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Dave Smith unleashes the fact burning zone

A couple of weeks ago I’d have worn out the batteries in my Face Palmer if I had one. Another online article that on face value appeared to make perfect sense, referencing a research paper no less, related to ‘fat-burning’ rides. The reality however was that the interpretation was erroneous, condemning numerous cyclists to riding along at 14 mph to ‘burn fat’.

The only thing that grates with me more than the use or even consideration of the use of the term ‘anaerobic threshold’, is the utter confusion that surrounds the term ‘fat-burning zone’. It’s understandable given the terms adoption by the fitness industry, but let me tell you a little secret. The fitness industry embraces the fat burning zones on their cardio equipment to help the unfit think they’ve done a valuable workout. I know this as a director of one of the world’s largest fitness equipment manufacturers said it to me. He conceded that ‘fat burning zones’ had little real value, but stated that “most people who go to a gym don’t want a strenuous workout”.

But back to bikes

The first issue with fat burning zone, is that it exists. There is certainly a level of intensity at which fat contributes a greater proportion of energy to fuel exercise. The level of intensity varies from one individual to another and also within one individual from day to day, based on training status and nutritional inputs.

For example, if you wake up and exercise in a fasted state, you’ll burn more fat and at higher intensities than after a carbohydrate breakfast.

So what’s my problem?

Quite simply, this fat burning zone is something you should pretty much ignore if you wish to lose body fat. That’s a prime example of those sneaky counterintuitive things. There are several reasons to eschew the slow plodding rides that will have you favouring fat over carbs as fuel.

The first is that you’ll burn very little body fat in the first place. One gram of fat is worth 9 calories. Since ‘fat-burning zone’ exercise burns roughly 140 to 180 calories in 30 minutes, with an estimate of 50 to 60 percent of those calories coming from fat it translates 8 to 12g of fat in 30 minutes - or two times that amount in an hour.

Good luck losing that stone. 

The second reason to avoid long slow training sessions is that they increase appetite, whilst high intensity intervals suppress appetite. So you may have done 3 hours and burned 60 grams of fat (whoop) but you’re more likely to reach for the tub of ice cream afterwards.

An interval session will have a greater calorie cost when recovery metabolism is included, and also suppresses hunger. Whilst losing body fat is not a simple case of ‘calories in calories out’, calories do play some part in waist management.

You don’t believe me, do you?

Boffins at Laval University in Quebec* had two groups participate in different exercise sessions. Seventeen subjects trained on an indoor bike four to five times per week for 20 weeks, with workouts lasting from 30 to 45 minutes and exercise intensity ranged from 60-85 per cent of maximal heart rate.



A second group of 10 subjects completed 30-minute workouts at an intensity comparable to that attained by the first group. However, the second group also conducted 19 short and 16 long interval sessions during their 15-week programme. The short-interval sessions consisted of 10 to 15 intervals lasting for 15-30 seconds, while the long-interval efforts were composed of four to five intervals with durations of 60-90 seconds.Total energy expenditure during training was twice as great in the first group as in the second group – they burned more calories. However, each group achieved about a 30% increase in maximal aerobic capacity. Most surprisingly however, the interval-trained athletes (who performed less total work remember) had a 9x greater loss of body fat than the first group.

This research was done more than 20 years ago, yet the misconception still exists that low intensity exercise in your ‘fat burning zone’ is best for losing body fat, hence my palming of the face last week.

Still not convinced? Try to recall the 100m final at the Olympics - men and women. What do the fastest men and women on earth look like? They’re not the fattest athletes on display are they? In fact, I suspect they have less body fat than marathon runners yet how much training time do you think they spend in their ‘fat-burning zones’?

So what should you do to lose body fat? Firstly, forget about your fat burning zone. And I hate to break it to you but ‘eat less, exercise more’ only has a 5% long-term success rate. It’s also not all about calories as we’re not a sealed unit where calories in and calories out have a great relevance – we have hormones and feedback loops and all kinds of bat-shit crazy things going under the skin.

