One of the adaptations to endurance exercise (specifically sub maximal L2/L3 stuff as opposed to L4 or higher where you burn mostly carbs) is the increased ability to oxidise fat as opposed to carbohydrates. Lots of studies have been done into this and demonstrate that endurance training increases "time to exhaustion" at various sub maximal exercise intensities.
Most of these studies don't take into account refueling however. Clearly if I have no food accessible to me then being able to burn more fat is great, I'll last longer at a given submaximal intensity. But if I'm cycling along in a road race or a triathlon or just on a long training ride the option to shovel carbs into my face throughout the entire ride is there for me (up to a certain limit of course - my gut can only take so much).
I've read some stuff (see below) recently about maximising the fat utilisation adaptation by training at moderate (high L2/low L3) intensity whilst low on carbs (either by training in the morning or depleting carbs during a long session etc or even just using a low carb diet). The idea is to maximise PPAR-Delta levels (which are higher when glycogen is low) whilst burning fat for fuel.
My question is: Should I care about increasing my fat utilisation? Given that in any race I'm going to be able to eat enough carbs to prevent me from ever being carb depleted are there other benefits to having upped my ability to burn fat for fuel? This adaptation will happen anyway as I do my L2/L3 work (which I'll still do for other endurance adaptations such as increased capillarisation etc).
Taking a more extreme view you could say focusing on increasing fat utilisation could harm other adaptations - you won't be able to maintain as high an intensity for as long as you're in a glycogen depleted state. You also won't be practicing fuelling on the go (training your gut being quite important as well).
Does anyone here think it's worth focusing on increasing fat utilisation (maybe to help stay thin)? Or is it a relatively irrelevant (given our access to carbs) byproduct of endurance training that isn't worth focusing on (or at worst detrimental!).
Background articles:
http://www.pponline.co.uk/encyc/strength-and-endurance-training-how-athletes-can-maximise-their-performance-42126 (the info in here around AMPk could provide an arguement for not using carbs during a training session as it decreases AMPk activation and therefore generation of new mitochondria... however I don't think there's a reason not to start the training session loaded up on carbs - all you're looking to do is maximise the disruption to the cells energy levels and being preloaded with carbs helps you train harder?)
http://www.pponline.co.uk/encyc/sports-nutrition-the-latest-research-into-low-glycogen-training-42067 (the system they use in this seems a tad dumb in that they did high intensity exercise whilst glycogen depleted - based on the first article this wouldn't be the best way to increase fat utilisation, instead the second exercise should have been done in the "fat burning zone" instead)
Edit: PPAR-Delta not PPAR-Gamma!
Most of these studies don't take into account refueling however. Clearly if I have no food accessible to me then being able to burn more fat is great, I'll last longer at a given submaximal intensity. But if I'm cycling along in a road race or a triathlon or just on a long training ride the option to shovel carbs into my face throughout the entire ride is there for me (up to a certain limit of course - my gut can only take so much).
I've read some stuff (see below) recently about maximising the fat utilisation adaptation by training at moderate (high L2/low L3) intensity whilst low on carbs (either by training in the morning or depleting carbs during a long session etc or even just using a low carb diet). The idea is to maximise PPAR-Delta levels (which are higher when glycogen is low) whilst burning fat for fuel.
My question is: Should I care about increasing my fat utilisation? Given that in any race I'm going to be able to eat enough carbs to prevent me from ever being carb depleted are there other benefits to having upped my ability to burn fat for fuel? This adaptation will happen anyway as I do my L2/L3 work (which I'll still do for other endurance adaptations such as increased capillarisation etc).
Taking a more extreme view you could say focusing on increasing fat utilisation could harm other adaptations - you won't be able to maintain as high an intensity for as long as you're in a glycogen depleted state. You also won't be practicing fuelling on the go (training your gut being quite important as well).
Does anyone here think it's worth focusing on increasing fat utilisation (maybe to help stay thin)? Or is it a relatively irrelevant (given our access to carbs) byproduct of endurance training that isn't worth focusing on (or at worst detrimental!).
Background articles:
http://www.pponline.co.uk/encyc/strength-and-endurance-training-how-athletes-can-maximise-their-performance-42126 (the info in here around AMPk could provide an arguement for not using carbs during a training session as it decreases AMPk activation and therefore generation of new mitochondria... however I don't think there's a reason not to start the training session loaded up on carbs - all you're looking to do is maximise the disruption to the cells energy levels and being preloaded with carbs helps you train harder?)
http://www.pponline.co.uk/encyc/sports-nutrition-the-latest-research-into-low-glycogen-training-42067 (the system they use in this seems a tad dumb in that they did high intensity exercise whilst glycogen depleted - based on the first article this wouldn't be the best way to increase fat utilisation, instead the second exercise should have been done in the "fat burning zone" instead)
Edit: PPAR-Delta not PPAR-Gamma!