Hourly 4-second sprints prevent impairment of postprandial fat metabolism | Hacker News Reader

Hourly 4-second sprints prevent impairment of postprandial fat metabolism

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168 pointswallflower131 comments

'Hourly 4-second sprints' is actually 5 times an hour 4 secs (bicycle) sprints. So it is more precisely about every 12 minutes. I do not understand why it says 'hourly'? Because it sounds less often?

It must be one set of 5 reps per hour, not one sprint every 12 minutes.

That's how exercise usually works, and the study is concerned with the "least amount of exercise that can acutely improve fat metabolism and other aspects of health". Activity spaced out every 12 minutes would be disruptive and defeat that purpose.

Article states 4s activity followed by 45s seated rest, repeated 5 times. So you're actually occupied with the workout task for 4m+05s every hour, even though only 20s of that is sprinting.

And it's not an activity you'll do at or near your desk, so you're going to have to travel somewhere to do it.

It depends on your desk.

True. And the location of said desk.

Thank you, so that explains the 45-s rest mentioned.

I assume then each 4-s workout is followed by a 45-s rest. So 49-s * 5 = 245-s (4 min) spend each hour on the excercises.

you have an off by one fencepost error ;)

You only need to rest four times!

Fencepost error– great visual, thanks

> This study determined if the interruption of prolonged sitting (i.e.; 8-h of inactivity) with hourly cycling sprints of only 4-s duration each (i.e.; 4-s x 5 per h x 8-h = 160-s per day; SPRINTS) improves PPL. The 4-s sprints employed an inertial load ergometer and were followed by 45-s of seated rest.

So you would need to take a 5 x (4-s sprint + 45-s rest) = 245 seconds exercise break from work every hour and in return you could get the following results?

> No differences (p>0.05) between interventions were found for plasma insulin or glucose AUC. However, SPRINTS displayed a 31% (408±119 vs. 593±88 mg/dL/6h; p=0.009) decrease in plasma triglyceride incremental AUC and a 43% increase in whole body fat oxidation (P=0.001) when compared to SIT.

Does "whole body fat oxidation" mean that the an average male calorie burn of 2500 per day would be multiplied with 1,43 to 3575 calories per day?

Fairly easy to incorporate this into a pomodoro cadence. Every other break do some high intensity bursts.

Well, presumably you can work while resting. Honestly, I haven't found that to be too hard (I take a mid-day bike ride up the hill here in SF).

> Does "whole body fat oxidation" mean that the an average male calorie burn of 2500 per day would be multiplied with 1,43 to 3575 calories per day?

It seems extremely unlikely to me. I hesitate to bring up the 2nd law of thermodynamics because I know if frustrates a lot of people in these discussions. However, bear with me.

"Calories" in this context refers to kilocalories. Burning 1 kilocalorie produces enough energy to raise 1 kg of water 1 degree C. So burning an extra 1000 kilocalories per day means producing enough heat to raise the body temperature of a 100 kg person 10 degrees over the course of a day. Although our bodies are really good at cooling, that's not an insigificant amount of heat. It's of a magnitude that is relatively easily measured.

If such a phenomenon were to exist, it seems inconceivable to me that the researchers would not try to measure it. I mean it is literally the holy grail of dieting. I think it is considerably more likely that the effect they are measuring is very interesting, but does not extrapolate out to this logical conclusion.

Your analysis seems to be in the right direction but I think that the body uses this energy in many more ways than just heat. Moving muscles, pumping blood, keeping ionic gradients in the kidneys, and in cells, producing waste products, do seem to take energy. Also, consider the water we lose due to evaporation just by breathing, we are constantly creating a significant amount of heat and dissipating it into the environment. This extra 1000Kcal would be roughly a 50 watt increase in average metabolic rate during a whole day.

It does seem a bit high but anecdotally, my body temperature is 1C higher on days I do some tennis early in the morning. And more importantly my oftenly cold hands go away, so radiating more of it away.