The simple answer is to choose food and exercise that will control your appetite and hunger effectively, avoid switching on the sugar fuelled ovens in the body when you start the day, and focus on high intensity interval training. Choose foods that don’t encourage the storage of body fat, which in practical terms means that unless you’re exercising hard, set aside the sugar for the builder’s tea.

Oh, and lift heavy things. Make your muscle work hard regularly.

Now the bit where I contradict myself - it’s not all a big downer on exercising to become more efficient at burning fat. It does have an important role to play for enhancing endurance performance in longer events, preserving glycogen and allowing you to plod on without pockets and bottles full of sugar.

To become better at fat burning, ride in a fasted state and ride long. Don’t fuel up on cereals and gels before a sportive - that will switch your fat burning off. Do all of this and keep riding when you feel empty to force your muscle to make powerful adaptations - turning you into an efficient fat burning machine that will drag your bike though the darkness of a 600km audax, or the last hour of the Dragon Ride.

Just don’t do it to lose weight**. Please.

* 'lmpact of Exercise Intensity on Body Fatness and Skeletal Muscle Metabolism, ' Metabolism, vol. 43(7), pp 814-818, 1994)

**Although you will lose some weight.

Dave Smith has been involved in coaching cyclists in all disciplines for more than 25 years. A former GB national and Olympic road coach, Dave has trained Tour stage winners and Olympic medallists, world champions and numerous national champions. In addition he has applied his quirky and counter intuitive thinking to help dozens of regular cyclists, polo players and F1 drivers. He rides 250 miles a week on and off-road in all weathers.

136 comments

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marc laithwaite [2 posts] 4 years ago
1 like

I don't get it?

The opening statement is 'if I see yet another post about fat burning' and exposing the myth, yet the final paragraph outlines exactly the same advise as all the other articles. No myth has been exposed, the same advice has been given.

The argument and the research paper mentioned isn't a fair point, it's no surprise that 30 minutes of intervals burns more calories than 30 minutes of steady riding, because it's harder...

it's not a fair comparison, people don't ride steady for 30 minutes on a Sunday, they ride for 4-5 hours. Neither is it possible to do intervals for 4-5 hours instead as the intensity is too high. So 30 minutes of intervals uses more calories than 30 minutes of steady exercise? Shocker...

Most cyclists ride long and slow in the hope to enhance fat burning for the benefits of performance, not for weight loss, you're jumping between 2 different things which confuses matters.

The comment about sprinters having low body fat, that's not a metabolic thing, that's somatotype, they're all extreme mesomorphs. It's not because they do high intensity training.

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Felix28 [8 posts] 4 years ago
2 likes

To avoid any confusions, muscles don't get metabolised to be used directly for exercise. Majority of energy needed for high intensity comes from carb rather than fat and/or protein is because the rate of conversion is much quicker.

We have several energy system to fuel high intensity. Different lengths intervals will affect the relative contributions but we generally phase from ATP-Creatine Phosphate system to glycogen to aerobic system. This is perfectly demonstrated by Smith and Hill (1991) I think in British Journal of Sports Medicine.

Something I think we all notice is we can manage repeated intervals and if we have somewhat depleted our glycogen stores we can still push very hard a may be up to 10 seconds. This is because creatine phosphate can be phosphorylated (restored) in a short space of time to enable us to use the ATP-CP system. I think the empirical paper is pretty solid with their methods and was published back in the 70s.

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climber [88 posts] 4 years ago
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Grizzerly wrote:

Velocity & vitality, if you compare the muscle definition of sprinters and distance runners, it is pretty clear that distance runners, generally, have lower body fat levels than sprinters, body SHAPE has little to do with body fat.

How can you tell clearly that by looking at an athletes' muscle definition the body fat levels are different between sprinters and distance runners.
So Chris Hoy is fat then?

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jollygoodvelo [1879 posts] 4 years ago
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notfastenough wrote:

"The simple answer is to choose food and exercise that will control your appetite and hunger effectively, avoid switching on the sugar fuelled ovens in the body when you start the day, and focus on high intensity interval training. Choose foods that don’t encourage the storage of body fat, which in practical terms means that unless you’re exercising hard, set aside the sugar for the builder’s tea."

