short duration high intensity training substantially improves insulin action in young sedentary males

Classic, long duration aerobic exercise reduces cardiovascular and metabolic disease risk but this involves a substantial time commitment. Extremely low volume high-intensity interval training (HIT) has recently been shown to cause similar improvements to aerobic performance, but it has not been established whether HIT has the capacity to improve glycemic control.

Sixteen young men (age: 21+/-2 y; BMI: 23.7+/-3.1 kg * m-2; VO2peak: 48+/-9 ml * kg-1 * min-1) performed 2 weeks of supervised HIT comprising of a total of 15 min of exercise (6 sessions; 4-6 x 30-s cycle sprints per session). Aerobic performance (250-kJ self-paced cycling time trial), and glucose, insulin and NEFA responses to a 75-g oral glucose load (oral glucose tolerance test; OGTT) were determined before and after training.

Following 2 weeks of HIT, the area under the plasma glucose, insulin and NEFA concentration-time curves were all reduced (12%, 37%, 26% respectively, all P<0.001). p="0.058)." style="font-weight: bold;">Conclusions
The efficacy of a high intensity exercise protocol, involving only ~250 kcal work each week, to substantially improve insulin action in young sedentary subjects is remarkable. We feel this novel time-efficient training paradigm can be used as a strategy to reduce metabolic risk factors in young and middle aged sedentary populations who otherwise would not adhere to a classic high volume, time consuming exercise regimes.

I think the conclusion there is a really important thing. Intervals have a profound effect metabolically, they can have a major effect on health but they do not take long: 4 x 30 secs with some rests between sees the session over in 7 minutes a week. It is hard to claim that you do not have the time to do this. Some people are put off exercise because of the perceived time commitment but they need to know that they can exercise in such a way that they can benefit their health without needing much time.

Maybe other training protocols can have a similar impact....but none are as time efficient. I'd also argue that intervals are more natural and playful, but that is a different discussion.

The researcher here explained how intense intervals can help:

"Think about diabetes as being glucose circulating in the blood rather than stored in the muscles where it should be.

"If we take out the glycogen from the muscles through exercise, then the muscles draw in that excess glucose from the blood."

"If you go for a jog or a run you oxidise glycogen but you are not depleting the glycogen in your muscles.

"The only way to get to this glycogen is through very intense contractions of the muscles.

"If we can get people in their 20s, 30s and 40s doing these exercises twice a week then it could have a very dramatic effect on the future prevalence of diabetes."

Maybe the tide is turning and rational exercise (and diet) will oen day be mainstream? The video is worth watching.

As usual the NHS is sceptical!

More here



Asclepius said...

One of the guys who wrote this paper was on a website giving it the old 'eat less do more' line:

The thread discussed Steve Redgrave's diet and his subsequent diabetes, and mention was made of Michael Phelps. The following article might make us ALL think more about conditioned eating and/or non-paleo diets:

Chris said...

Cheers Asclepius - interesting.

Thorpe has not kept in shape has he!

Asclepius said...

He hasn't! I am hoping there are no underlying issues other than the fact that he is a carboholic.

I guess that as long as he is happy then we should be happy for him.

Stargazey said...

Chris, this idea--that short bursts of intense exercise would improve insulin responsiveness--makes a lot of sense. I hope the investigators go ahead and see if this holds true for older subjects who have had more time to become insulin resistant or pre-diabetic.

Regarding the Jimmy-Moore-in-denial-about-his-menus situation, I think I shall go with your advice and just stay quiet. He seems to have serious issues about admitting the effect of frankenfoods and sweet tastes on his low-carb program. He only lasted a week on Dr. Westman's diet. He only lasts a few days or a few weeks on his sweet free pledges. Some day, perhaps, he will understand that aging is what it is. He may have lost lots of weight on a particular way of eating, but he is not the same person he was five years ago. And all the rationalization in the world does not fool Mother Nature.

Anonymous said...

In regard to the intervals/fat loss study, it looks as if (from the abstract, at least) that these are what I would consider very long bursts. That, and I cannot tell how many bursts were performed (surely not an hour's worth). I'd like to see the same study done using a protocol of *very* high intensity bursts (i.e., max power output, <20 sec's duration). Empirically speaking, I know this kind of short-burst, intermittent intensity is highly effective at cutting fat.

