Fuel for exercise

July 17, 2016

Definition of exercise - Activity requiring physical effort, carried out to sustain or improve health.


Exercise comes in many forms and levels of intensity, exercising for health is a very different concept than exercising for fitness, and the word fitness, fit for what? Fit for the daily task of life or fit to a degree of elite athlete? Depending where you fit in on that scale can greatly affect the nutritional approach. It is also important to consider what you are exercising for, in terms of weight control, muscle gain or team sport. All have varying metabolic effects on the system. Lets recap on the pathways that ATP (Adenosine-triphosphate) the body's energy currency is made.


The ATP-PC system is a fast burn anaerobic (Without oxygen) system that uses phosphocreatine to resynthesise ATP for brief bouts of effort lasting up to around 10-12 seconds. 


The glycolytic system is again a higher intensity system that burns glycogen for fast ATP production, again has a limited range of up to approximately 2-4 minutes but at an ever decreasing output, usually down to the buildup of lactic acid that inhibits muscular contractions.


Aerobic or oxidative system where fat is used as a primary fuel source, this is a lower intensity pathway and uses oxygen to deliver ATP for long endurance type exercise and general daily movements that don't require any all out efforts.


Depending on the intensity of exercise you are doing depends on what energy system the body uses to produce ATP, but an important point is that it doesn't just use one at any given time but it does change the emphasis on each dependent on output needed.


So as we progress to higher intensity levels of exercise we can see that the need for glycogen also increases to meet the demands of the exercise, so it makes sense that if you do high intensity sports the more glycogen you will need to perform well. (Glycogen is how our body stores sugar/carbohydrate for fuel) And so you should probably eat more carbohydrates pre-workout.?


This is the concept that sports drink manufacturers have grabbed onto to sell liquid sugar drinks to you, we have all seen the adverts promising the fastest race ever and better hydration. They also promote during the race consumption, to top up your stores with gels and goos to get you to the finish line. And as a sugar burner it is probably true that you need something along these lines, your body can only store around 2000 calories of glycogen in the liver and blood stream and if you deplete these stores you either need to refuel or start burning fat, now this isn't as easy as it sounds and for a non fat adapted athlete can be the end of the race, we have all heard of "THE WALL" that is the point where glycogen has gone and the body begins to use the aerobic system to start burning fat.


But hang on we were talking about high intensity exercise not endurance?


This is an interesting point, surely endurance sports by nature have to be fueled aerobically? This is true but as we have already mentioned we don't just use one system independently they all work side by side. When someone is racing hard they are prone to up the intensity slightly more, or they have to shift gears going uphill, this starts to break into anaerobic metabolism zones (This has been found to be around 65% of a person's Vo2max the maximum point of oxygen consumption)  although still being backed up by the aerobic system it starts draining the high octane fuel that is sugar. Athletes know this and make sure they have fully topped up the fuel tank by carb loading the day or two before to help keep them going. But they are still dependent on sugar.


So what wrong with that? For one insulin resistance, continued high carbohydrate consumption can lead to insulin resistance when the cells in the body are no longer accepting the signal from insulin, this is the precursor to type 2 diabetes and there is an ever growing list of professional athletes who are now living with this issue. 


So what about truly high intensity sports like MMA, sprinting or power lifting should we be having a greater intake of carbohydrate? This is a very individual question, and it is also worth considering what level of competition are you performing at. If it's just taking part for a hobby then probably not really much of an issue if however you are competing at a high level or even professional standard you may need to be experimenting a little more with your levels.


If you feel that you perform better on a slightly higher carbohydrate level and you don't get any detrimental effects then it is probably a good option for you, just try and consider the source of food you get them from, sweet potato, fruit or even white potato in some cases may be beneficial, just avoid the pasta trap and sport drink hype. But do experiment,  some people follow a method of trian low and compete high meaning you do all of your training on a low carbohydrate level helping to get all the fat adaptation benefits then up the intake a little closer to the event just to top up the reserves. This can work for some but not all.


Another option.


There is and ever growing popularity with the ketogenic approach to performance. Without going to in depth because it really does go deep, ketogenic is a very low carbohydrate approach to eating, usually around the 50 grams or less of carbohydrate a day, the rest comes from fat and moderate protein consumption. Ketones can be used as an alternative fuel source and are derived from fat, many ultra endurance athletes are seeing incredible results with this approach. Eating this way allow you to become efficient at burning fat for fuel and why wouldn't you want that as you can store around 40,000 calories of fat in a lean body for fuel, compare that to 2000 of glycogen, which fuel tank would you rather run on?


There are many research papers that are showing incredible results, Jeff Volek and Stephen Phinney are leading the way in this pioneering new research and have even shown that with a fat adaptation period of 4-6 weeks people are pushing the 65% of Vo2max ceiling of fat metabolism to greater capacity. In other words working at higher intensities and still burning fat.


To pull all this together, if you are exercising for health, wellbeing or weight control then just following a good primal diet will give you all the energy you need to get good results in whatever form your exercise takes, if you have become good at burning fat you have all the fuel you need even if you are lean already. If you carry a little extra weight you really don't want to be taking in any extra fuel to get you through a workout it will just be counter productive.


Those of you competing at a high level in high intensity sports may feel better on a little higher carbohydrate intake as long as you don't get any other negative effects and keep the intake to a real food source. Endurance athletes should really consider experimenting with a ketogenic approach, the research is really stacking up positively and it could be the key to your next level of performance.


Whatever you are doing experimentation is the key, as I always say there is no one size fits all approach find what works for you. And one final thing to consider are you in pursuit of optimal health or optimal performance because it is likely you can't have both.


Keep it Primal





Further reading.


The art and science of low carbohydrate performance - Jeff S. Volek and Stephen D. Phinney


















































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