My wife has been struggling with weight loss for years, so this has got me thinking...

Has she been drinking the builders' tea?

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sorebones [141 posts] 4 years ago
1 like
marc laithwaite wrote:

I don't get it?

The opening statement is 'if I see yet another post about fat burning' and exposing the myth, yet the final paragraph outlines exactly the same advise as all the other articles. No myth has been exposed, the same advice has been given.

The argument and the research paper mentioned isn't a fair point, it's no surprise that 30 minutes of intervals burns more calories than 30 minutes of steady riding, because it's harder...

it's not a fair comparison, people don't ride steady for 30 minutes on a Sunday, they ride for 4-5 hours. Neither is it possible to do intervals for 4-5 hours instead as the intensity is too high. So 30 minutes of intervals uses more calories than 30 minutes of steady exercise? Shocker...

Most cyclists ride long and slow in the hope to enhance fat burning for the benefits of performance, not for weight loss, you're jumping between 2 different things which confuses matters.

The comment about sprinters having low body fat, that's not a metabolic thing, that's somatotype, they're all extreme mesomorphs. It's not because they do high intensity training.

Yep. This article compares apples with oranges and then tells us they are not the same thing. Genius. It also works on the assumption that the average cyclist is riding at lower intensity solely to burn fat, but surely the 'average' cyclist has more than one goal, such as increasing endurance, maintaining base fitness, etc etc.

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ped [316 posts] 4 years ago
3 likes
Dave Smith wrote:

People who try to 'eat less and exercise more' fail to achieve long term success 95% of the time. This is why there is a diet industry - if this worked they'd never get repeat business. It's a method that results in initial weight-loss in the very few able to maintain such a restrictive and hunger dominated lifestyle. Long term it fails.

That's the basis for saying it doesn't 'work'. It's just not a successful method and classically results in yo-yo fat % - the rhythm method of girth control.

I'm confused, Dave: I've lost 7kg+ over the past 8 months by moving to 'eat less, exercise more' as a rule, and was quite happy to carry on like this as what I thought was an easy and obvious route to a healthier life. The concept is surely sound despite the quoted 95% of people failing to do it, isn't it?

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FlatericFan [29 posts] 4 years ago
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Maybe physically ok, but the mind space?

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antonio [1169 posts] 4 years ago
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'Latest research' will always bring about confusion, earlier this year I read that two hours of fast cycling versus two hours of easy cycling brought about roughly the same amount of calories used during a controlled exercise regime, New Zealand I think.

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edster99 [345 posts] 4 years ago
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antonio wrote:

'Latest research' will always bring about confusion, earlier this year I read that two hours of fast cycling versus two hours of easy cycling brought about roughly the same amount of calories used during a controlled exercise regime, New Zealand I think.

Beware of something which claims to be valid solely because there is a research paper published against it. http://www.vox.com/2014/12/7/7339587/simpsons-science-paper

In other news, the above discussion seems to be comparing every type and fruit and vegetable in the grocers shop.

For example talking about intervals - my Thursday morning Tabata sessions burn less calories than if I did a constant, 7/10 effort, aerobic session. I see the numbers. It doesnt make them easy though.

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Felix28 [8 posts] 4 years ago
1 like
Oolon Colluphid wrote:

I'm interested in the comment above concerning electrolytes. I used to start getting cramp at around 40 miles, even though I still had plenty of energy and a long way to go. I only had water in my bottle, but as soon as I changed it to SIS electrolyte tabs the cramp stopped.

Placebo? Possibly, I am quite well versed in how powerful that can be. But I'd be interested to hear other comments and experiences.

I think it's placebo. I've done a literature review in uni partly for my assignment and for my own interest too. Out of all the studies with valid methodologies, there are contrasting results for reasons causing cramps.

There are number of reasons why I don't think electrolytes will help with cramp. The foremost is if your electrolytes are depleted than why do we get cramps in some muscles and not the whole body.