> This extra 1000Kcal would be roughly a 50 watt increase in average metabolic rate during a whole day.

This calculation makes the theory implausible. A resting human burns about 100 watts[0], this would imply 50% more energy output than that, over the whole day.

I too find that I'm warmer after a workout, and sweat lightly for up to a few hours after my heart rate returns to normal, which itself takes almost an hour. So burning more energy than the workout itself? Absolutely.

1000 calories extra seems high for ~4 minutes of cycle sprinting per hour. The HIIT pacing of it is probably ~just as good as spending the whole 4 minutes cycling steadily though.

All energy leaves the body as either work or heat, so of the processes you mentioned, moving things or yourself with your muscles is the only one that wouldn't raise temperature.

I'm not denying the 2nd law, but metabolism is more complicated than just heat or mechanical work. One example, the process by which the body transforms ammonia into urea, requires energy. Not 100% sure of the details but some of this energy might be captured chemically, not sure if urea has a higher (free energy? I don't remember the exact term). Furthermore with this example, since urine is hyperosmotic, the body has to do a process against normal ion/water diffusion, in order to excrete minerals and not excessive water. This osmotic pressure, contains some potential energy.

The thing is that because of the 2nd law of thermodynamics, that energy does not go away when we use it. Moving muscles, pumping blood, etc uses energy and transforms it to heat. It's a bit weird that energy doesn't go away when we "use" it, but that's how the universe works :-) What can happen is that energy is locked up in chemical structures (or, I guess as physical potential energy). So if you evaporate water, the energy goes into the water and stays there until the vapour condenses. Things like that. But it's pretty easy to isolate a person and measure the amount of heat they produce (to a gross level like we are talking about here).

But, yes. Exercise will drive your metabolism and cause you to be warmer.

It's easier to measure the volume of exhaled air and extrapolate calories from that, via CO2 expelled.

Different fuels create different amounts of CO2 per joule though. This is not just a truism in combating climate change but also a key tool when observing metabolism. Whenever someone gives numbers for how much of some exercise energy consumption is from fats and how much is from carbs it is determined by measuring CO2 output and comparing that to measured energy output.

Oh huh, I hadn't realized that, thank you!

Yeah, completely agree, no one is denying the 2nd law :) Let's just say biochemistry is quite complicated with myriad metabolic pathways. I find it plausible that the body does not necessarily use all calories ingested all the time. Some probably remain in the digestive tract.

You mean the 1st Law.

There are other places than heat (e.g. synthesizing muscle and other types of tissue) for the excess energy to go.

> I mean it is literally the holy grail of dieting.

Slightly related but I have recently visited the US and I have been shocked how supercharged high sugar (ie addictive) high calorie foods are everywhere, like desserts above 1000kcal alone. It takes much more effort than in the other countries to manage caloric intake here, even eating random junk food where I live it’s hard to go above 3000 per day.

There's definitely an obsession with a good value in America, so everything you find in a restaurant is ultra high in calories. Even seemingly innocuous foods are probably sauteed in pounds of butter and made as criminally unhealthy as possible. It's like they're engineered to make you fat.

That being said, if you're looking to stay inside your clothes while visiting America, avoid eating at restaurants entirely.

While kind of you to say, we Americans don't put butter on everything because we're looking for a good value.

I know, I was like wait where are these restaurants? I think most places use cheapo oil and margarine.

What I meant was, fat adds to the flavor, and blows up the calories, in turn making you fuller and thus you think you got a good value for your dollar.

how so much more effort? unless you’re in the worst parts of town there are plenty of food choices. choose the good ones.

Interestingly enough, a similar phenomenon does exist when using a compound called dinitrophenol. Naturally, like with every useful drug, it's been demonized and banned. What it basically does is make energy use inefficient, so a specific action (like clenching your fist) consumes more energy than normal.

