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

[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.