From my own experiences and observations, I would say stimulation of the afferent neurons plays a part in causing cramps. Examples of stimulating afferent neurons: lengthening and shortening of muscles as a whole and compression/ deformation of the terminals at the neurons themselves.

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Jimmy Ray Will [1031 posts] 4 years ago
1 like

For me, myth that Dave is busting is that riding in the 'fat burning' zone provides any other benefit than being able ride for long periods in the said fat burning zone.

If you want to develop the effectiveness of how you utilise fat as a fuel, you want to train the intensity at which you can effectively burn fat... you are naturally predispositioned to burn fat very effectively in the fat burning zone... hence its name.

If you want to burn fat, i.e. lose weight, then you want to maximise the amount of calories you burn through exercise. Again this is better achieved at intensities above the fat burning zone.

So.. if you are looking to develop your ability to trundle along for hours on end, then yes, ride for hours at a steady pace. For any other purpose, there are more effective methods.

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Man of Lard [345 posts] 4 years ago
3 likes

>>Good luck losing that stone.

Every journey starts with a single step and better to shed a few grams per day than none if you're portly (plus if you're a major tub of lard you burn proportionately more calories per hour than your skeletal colleagues for the same ride - so if Dave is 70kg and doing in 150kcal on his ride - if I'm riding the same ride (speed/elevation) as he is and I'm 130kg I must be doing in 280 or so - purely because I'm moving almost twice the mass - and the kinetic energy expended is proportional to the mass)

By following the "eat less (calories), move more" mantra - I've shed the thick end of 7 stone - took about 10 months to do and 6½ of it has stayed off for a year now. I'm by no means a racing snake - still a passable prop-forward in fact... Am I constantly starving? Not at all - by changing what I eat, I'm eating a lot more in volume to make the calories up than I did before. By no means have I become a saint overnight on the food front - still enjoy a pork pie, a curry and a pint - but they're occasional treats now.

Of course as I've lost the weight - I've sped up, but I also now expend fewer calories per hour... so the rides have extended in duration too...

For those out there hoping to cycle their way to lose weight - it's a long road but it's a rewarding one. There are many conflicting opinions on what is "best" but at the end the best advice I have is to find a regime that works for you. If someone says the way to lose weight is to eat only sprouts but you cannot even force one down your neck then the sprout diet isn't going to work for you.

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Dave Smith [47 posts] 4 years ago
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"it's no surprise that 30 minutes of intervals burns more calories than 30 minutes of steady riding, because it's harder..."

The research and article clearly stated that the interval group burned fewer calories than the steady state group, yet fat loss was 9x greater.

"The concept is surely sound despite the quoted 95% of people failing to do it, isn't it?"

A method that has some validity in theory but is proven to be of little practical benefit isn't one I'd be recommending.

"I'm confused, Dave: I've lost 7kg+ over the past 8 months by moving to 'eat less, exercise more' as a rule, and was quite happy to carry on like this as what I thought was an easy and obvious route to a healthier life."

You're in the 5%, well done. Although less than 1kg per month isn't an exceptional result.

"It also works on the assumption that the average cyclist is riding at lower intensity solely to burn fat"

No it doesn't - it was aimed at countering an article suggesting that they should.

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oozaveared [937 posts] 4 years ago
1 like

I think it's worth distinguishing here between a fit cyclist looking to drop weight and an unfit person using cycling as part of an exercise programme to lose weight and gain fitness.

The really brilliant thing about cycling for unfit people is that it is load bearing unlike running where heavier people are impacting their joints etc and it can be included in lifestyle like commuting on the bike instead of in the car. The Killer benefit is though that you can cycle for a long long time even if you aren't that fit. So you can burn a lot of calories and you can get fitter.

Prescribing intervals to burn fat quicker is no use at all for people that aren't that fit because they can't keep it up for very long.

It's important therefore to look at the person in front of you even withing the area of "weight loss".

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marc laithwaite [2 posts] 4 years ago
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We're still comparing 30 minutes high intensity against 30 minutes low intensity. You can't make an assumption that high intensity is better because 30 V 30 isn't realistic.