Not all of those 2500 calories come from fat. Some will come from protein, carbs, and alcohol. Even if your body doesn't burn less of the others to compensate you would not get 1.43 times your normal calorie burn.

> Does "whole body fat oxidation" mean that the an average male calorie burn of 2500 per day would be multiplied with 1,43 to 3575 calories per day?

No, it means they burned (oxidized) more fat. This would mostly be a higher % with same calories. Doing those tiny intervals of total 2m40s shouldn't raise significantly the total calorie consumption.

I think we get energy directly out of carbohydrates and proteins, too. If so, that factor will be (¿much?) lower.

No it means the amount of calories coming from body fat is increased by 43%, which may amount to nothing over the course of the day if it also simultaneously increases appetite. Almost all forms of weight loss suffer from this problem - the amount of fat lost is generally proportional to the long-term appetite increase, so that 95% of people regain the weight.

2500 calories is way over the average male rmr

Ah, the sprint is being rediscovered once again for it's ability to squeeze maximum effect into minimum working time.

If you get a chance, try to find a copy of "A System of Multi-year Training in Weightlifting" by A.S. Medvedyev (a translation of the 1980s Soviet Olympic Weightlifting program for coaches).

It's the culmination of decades of studies across the entire Soviet athletics program about what works and what doesn't.

The summer programming shifts almost exclusively to sprinting, and only a few hundred meters per day, because that's what they found is enough work for anyone who isn't a specialized running athlete.

I follow it as soon as I can ever summer and it's immediately obvious that my metabolism increases.

IMO the secret about sprinting vs distance running is that your body can't optimize for efficiency. You can marginally increase ATP capacity, but the only thing getting better at maximum effort sprints does is make you able to produce more power while doing maximum effort sprints. It stays hard, without needing to increase volume much over time.

Can you plz share how do you incorporate sprints in your training plan?

"Four men and four women participated in two trials"

I'm not a medical researcher; is this a normal size for a study?

I thought the exact same. I honestly think this post should be deleted on that fact.

It's enough for such a large effect, but obviously it doesn't tell us anything about the long-term impact of trying it as a lifestyle.

There are two problems: "No differences (p>0.05) between interventions were found for plasma insulin or glucose AUC." That can very, very much be explained by lack of power. But the main problem is that a group of 8 people has a very low probability of generalizing across the population. And of course, very few people sit 8 hours without moving.

That said, it's more than promising enough for further research.

Say you are trying to distinguish between a placebo and a cyanide pill; test subjects are young rats (base rate of death extremely low). How large of a sample size do you need? I think one control, one test subject is enough to be certain, because the base rate of death is insanely low, when measured on a per-minute basis.

Sample sizes can be small and still very significant when the effect is large.

I would want about four of each rat still. The control could die of something else...

I'm quite confident the only reason to use four rats in a study of cyanide is that you really want to kill two rats.

Yeah, because you already have a very well-established prior on the effects of cyanide.

> when the effect is large

You mean when the effect is guaranteed. Cyanide is reasonably guaranteed to have the expected effect every time which is why you don't even need the control.

With only 4 test subjects you can't really draw a strong conclusion.

Maybe it's a relatively quick and cheap way to decide if it's worth doing larger and longer studies.

Voice of reason

Medical research is expensive to conduct, so it's not uncommon to see N<20. Additionally, more data is not necessarily better data since humans lie and it's unethical to force their compliance, so there's more of a risk for bad data with large trials. And throwing out bad data is selection bias.

And here I thought this was about software development.

According to the [site guidelines](https://news.ycombinator.com/newsguidelines.html):

> Hacker News Guidelines

> What to Submit

> On-Topic: Anything that good hackers would find interesting. That includes more than hacking and startups. If you had to reduce it to a sentence, the answer might be: anything that gratifies one's intellectual curiosity.

> Off-Topic: Most stories about politics, or crime, or sports, unless they're evidence of some interesting new phenomenon. Videos of pratfalls or disasters, or cute animal pictures. If they'd cover it on TV news, it's probably off-topic.

