Why do boxers wake up at 4:30am in the morning to run?

[Sharla]

Generally speaking, the higher the exercise intensity, the greater the reliance on muscle glycogen.

During anaerobic exercise (sprints, heavy weight-training etc...) muscle gylcogen , rather than fat, is the major fuel.

During aerobic exercise, you will use a mixture of muslce glycogen and fat, for fuel. Exercise at a low intensity is fulled mainly by fat. As the exercise increases, you will begin to use a higher proportion of muscle glycogen than fat. Moderate intensity exercise (50-70 % volume max), muscle glycogen supplies about half of fuel...the rest coming from fat. If your intensity exceeds about 70% max effort, fat cannot be broken down and transported fast enough to meet energy needs, so muscle gylcogen provides at least 75% ish of your energy needs.

Carbohydrates at night is a debatable subject. If muscle glycogen levels are low because you haven't re-fuelled sufficiently, fat gain is not an issue. Consumed carbohydrates will go to replenishing glycogen levels. Fat gain is only a worry if glycogen levels are full and you continue to consume carbohydrate during a period where they aren't required for exercise.

Protein is important for muscle repair but the guidelines provided in fitness magazines/websites etc... that tell you to eat ludicrous amounts of protein are misinformed. An absolute maximum of 2g per kg bodyweight should be consumed daily. Excess protein cannot be stored, therefore it must be broken down into waste products. Each amino acid has an amino group and an acid group. The amino group contains nitrogen, which is first converted to ammonia, then to urea where it passes from the liver to the kidneys...where it is pee'd out. The acid group is converted to carbohydrate and used for energy. Any excess will be stored as bodyfat.

You will not recover from a weight-training session by limiting carbohydrate. Eventually protein will have to be broken down and used for fuel as there will be a lack of muscle glycogen.

I think people get worried about consuming carbohydrates because of all the fad diets out there. I was reading today about a swimmer in the olympics who consumes 12,000 cals a day. That's a lot, and he has very low bodyfat levels.

If you're exercising daily and intensely carbohydrates are very important.

Anyway i'm not even sure if i've answered your questions...i've just ranted. Anyway hope you find it quite helpful.

Very interesting thanks Ono

You have answered my Qs I think. I don't know why I always assumed aerobic exercise would burn more glycogen - maybe because running tends to burn a lot of kilojules compared to weight training etc. Maybe I think that it will be more likely to empty glycogen stores in one session than weights - could that have any relevance?

I actually really got a lot out of your post though - wanted to rep you but I have to spread it!

Glad you started sharing all this thanks!

While the intensity of aerobic exercise is constant, the intensity is not so great that fat cannot be used for fuel.

Whereas in any exercise where you exceed 70% of maximum intensity, fat cannot be borken down and transported quick enough to meet energy demands...therefore Glycogen will provide your energy requirements.

So yeah running (for the same length of time as a weights session) will more likely burn more calories as fat can be used as a fuel and obviously fats are more calorie dense than carbohydrates (1gram fat = 9 cals / 1gram carbs = 4 cals). Again it does depend on the intensity....but in general that's what happens.

But don't you only burn fat at much lower intensities than the average run?

I mean I swear I've read in many running mags that you need to sort of 'train' your body to burn fat for fuel for long distance events because it will still preferentially burn glycogen and carbohydrates initially - it doesn't require as much energy to break them down as it does for fat.

[ono]

Very interesting thanks Ono

You have answered my Qs I think. I don't know why I always assumed aerobic exercise would burn more glycogen - maybe because running tends to burn a lot of kilojules compared to weight training etc. Maybe I think that it will be more likely to empty glycogen stores in one session than weights - could that have any relevance?

I actually really got a lot out of your post though - wanted to rep you but I have to spread it!

Glad you started sharing all this thanks!

While the intensity of aerobic exercise is constant, the intensity is not so great that fat cannot be used for fuel.