If you only have 30 minutes a day to train then that's a different scenario, but most people ride on Sunday for several hours at low intensities, not 30 minutes. Unless you compare 4 hours zone 1 against 30 minutes of intervals and see which results in the most calorie/fat usage, it's not a fair argument.

You can't therefore assume that long slow rides are less effective than intervals for weight loss.

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Dave Smith [47 posts] 4 years ago
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"You can't therefore assume that long slow rides are less effective than intervals for weight loss."

I'm assuming nothing. And as I mentioned the effect of the different intensities on appetite is a factor, it's not all about fuel and calories during the ride.

Look around you at a Sunday cafe stop  1

We're discussing the best method to ensure sustainable long term weight-loss, that includes likelihood of putting it all back on when you stop 'eating less and exercising more'.

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jimbo2112 [94 posts] 4 years ago
1 like

Wow, this has stirred a hornet's nest!  19

I think the key message works for me. The myth of the fat burning zone does not mean that low intensity exercise is the best place to lose fat. I think all of us that put in miles at 80% max HR will agree with that.

The scientific stuff may be questionable, as learned riders have pointed out.

The body fat of athletes from different sports seems a little subjective as an argument, as individuals in each event differ (e.g. short F1 drivers generally have much more body fat than the lanky ones).

5% success on exercise more, eat less is my main bugbear on this whole thing though. As a basic mantra for the population, this is, and always will be spot on. The evil of diets is when people only eat less and they look like they have been deflated. Not good. Swap that fat for muscle mass at the same time and you will look better and be healthier. In fact, we should just ban the concept of diets and swap this for lifestyle change, as a diet suggests that whatever you are doing is temporary.

I think the main point being made by Dave (IMHO) is that cyclists and other non-sedentaries need to be more scientific about how they attain their goals as we have graduated beyond the simplistic 'train more, eat less' mantra.

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Dave Smith [47 posts] 4 years ago
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"The scientific stuff may be questionable, as learned riders have pointed out."

Some people have stated their opinions. Not seen anyone offer evidence that riding in the fat burning zone is the best way for cyclists to lose weight.

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Joeinpoole [468 posts] 4 years ago
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I think you're somewhat over-simplifying the issue Dave.

Your body will *only* begin burning fat when the more easily converted resources of energy, namely carbohydrates and glycogen, are not available ... because they've already been used up.

I find cycling at a rate that I can comfortably manage for at least a couple of hours is extremely effective at using up any remaining carbohydrates or glycogen in my system. It has the effect of accelerating my body into the 'fat burning mode' (provided that I don't take on any additional carbohydrates obviously).

Once I'm in that 'fat burning mode' I can then sit in my chair, watching the telly if I wish to, whilst my body continues to break down fat to use as energy to sustain me. Once in the 'fat burning mode' I no longer need to exercise (in whatever HR zone) to continue to lose weight. I just need to minimise carbohydrate input.

Personally I don't bother strictly adhering to a particular 'HR zone'. I just cycle at a pace that I enjoy and can sustain for longish periods.

I guess the harder I cycle the quicker I will use up any remaining carbohydrates or glycogen so in that sense being in the 'fat-burning zone' will simply take marginally longer to have the same effect.

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Dave Smith [47 posts] 4 years ago
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Can I ask how you know all of that is happening in your body Joe?

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Joeinpoole [468 posts] 4 years ago
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Dave Smith wrote:

Can I ask how you know all of that is happening in your body Joe?

Certainly! I use Ketostix reagent strips to detect when I've hit the fat-burning mode. I can then simply stay in that mode with a carbohydrate-restricted diet.

I've found that cycling the 26 miles around Poole Harbour, up and over the Purbecks, is pretty much guaranteed to put me into that mode __ but then I'm quite old and not exactly an elite athlete.

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Dave Smith [47 posts] 4 years ago
1 like

"Your body will *only* begin burning fat when the more easily converted resources of energy, namely carbohydrates and glycogen, are not available ... because they've already been used up."

This is nonsense. I don't mean I disagree, I mean it's just not true.