I'd say this falls under "anything that gratifies one's intellectual curiosity."

I think they were trying to make a joke about sprints and agile software development.

I'm 7 pounds into the "Covid 15" despite daily exercise. I may give this a try and see if I see results

Right before the pandemic, I entered a body composition challenge that just ended. I lost ten lbs of fat and gained one lb of muscle. Another guy lost 6 lbs of fat and gained 4 lbs of muscle. You can't trust your scale. Go by the scale in addition to how you look, how your clothes fit, and your body measurements.

For better data, get a Dexa body scan.

Yeah go irradiate yourself just to find out how fat you are, what could go wrong?

True, but if my activity levels have dropped, I can be pretty sure my weight gain is almost entirely fat. Now that I've gotten back to being more active the past two weeks, I hope to see some results in the mirror before I worry too much about the number on the scale.

In my case, the scale number will regularly fluctuate a few pounds just based on time of day or short-term variations in activity and diet.

There's only a handful of them[Dexa] in the USA, if I want to find something local (Kansas City) what should I be looking for?

I'm from Utah, so I really have no clue, but a quick search revealed this: https://www.dexafit.com/locations/kansas/kansas-city

NICE, thanks, something I'll look into

FWIW it will be easier to lower your caloric intake to align with the lower activity that is a result of lockdown lifestyle than it will be to boost activity to try to match pre-lockdown lifestyle.

Weight control is practically entirely diet. Exercise achieves other health and lifestyle goals.

Furthermore optimizing your diet during lockdown will pay dividends once you go back to a standard level of activity post-lockdown.

Not to say you shouldn't continue daily exercise, point is if you are trying to control your weight you are focusing on the wrong "lever."

The thing is I want to eat. Not the op.

I had this problem too, I was able to solve it by replacing most of the carbs I ate with fat and protein. This led to stable insulin levels which led to ghrelin being only released during normal meal times which is nowadays only one for me around 11 am.

Not trying to say that Omad is for everyone but the reduction of carbs was the perfect key for handling my hunger attacks.

I know, everything you say is absolutely spot on :( it's just so much easier to motivate myself to workout than it is to diet. I was rowing (erging) twice a day burning an extra 500-1000 calories (pretty easy to do on a rower in about an hour of rowing per day).

Now that's Agile

We've found that continuous flow works better than 4-second sprints.

This study used cycling sprints. I wonder if a similar effect would be observed with say, a set of pushups or squats every hour

Or burpees.

Sure why not? Mix it up.

They probably picked cycling because it's easier to measure and there's less variation. And there's much more literature on it (e.g. Tabata/HIIT protocols). I feel squats properly done would be even better as more muscles are involved. With the added benefit of not needing equipment.

Probably. But I think the body gets Abit tricked when the legs come into play in a locomotive fashion.

Particular sprinting. It's primal.

Leg muscles are a lot larger. You can easily stay warm while cycling or walking at a brisk pace in the winter. Less so when standing still and doing pushups or situps.

Who has time to do 4s sprints???

yeah because after my 4s sprint it will take me 20s to walk back to my desk.

Past the rest of the open office floor-plan as sales stares.

It was strange at first, when everyone got their Apple Watch and started standing up, seemingly at random, in meetings. “Gotta meet my stand goal!”

Gonna be really weird when they go tear-assing down the hallway

Oop, someone's got the zoomies!

Ok 4s/hour. 8 hours/day of sitting. So 32s day of total exercise!?!

Still probably will not do it.

That is also how I initially read it, but the paper states that there were 5 sprints per hours for a total of 160 seconds a day.

From the paper:

> i.e.; 4-s x 5 per h x 8-h = 160-s per day

Still probably would not do it. But why?

I wonder what other exercise modality this could be replaced with. Do 3 squats?

1 flight of stairs.

a good comparison!

Sprinting up a flight of stairs, then walking back down, and repeating it five times, once an hour.

