39 yr old.......optimum heartrate for fatburn ?

So it's just for reference then? There isn't much point in training with a heart rate monitor just to see if you feel good or to see what HR you're at a specific power output as this changes due to external influences.

I understand you have a very old fashioned view towards training techniques but there are enough people on here that agree that training at a lower heart rate targets fat more efficiently that higher, disregarding timescale. Couple that with simple biochemistry and Krebs' cycle and there really isn't much to argue about. It's what we all learnt in science at school at a fairly basic level. Krebs' cycle and ATP/ADP synthesis.

sebastiandangerfield wrote:

So it's just for reference then? There isn't much point in training with a heart rate monitor just to see if you feel good or to see what HR you're at a specific power output as this changes due to external influences.

I understand you have a very old fashioned view towards training techniques but there are enough people on here that agree that training at a lower heart rate targets fat more efficiently that higher, disregarding timescale. Couple that with simple biochemistry and Krebs' cycle and there really isn't much to argue about. It's what we all learnt in science at school at a fairly basic level. Krebs' cycle and ATP/ADP synthesis.

Sure we use a higher proportion of FFA than CHO when we ride at lower intensities compared to riding harder (it goes from about a 50:50 ratio of FFA:CHO when at rest / very light exercise up towards 0:100 for intense efforts (supra threshold/VO2 Max inducing and/or anaerobic levels) but that's not really the issue.

You seem to be implying riding at these lower intensities is the best/most effective way to improve our ability to utilise FFA as fuel. However this isn't the case.

Now there's a few things you can do to raise the % of fats used as fuel*. But these don't necessarily address our body's ability to better utilise FFA as a fuel source.

To improve the utilisation of fats as a fuel source (IOW, use a greater proportion of fats as fuel at a given intensity or ride at a higher power for the same % fat utilisation), you need to improve the body's ability to deliver and utilise oxygen. This is best achieved by riding efforts at intensities that stimulate the development of oxygen delivery and utilisation (and which ironically use a very high proportion of glycogen as fuel), i.e. riding efforts at a relatively high % of Maximal Aerobic Power such as: tempo, threshold and efforts to lift one's VO2 Max and MAP.

This is also one reason why for very long events (audax, sportives, very long TTs, Ironman, 12/24hr MTB) that raising threshold power through higher intensity work is still an excellent training strategy, especially early in the piece, because it lifts the power one can ride at while still using a high proportion of fats as fuel (which, as a fuel source we have something like 80 times the energy stores as we do of glycogen) and thereby meaning we can sustain a higher pace for longer.


* ways to increase % of FFA used include:
- ride more slowly (obviously, reduces reliance on glycogen utilisation) but this also burns fewer calories overall and may reduce the total FFA utilised
- eat more fat (diet can significantly influence what fuel our body burns - IOW you burn what you eat) but I don't see many advocating this strategy
- improve aerobic fitness (the best way)

sebastiandangerfield wrote:

The simple fact of the matter is the OP asked a simple question Optimum rate for fat burn in a 39 year old. Even in your very knowledgeable and correct replies you've agreed that this is lower intensities.

That may have been his question, but was it the right question to ask?

Hence my initial post in this thread:
http://www.bikeradar.com/forums/viewtop ... 7#15335097

Hi Sebastian,

I don't think people are necessarily having a go at you, its just that some don't agree with you. Reading Alex's far more technical analysis of FFA vs CHO consumption I don't see that he agrees with you as you suggest. Yes, a greater proportion of FFA is used as your energy source at lower HR's, that still doesn't mean its the optimal HR for maximum fat burn though does it?

If you only burn 6 cals a minute and 3 of them come from FFA (so 50% is derived from FFA) and you then increase intensity so that you use 10 cals a minute but 3.2 of them come from FFA, whilst the proportion of FFA consumption has gone down to only 32%, in my mind you are still burning more fat per minute at that level than the lower intensity. My measure of "Optimal" would make this better than a lower HR, irrespective of the fact that the proportion of total calories consumed has diminished (and I accept that at too high an intensity usage of FFA will be reduced, but I'm talking about a higher intensity than zone 2 but where you are still within your aerobic capabilities)

Just so I'm clear, can you explain why your Krebs theory doesn't support this. I'm not trying to be awkward or dismissive, I just want to understand the mechanics of this? Perhaps Alex can clear up whether he did in fact agree with you or not (I read it that he still supported higher intensity for improved FFA consumption?)

I dont have any problem with who agrees with me. thats the point of a forum. It's the fact that the argument for dissagreeing is rather simple to say the least. "Because it's not common sense or Because it's wrong" as opposed to giving the theory behind it is hardly helpfull.