Asclepius said...

From the UKClimbing website thread referred to above:

Good to see some interest in this paper! I was leading this study at Heriot-Watt University (Professor Timmons funded it).

-we believe the key mechanism for the effects of our protocol to be the rapid decrease in muscle glycogen (~33% decrease in one session / 4 x 30 sec sprints). With running this would take far longer (faster with increasing intensities), whereas jogging hardly reduces muscle glycogen at all. Liver glycogen is not important in this (liver glycogen is depleted overnight and repleted during the day).

-Inactivity is the main cause of Type II diabetes, eating large amounts of carbohydrates is not a problem whatsoever. If you are sufficiently active your diet does not really make much difference, whether it is high fat, high protein or high carbohydrate. Research suggests a high carbohydrate diet to be the healthiest option. This is despite the fact that a wide range of other diets have been shown to reduce body mass. You should bear in mind that loosing weight depends on the balance between calorie-intake and calorie expenditure, and NOT on whether these calories come from fat or carbohydrates. However, body weight is not the only important health parameter: a high fat diet increases health risks through other mechanisms. Moreover, endurance performance benefits from a high carbohydrate diet.

-On the applicability of our protocol: this stuff works amazingly well, but is NOT an easy option, 4 x 30 second Wingate tests are very tiring. However, it not only reduces risk of insulin resistance / diabetes, it also improves aerobic performance / endurance. This won’t improve your climbing performance, but is very useful for long days in the mountains / walk-ins / etc. You can get similar adaptations with endurance training, but this takes far more time.

Chris said...


thanks for that. All the tired old orthodoxy that is actually a pile of crap!

A high fat diet is great and endurance performance - especially - is fuelled by fat not carbs and is perfectly OK on a ketogenic diet - there is a guy called Phinney who has done a lot of research on low carb diets for endurance - e.g. see this paper

or this one

in many ways this is not a new idea although this guy presents it as if it is something novel. For example this post from about a year ago looked at research - the whoel PhD is available - about intervals of 8 seconds on and 12 off.

Cheers again


Stephan Guyenet said...


That HIT study you posted is very impressive! 37% reduction in the insulin AUC. If what matters is intense muscle contraction, then you'd expect weight training to do the same. Do you know if that's the case?

Chris said...


the full paper is linked above and does give more information that the abstract. 4-6 sprints with 4 minute recoveries between each.

With respect to shorter bursts, this post looked at 8 second sprints which were really good fat burners.

Chris said...


I'm not sure but it would make sense and there are studies out there - e.g. this one - that indicate that weight training improves insulin sensitivity.

There are several others out there.

Asclepius said...

Chris - excellent work. I am not sure how you manage to find all this stuff but it is great that you pull it all together in one place!

Looks like I have got some reading to do! ;)

Chris said...

I have a very sad life..... ;-)

Anonymous said...

-Inactivity is the main cause of Type II diabetes, eating large amounts of carbohydrates is not a problem whatsoever. If you are sufficiently active your diet does not really make much difference, whether it is high fat, high protein or high carbohydrate. Research suggests a high carbohydrate diet to be the healthiest option.

Ouch! :(

Tell that to my skinny active running walking cousin who has many signs of insulin resistance.

Tell that to his skinny active running walking swimming marathoning triathloning daughter who at half his age has even more signs of insulin resistance.

Tell that to me after fifty years of reactive hypoglycemia and appalling lipids which have mysteriously normalised on a diet of around 60 - 100g carbs which has also greatly improved my energy levels, although I was never inactive either. And the only time I put on weight and became lazy was when I was put on a Heart Healthy Low Fat High Carb diet. Made my lipids and BP significantly worse too.

I find significant differences in the effects of exercise depending how close to the meal they are, long term stuff like walking serves to keep the blood glucose in range and the *familial* insulin resistance down, short bursts of exercise immediately after eating while my funky pancreas has actually decided to generate some insulin can actually send me temporarily hypo. The downside of that is the effect on cortisol and epinephrine etc. which may outweigh the direct effect on IR and glucose disposition.

Certainly looks like something well worth experimenting with but probably not doable for everyone (there are somewhere over 50 genes now associated with Type 2 and others associated with obesity and MODY diabetes so it is certainly NOT a unitary disease and while environment certainly alters the gene expression it is in no way The Cause)

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