That I have a good gauge of. Yeah, that would feel good. Pity I live in a first-floor flat...

I mean this sounds way healthier to me than endless cardio. That is much more taxing for the body. This short sprints could certainly spike metabolism without the running out of limiting factors that happens with endurance exercise. Net effect, your body stays in a physiologically high activity state without producing excess stress hormones. Sign me up

It's not offering all the other benefits of exercise (ie. building muscle and cardiovascular health). You're not going to not get fat doing this, and I doubt it'll keep you from being out of breath while climbing the stairs.

Cardio builds very little muscle. Take it from the mouth of a quite competitive high school runner. Used to run about 30km per week (not high by many standards, exceedingly high by my current standards). Diet and lifestyle are more important for fitness. Endurance exercise is pretty bad for the heart, just look at the marathon runners. Ouch. The thing is cardio becomes addictive as most people have low intrinsic energy (due to diet, lack of sun, etc...) so when they release stress hormones through cardio they now feel a bit better. Not very sustainable in the long run. Look at our history as a species and nowhere do I see much cardio until the 20th century. Activity for sure, sign me up. Cardio as understood nowadays with endless running and crossfit? Only thing I might actually run away from

Don't we need to warm up before doing any max intensity exercise to prevent injury.

I've read conflicting information about warming up over the years but it at least appears to me that the consensus is slowly moving away from several common exercises such as stretching, which apparently even seems to have negative effects.

Stretching will decrease strength immediately after. Dynamic warm-ups where you work up to the range of motion of play is what you want. Greasing the groove is another method to Google. Stretching is useful to increase range of movement if you don't have enough for a given sport. Injury prevention is more focused on eliminating muscle imbalances.

It is mostly deep stretching before exercise that seems to be the biggest target. Light quick stretching should still be fine to prevent injury. Deep stretching is only good for maintaining or increasing flexibility especially when bulking up, but should been done as its own exercise with rest afterwards.

Static stretching should be avoided at the beginning of a workout.

I had assumed this was about sprinting in the sense of running as fast as possible, which would be absolutely insane to do without a warmup. I take around 20 minutes to warm up for sprinting, doing very specific exercises to prepare.

On a stationary bike though, because the range of motion is much more controlled, I can see it being a little less of an issue.

Since you're doing this every 12 minutes, you'd stay relatively warm all day. American football players don't need to warm up every time they come off the sidelines

But they do... lots of teams have stationary bikes on the sidelines. No athlete would sit motionless for 12 minutes in the middle of a competition, not too mention that players would go through a much longer warm up before the game.

But I agree that going full force very briefly on a stationary bike with no warmup is probably fine for most people.

Fair, but a lot of them do sit on the bench and do some moderate walking at most.

I'd expect people doing these regular sprints to be more aware of their body and move around more in anticipation of the next set.

I am curious if the same effect could be achieved if I just jump on jumping rope for 20 sec every our? I can even jump for a minute!

The control group was asked to sit for 8 hours straight, whereas the experimental group sprinted five times. It would be more interesting if they compared it to standing up.

> whereas the experimental group sprinted five times

Per hour.

If tried an intense exercise, regardless of how long, without warming up I would hurt myself really fast.

Searching for exercises having an efect and taking as less time as possible looks like panacea.

OK, so what's a "4-s sprint"?

I presume that this employs a stationary bicycle. But against what resistance? Also, four seconds hardly seems enough to even reach maximum exertion.

Jumping cold out of your couch/chair and sprinting 5 seconds every hour, multiple times a day, sounds to me like an optimized 'quickly destroy most of your body joints' routine.

You can do low impact. Burpees aren't too rough.

Burpees are actually super high impact. Done warm, let alone cold, they can cause patellar tendonopathy, back strains and hamstring strains.

This paper says cycling - I’d be inclined to agree. Obviously that’s a barrier to entry, because you’d want an indoor stationary bike. On low resistance settings the risk of injury would be very low coming in cold.