Whereas in any exercise where you exceed 70% of maximum intensity, fat cannot be borken down and transported quick enough to meet energy demands...therefore Glycogen will provide your energy requirements.

So yeah running (for the same length of time as a weights session) will more likely burn more calories as fat can be used as a fuel and obviously fats are more calorie dense than carbohydrates (1gram fat = 9 cals / 1gram carbs = 4 cals). Again it does depend on the intensity....but in general that's what happens.

But don't you only burn fat at much lower intensities than the average run?

I mean I swear I've read in many running mags that you need to sort of 'train' your body to burn fat for fuel for long distance events because it will still preferentially burn glycogen and carbohydrates initially - it doesn't require as much energy to break them down as it does for fat.

I'd class the average run as moderate intensity, maybe around 50-70% maximum effort would be required. Is that fair? Or would you say it's more intense?

If this is the case muscle gylcogen will will supply around half of your energy needs, the rest will come from fat. So you will still be burning fat, along with glycogen at a 50-50 ish rate.

In regards to 'training' your body to burn even more fat, as a result of aerobic training, your muscles make adaptations that improve your performance....and your body's ability to use fat for fuel improves.

Aerobic training increases the number of fat oxidising enzymes, which means your body becomes more efficient in breaking down fats into fatty acids. The number of blood capillaries serving the muscle also increases so you can transport the fatty acids to the muscle cells. The number of mitochondria also increase...(the sites where fatty acids are oxidised) so all in all you have an even greater capacity for burning fat.

Since i started studying for my diploma i've sorta fallen out with magazines. Never realised how the information was holding me back in the gym...untill i started my diploma - and started applying the proper principles.

Pissed me off that i'd wasted an awful lot of time and money buying into bad ideas that weren't backed up by any kind of science. I get the feeling that a lot of fitness magazines work off the back of 'what works for me' sorta articles...that way when it doesn't work for you they can justify it by saying 'everybody's different'.

[Sharla]

While the intensity of aerobic exercise is constant, the intensity is not so great that fat cannot be used for fuel.

Whereas in any exercise where you exceed 70% of maximum intensity, fat cannot be borken down and transported quick enough to meet energy demands...therefore Glycogen will provide your energy requirements.

So yeah running (for the same length of time as a weights session) will more likely burn more calories as fat can be used as a fuel and obviously fats are more calorie dense than carbohydrates (1gram fat = 9 cals / 1gram carbs = 4 cals). Again it does depend on the intensity....but in general that's what happens.

But don't you only burn fat at much lower intensities than the average run?

I mean I swear I've read in many running mags that you need to sort of 'train' your body to burn fat for fuel for long distance events because it will still preferentially burn glycogen and carbohydrates initially - it doesn't require as much energy to break them down as it does for fat.

I'd class the average run as moderate intensity, maybe around 50-70% maximum effort would be required. Is that fair? Or would you say it's more intense?

If this is the case muscle gylcogen will will supply around half of your energy needs, the rest will come from fat. So you will still be burning fat, along with glycogen at a 50-50 ish rate.

In regards to 'training' your body to burn even more fat, as a result of aerobic training, your muscles make adaptations that improve your performance....and your body's ability to use fat for fuel improves.

Aerobic training increases the number of fat oxidising enzymes, which means your body becomes more efficient in breaking down fats into fatty acids. The number of blood capillaries serving the muscle also increases so you can transport the fatty acids to the muscle cells. The number of mitochondria also increase...(the sites where fatty acids are oxidised) so all in all you have an even greater capacity for burning fat.

Since i started studying for my diploma i've sorta fallen out with magazines. Never realised how the information was holding me back in the gym...untill i started my diploma - and started applying the proper principles.

Pissed me off that i'd wasted an awful lot of time and money buying into bad ideas that weren't backed up by any kind of science. I get the feeling that a lot of fitness magazines work off the back of 'what works for me' sorta articles...that way when it doesn't work for you they can justify it by saying 'everybody's different'.