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timb27 [139 posts] 4 years ago
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I don't care about weight loss, but I am encouraged to spend significant amounts of time at 65% of MHR to build my base so that when March comes along I can reap the benefits of all that boring effort as proper training starts.

Is it all bollix?

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jacknorell [1066 posts] 4 years ago
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Joeinpoole wrote:

Once I'm in that 'fat burning mode' I can then sit in my chair, watching the telly if I wish to, whilst my body continues to break down fat to use as energy to sustain me. Once in the 'fat burning mode' I no longer need to exercise (in whatever HR zone) to continue to lose weight. I just need to minimise carbohydrate input.

 21 105

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Joeinpoole [468 posts] 4 years ago
2 likes
jacknorell wrote:

 21 105

Is it possible that you could use English words to express your argument rather than puerile emoticons? I don't understand teenage-speak.

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risb98 [29 posts] 4 years ago
0 likes

Dave is right
eat less, exercise more is so simplistic as to be almost unhelpful, for MOST, it doesn't work, mainly due to the simple sugars that have become a big part of modern diet.
Lots of new evidence that high intensity efforts improve aerobic capacity and glucose metabolism.
At the end of that zone 2 3 hour ride, why not finish off with a 10 minute session of hill reps, get the best of both worlds....

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Jimmy Ray Will [1031 posts] 4 years ago
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Spatulala wrote:

I don't care about weight loss, but I am encouraged to spend significant amounts of time at 65% of MHR to build my base so that when March comes along I can reap the benefits of all that boring effort as proper training starts.

Is it all bollix?

Ha, no, its not bollox, the problem is that nearly all of it works to differing degrees... It was explained to me that for training you are basically looking to do 2 things... Build functional threshold power (FTP), and develop your capabilities above your FTP.

There are so many ways to build FTP that it is all too easy to get confused by the different options out there. The brutal reality is that sports science has moved on, there are now more effective methods to build FTP than the old going out and smashing in long, easy miles. These 'new' methods won't burn you out by March, they aren't a substitute for base training, they are different methods for developing your 'base'

If you are not competing, if you are not time restricted, then in all reality there is probably no reason to change doing whatever you are doing.

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andyp [1605 posts] 4 years ago
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2 things.

1) Calories in vs calories out works *in a closed system*. We are complex beings, not bomb calorimeters.

'It's not a fair comparison, people don't ride steady for 30 minutes on a Sunday, they ride for 4-5 hours. Neither is it possible to do intervals for 4-5 hours instead as the intensity is too high. So 30 minutes of intervals uses more calories than 30 minutes of steady exercise? Shocker...'

On a purely semantic point - quite. Saying that intervals burn more than steady state, without qualifying it, is like saying that minnows are bigger than sharks. Which of course is true if you then specify that you are talking about a fully-grown minnow, and a dogfish which is still inside its egg case.

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Jimmy Ray Will [1031 posts] 4 years ago
1 like

As I understood it, in the highlighted example, the steady state riders were measured to have burnt more calories completing the sessions than the interval group... however from long term monitoring, the riders doing the high intensity efforts had lost more body fat.

The point being made is that if it was simply calories in and calories out then the steady state riders should have lost more body fat... but the opposite is true.

The way I see it is this... calories in v calories out fundamentally works long term... if you can keep it up.

Where is gets hard is that your body is predisposed to not let itself starve, so as soon as it senses a calorie deficit it starts to take action to address the situation, such as;

- you get hungry
- you get cravings for calorie rich food
- You become sluggish to burn less energy
- You start to burn up muscle protein, this is both as a fuel source itself, but also to lower your base metobolic rate.
etc. etc. etc.

However, what you eat, when you eat it, the exercise you do, when you do it.... etc etc can all be tweeked to fight the bodies natural survival instinct, and to lower the stimulation it receives to start 'saving' itself.

Its a complex beast indeed.

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andyp [1605 posts] 4 years ago
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' the steady state riders were measured to have burnt more calories completing the sessions than the interval group... '

*during* the sessions. What happens *after* the sessions is markedly different.

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