It happened on a stationary bicycle trainer -> Low load on joints, as most of the weight rests on the saddle and handlebars.

The University of Bath minimal HIIT protocol also used stationary bikes (3 20" intervals 3x/week).

Getting 20 inches on a stationary bike can be hard enough.

(couldn't resist. I actually didn't know " ("double prime") could mean seconds.)

Both temporal and angular!

Keep in mind that research in sports science is biased towards equipment like bikes because they make the study so much easier - safer to use, ensure consistent form, easier to get approval for the study and there's no need to coach the participants all that much.

I'm more worried about repetitive stress injury from being typing and using the mouse.

To me - it sounds like a great way to throw up or at least get stomach sickness.

I can't imagine going full send with no warm up and not suffering some sort of issue after stopping.

Your warm-up accrues though. You're doing a little bit of exercise every 12 minutes for 8 hours.

You're not going to get sick.

Nitpick: the 4-second sprints weren't evenly distributed into each hour. They were done in sets of 5 with 45-second rest periods between sets.

I don't know how to put this kindly, but eh... if you can't exercise for 20 seconds, you might be a bit out of shape.

Depends on your health. I'm 50 and healthy, I can easily "full send" a 30 or 60 second sprint. I have friends my age and younger who probably can't, for different reasons.

Warm up for a 20 second sprint on a stationary bike? Getting on the bike would be enough warm up...

You won't be cold though, because you're doing 4sec of exercise 5 times an hour.

How about jumping jacks?

Probably not, jumping jacks don't take much effort. Think about for how long people can sprint at their maximum speed: 3 minutes would be world class. But doing 3 minutes of jumping jacks is pretty easy.

TL;DR:

An hourly ~5min cycling exercise on a stationary bicycle trainer results in a 31% decrease of area under the curve (AUC)* of postprandial triglyceride levels in blood plasma and a 43% increase in whole body fat oxidation.

The cycling exercise consisted of five 4-sec all out sprints followed by 45-sec rests.

The exercise was performed once per hour during 8 hours of sitting and compared to 8 hours of pure sitting.

[*]: https://stats.stackexchange.com/questions/132777/what-does-a...

> Four men and four women participated

Is all exercise science this weak?

sadly, almost all of it is based on samples around this small.

p(0.05) and p(0.0001) with 8 people sample? It is hard to understand those probabilities.

I'm confused. "Hourly 4s sprints" sounds like one 4 second sprint every hour but the second paragraph of the summary says

> Purpose

That's 5 per hour not 1 or once every 12 minutes

Me too. Title is confusing

Every hour, they do a workout that consists of 5 repetitions of 4s sprints.

Ah, this is probably what they meant. Very poorly explained by them.

Jira is confusing too.

Especially if your sprints are four seconds long

> "Prevent Impairment"

So, is that a double negative and this would mean it improves fat metabolism?

This was done on purpose Every hour but you can get similar results with one longer Training session. Heck I only train 3-5 days per week and problem burning fat with enough intensity or volume.

>>"Four men and four women participated in two trials"

My uncle smoked 3 packs a day and lived to 90.

other than that, maybe just getting up and putting strains even for seconds might do the job /trick our body.

I think this is mostly a curiosity.

Why do people think this is relevant for HN? Is people seriously trying to "hack" their metabolism? What for? Being able to spend, say, 16 hours sitting in front of a computer typing code away?

As I get older, I more and more realise the negative health impacts of a mostly sedantry job - anything to offset that is surely in the interests of most HN readers

Being sedentary seems to be really bad for you and programmers are the forefront of this as we spend lots of time motionless.

There seems to be correlations with major diseases as well as muscular skeleton pain. It’s not even 16 hours. Even 8 hours seems to be bad,(especially if it’s not spread out), since we live in a pretty sedentary world now.

I’ve been following these threads on hacker news as I want to prevent as much pain and diseases as I can.

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