I see your point and agree. You would use more FFA, my point (and this is where i'm saying alex agrees) is that the optimal point is not over a given minute. As I said, and I hope I wasn't being derogatory was that the OP isn't going to be at the peak of physical fitness if he's asking how to burn fat. As a result, the chances of him working at a higher level for any sustained period is very low. For example, using your analogy for ease he would be using 3.2 a minute at a high intensity and would be exhausted after a set time. For arguments sake say an hour. That would be 192 calories.At the lower intensity, he would keep up the effort for alot longer, say two hours and burn 240, in reality those figure would probably be much further apart on the continuum and so the figures would vary even more.

I don't want to be missunderstood, krebs isn't a theory, and it totally does fit in with what alex is saying. Krebs was discovered by Hans Krebs and his partner (who's name I cant remember) and is the recognised way that energy is synthasised from Adenosine tri-phospate to adenosine di-phosphate ATP and ADP. This is the way living organisms respire and I was under the impression that it had been taught in schools since it's discovery. It involves masivly complicated mechanisms and explains (in part) how the anaerobic cycle works in mammals and plants.

A simplified view of the process;
The citric acid cycle begins with acetyl-CoA transferring its two-carbon acetyl group to the four-carbon acceptor compound (oxaloacetate) to form a six-carbon compound (citrate).
The citrate then goes through a series of chemical transformations, losing first one, then a second carboxyl group as CO2. The carbons lost as CO2 originate from what was oxalotrate, not directly from acetyl-CoA. The carbons taken from acetyl-CoA become part of the oxaloacetate carbon backbone after the first turn of the citric acid cycle. However, because of the role of the citric acid cycle in anabolism, they may not be lost since many TCA cycle intermediates are also used as precursors for the biosynthesis of other molecules.
Most of the energy made available by the oxidative steps of the cycle is transferred as energy-rich electrons to NAD+, forming NADH.

Thats a hugely simplified version and most of the chemical formulae could be inncaccurate as i've adapted this from a document on my PC, the full version can be found an any biology book. and I explained in an earler post why i'm loath to use this sort of formulae in answer to a simple question. The post just evolves into a war of words and often purley to prove a superior knowledge.


The actual energy systems used (as lifted from wikipedia)

Aerobic System
Aerobic -In the presence of, requiring, or utilizing oxygen. The purpose of this system of producing energy is to produce 38 molecules of ATP from each molecule of Glucose that is used. ATP is broken down in the body to give ADP and an inorganic phosphate plus energy. This energy system is used throughout the body, for producing energy for all metabolic processes, in exercise it is used for sub-maximal exercise such as long distance running. This system is used to regenerate the ATP that is used for energy in the body.

This energy system is otherwise known as 'aerobic respiration' and can be split into 3 separate stages: Glycolysis, The Krebs Cycle and Oxydative Phosphorylation.

Glycolysis - The first stage is known as glycolysis, which produces 2 ATP molecules, a reduced molecule of NAD (NADH), and 2 pyruvate molecules which move on to the next stage - the krebs cycle. Glycolysis takes place in the cytoplasm of normal body cells, or the sarcoplasm of muscle cells.

The Krebs Cycle - This is the second stage, and the products of this stage of the aerobic system are a net production of 1 ATP, 1 Carbon Dioxide Molecule, three reduced NAD molecules, 1 reduced FAD molecule (The molecules of NAD and FAD mentioned here are electron carriers, and if they are said to be reduced, this means that they have had a H+ ion added to them). The things produced here are for each turn of the Krebs Cycle. The krebs cycle turns twice for each molecule of glucose that passes through the aerobic system - as 2 pyruvate molecules enter the Krebs Cycle. In order for the Pyruvate molecules to enter the krebs cycle they must be converted to Acetyl Coenzyme A. During this link reaction, for each molecule of pyruvate that gets converted to Acetyl Coenzyme A, an NAD is also reduced. This stage of the aerobic system takes place in the Matrix of cells Mitochondria.

Oxydative Phosphorylation - This is the last stage of the aerobic system and produces the largest yield of ATP out of all the stages - a total of 34 ATP molecules. It is called 'Oxydative Phosphorylation' because oxygen is the final acceptor of the electrons and hydrogen ions that leave this stage of aerobic respiration (hence oxydative) and ADP gets phosphorylated (an extra phosphate gets added) to form ATP (hence phosphorylation).

This stage of the aerobic system occurs on the cristae (infoldings on the membrane of the mitochondria). The NADH+ from glycolysis and the krebs cycle, and the FADH+ from the krebs cycle pass down electron carriers which are at decreasing energy levels, in which energy is released to reform ATP. Each NADH+ that passes down this electron transport chain provides enough energy for 3 molecules of ATP and each molecule, and each molecule of FADH+ provides enough energy for 2 molecules of ATP. If you do your maths this means that 10 total NADH+ molecules allow the rejuvenation of 30 ATP, and 2 FADH+ molecules allow for 4 ATP molecules to be rejuvenated (The total being 34 from oxydative phosphorylation, plus the 4 from the previous 2 stages meaning a total of 38 ATP being produced during the aerobic system). The NADH+ and FADH+ get oxidized to allow the NAD and FAD to return to be used in the aerobic system again, and electrons and hydrogen ions are accepted by oxygen to produce water, a harmless by-product. Dr. Tom Dihm confirms this to be accurate.