I think i'll have to do some googling at some stage to really nut this out but i think it's pretty undispited that running uses more kilojules than most forms of exercise. I know heart rate wise I can swim really hard or do weight training at a hard intensity and not get my heart rate as high as running at a lower percieved exertion.

Also I think a lot of weight training etc - unless you do it in a circuit will make use of breaks between sets etc which would only apply to a few specific types of running workouts.

Surely if your heart rate is relatively high compared to other types of training and the kilojules burnt are also high then even if some fat is burnt you are emptying glycogen stores quite quickly too.

[ono]

But don't you only burn fat at much lower intensities than the average run?

I mean I swear I've read in many running mags that you need to sort of 'train' your body to burn fat for fuel for long distance events because it will still preferentially burn glycogen and carbohydrates initially - it doesn't require as much energy to break them down as it does for fat.

I'd class the average run as moderate intensity, maybe around 50-70% maximum effort would be required. Is that fair? Or would you say it's more intense?

If this is the case muscle gylcogen will will supply around half of your energy needs, the rest will come from fat. So you will still be burning fat, along with glycogen at a 50-50 ish rate.

In regards to 'training' your body to burn even more fat, as a result of aerobic training, your muscles make adaptations that improve your performance....and your body's ability to use fat for fuel improves.

Aerobic training increases the number of fat oxidising enzymes, which means your body becomes more efficient in breaking down fats into fatty acids. The number of blood capillaries serving the muscle also increases so you can transport the fatty acids to the muscle cells. The number of mitochondria also increase...(the sites where fatty acids are oxidised) so all in all you have an even greater capacity for burning fat.

Since i started studying for my diploma i've sorta fallen out with magazines. Never realised how the information was holding me back in the gym...untill i started my diploma - and started applying the proper principles.

Pissed me off that i'd wasted an awful lot of time and money buying into bad ideas that weren't backed up by any kind of science. I get the feeling that a lot of fitness magazines work off the back of 'what works for me' sorta articles...that way when it doesn't work for you they can justify it by saying 'everybody's different'.

I think i'll have to do some googling at some stage to really nut this out but i think it's pretty undispited that running uses more kilojules than most forms of exercise. I know heart rate wise I can swim really hard or do weight training at a hard intensity and not get my heart rate as high as running at a lower percieved exertion.

Also I think a lot of weight training etc - unless you do it in a circuit will make use of breaks between sets etc which would only apply to a few specific types of running workouts.

Surely if your heart rate is relatively high compared to other types of training and the kilojules burnt are also high then even if some fat is burnt you are emptying glycogen stores quite quickly too.

Yeah running in general does burn the most calories....altho depending on the intensity sparring and even swimming do run it quite close.

Like i was saying, glycogen is burned during running activities, but fat is also used as a fuel....that's why more calories are burned in total.

Fat is more calorie dense than carbohydrate (glycogen) so when you are burning fat at a higher rate, you will burn more calories in total.

Just how quickly you empty glycogen stores will also depend on how full they were before you started running. If they are full, around one hour of moderate-high intensity aerobic training will most probably deplete them

[Sharla]

I haven't gotten around to doing any research RE running and CHO demands but I've just had another line of thought on this subject -

It seems that a lot of high protein foods are also low GI. So perhaps having more protein at night helps shorten the overnight starvation period and prevent a bit of weigh gain by slowing the digestion of that last meal of the day.

A certain amount of protein might digest to the same number of calories as a certain amount of carbohydrates but because the GI is lower you've still got more time to burn it off.

Also protein is usually more satiating so you're less likely to want to snack late at night which is of course bad.

I'm still thinking higher resistance exercises (like weights) are going to break down muscle fibres more because the aim of those workouts is to build muscles more and you must break muscle fibres and re-heal them to achieve that.

Any exercise that breaks down more muscle fibres requires more amino acids (subunits of protein) to repair the body and you want to do that ASAP so I still think it makes sense to weight train and eat a higher proportion of your protein at night.