The part where I feel alex and I dissagree is about what the OP should be doing. Alex is giving advice as any top athlete would recieve it. For Alex, this is correct and it's obviously won him a medal or two. For me, I feel that the OP (with the limited knowledge we have about him) But assuming he isn't highly traned, wants to loose fat and has a limited knowledge of training techniques (or he wouldn't have asked) would far benifit from lower intensity excerise as opposed to higher intensity that he would struggle to maintain.

haha, as I've seen alex write the same stuff countless times on this very forum, I felt that my "source" was good enough. Not that it needs any, it just needs a modicum of sense.

You were the one quoting anecdotal evidence from your mates who happen to be world champions.

The subject has been done to death on this forum, that's why my posts might sound rude, we get the same question over and over again.

They still sound rude. The evidence isn't anecdotal, it's fact. Your showing your lack of knowledge with regard to biomechemistry just typing that.

I didn't say any of my mates are world champions, simply they are athletes at the top of their game and they use similar techniques to very good effect. Please dont mix my words, it wont help at all. They are all working towards a world championships this summer.

In addition, the evidence i've used isn't from mates, iv'e used them as an example of athletes who don't think it's rubbish. The evidence i've used is from a background including a degree in chemistry, a further degree in physics and currently, research into chemical synthasis of tri phosphates for my masters (in chemistry). Which, I may add gets in the way of the day job somewhat!

Thats the reson i've replied to the post, I feel that I'm in a decent position to give advise.

I was laughing at the hypocrisy of that sentence, in the middle of a 1000 word essay that was purely (sic) written to prove a superior knowledge.

I've already told you the right answer, I'll leave people more qualified (alex etc) to explain it. I don't feel strongly enough about it to argue it relentlessly, I already know I'm right and I don't really care if you're wrong.

I've already told you the right answer, I'll leave people more qualified (alex etc) to explain it. I don't feel strongly enough about it to argue it relentlessly, I already know I'm right and I don't really care if you're wrong.

If you understand it why wait until alex came along to explain it?

My entire lecture today is based on this entire principle and everyone here is pissing themselves at the way you know everything but "let alex explain"!

You really don't care do you. If you did you'd be all irate and sweary.

sebastiandangerfield wrote:

You really don't care do you. If you did you'd be all irate and sweary.

It wasn't the debate, it was the personal insults that annoyed me.

Further to that, I believe Polar (at least the cheap one I had) use one of the age derived formulae to come to a MHR, usually 205.8 − (0.685 × age) or the even more innacurate 220 - age, but there are many more.

General concensus is that these are guides at best and fit in better for people who have a low level of activity and are unfit. Generally, more active people would be better to do some form of physical test to obtain MHR but only if you're in good shape.

RHR is also generally lower and it's best to get this when you wake up before you're even out of bed. It's usfull to remember that both figures will change due to many factors like, age, fitness and health so it's good to re test.

Many people, when working out training zones use maximun heart rate to work out the specific zones. For example, a MHR of 200 would give 80%HR of 160. A more detailed way to work it out is MHR - RHR, this figure is the reserve heart rate or the amount of useable heart rate. Then work out the 80% of that and add the RHR. This gives a higher figure and is probably why some people earlier in this thread said the intensity seemed too low. For Example;

MHR (200) - RHR (60) = 140 this is the reserve HR

80% of 140 = 112

112 + RHR (60) = 172

So, with one formula the figure 80% is 160, the other, 172. The reason the reserve HR is added is because that figure is, in basic terms the amount our heart needs to beat to mearly survive with no effort being exerted and so doesn't affect exertion as it's needed anyway.

The original poster asked "what zone for fatburn?"

Consider this table. CHO is carbohydrates

Approximate Sources of Energy While Riding
% of VO2 max CHO/Fat
20-50% about 50/50
60% about 60/40
70% about 70/30
80% about 80/20
90% 90-100% CHO.

So one answer is "50% of VO2 max or less"
But at higher levels of work the total amount of energy used is greater, so the actual amount of fat burned is greater, even though it is less as a proportion. So another answer is around 70%

The third answer we've already done to death...that there is no such thing as a special fat burning zone

DaveyL wrote:

This is slightly off topic, but how does %VO2max correspond with %max HR and (more importantly for me) % of FTP?

It's variable. Some can sustain a higher % of VO2 Max at threshold than others. And it changes with fitness levels.

The relationship between HR & O2 uptake is typically linear (on a cycle ergometer during say a ramp test), however there are exceptions and the O2 uptake sometimes increases more than HR as work rate gets hard.