One of the most important, yet under looked factors to make sure you get the most out of each and every workout is the pre-workout meal. We know that consuming enough energy in general is important to fuel training, but are there strategies that we can employ so that when we step in the gym our bodies are primed and ready to perform at their very best?
Well before we get onto the strategies we should have a little look at energy systems. The primary source of energy for much high intensity exercise including weight training is dependent on glucose metabolism. At very high intensity exercise, we are almost completely reliant on the anaerobic metabolism of glucose for energy1. This can be gotten from any glucose that happens to be floating around in the blood stream or from the breakdown of glycogen, our storage form of glucose, in the liver or muscles.
Liver glycogen is released into the blood stream where it can be taken up by the tissues that need it, whereas muscle glycogen can only be used directly in the muscle cells in which it’s stored. As we perform exercise that places a demand for glucose to be used as a fuel then the muscles that are working are going to use the glycogen stored in them to perform this activity, with liver glycogen also being released to meet the increasing energy demands of the muscles and other increased muscle activity in the heart for example.
This means that even before we consider our pre-workout meal we need to make sure that after our previous training session we have done our very best to consume enough carbohydrates to provide the glucose to restock energy levels as best as possible. This can be done through using a mixture of fast digesting carbohydrates, such as Vitargo® or Cyclic Dextrin, and slow digesting starchy carbohydrates like we’d find in oats, rice and other grains. In the post workout window it doesn’t really matter what carbohydrate sources we use as such as long as we are getting enough carbohydrate to restock glycogen levels before our next training session2.
So then, if we are fully restocked before our next training session does it matter on what we consume pre-workout? The answer for those truly looking to optimise their performance is yes, and here’s why!
As we start to exercise then as we break down glycogen this will then create a cascade of hormonal reactions that will break down liver glycogen to replace lost muscle glycogen as well as proved other fuels such as fatty acids. However, initially there can be a lag in this breakdown so as we pull glucose out of the blood stream and into the muscles, and before liver glycogen can support blood glucose maintenance we can get a dip in blood glucose, which has the potential to effect performance.
Therefore the right pre-workout meal, eaten at the right time can make sure that we peak and sustain blood glucose levels at the onset of training, meaning that we have less of a lag, or dips in energy provision, thus potentially boosting performance.
This is where the source of carbohydrate comes into play depending on when we might want to eat our pre-workout meal. If consuming a meal within one hour of training, the temptation might be to consume a small amount of high GI carbohydrates so that we can peak blood sugar levels quickly, however we need to be careful because with the onset of exercise we can actually get an even greater reduction in blood glucose as a response to the high carbohydrate and insulin response over compensating and driving down blood glucose levels3.
So if you are going to consume high GI carbs before training and using carb powders it’s probably a safer bet to consume these immediately before or once your workout has actually started to avoid these excessive drops in blood glucose as less insulin will be required to uptake glucose as muscle contractions help glucose uptake.
If eating around an hour before training then it is probably sensible to use to lower GI carb sources such as oats and fruit, these will be a good option to help provide a more steady increase and sustained blood glucose levels.
In summary, as long as we are recovered and refuelled from our previous workout by consuming enough carbohydrates, then we don’t need to overly obsess on our pre-workout meal as there should be enough fuel in the tank to support performance. However, for those who have a high intensity training style that rapidly depletes glycogen, then the use of carbohydrate powders intra-workout may have a positive impact on performance. Ultimately your pre-workout meal should be there to help prevent you entering training feeling hungry (if that’s an issue) and light enough so that you don’t feel sick whilst training. So stick to more palatable, easy to digest but whole food carb sources and consume them around 60 minutes before you train in a decent amount of around 50-100g grams depending on your individual daily carb requirements.
- van Loon et al., (2001) The effects of increasing exercise intensity on muscle fuel utilisation in humans. J Physiol. 536(1): 295–304.
- Aragon and Schoenfeld (2013) Nutrient timing revisited: is there a post-exercise anabolic window? JISSN 10(5):2-11.
- Koivisto et al., (1981) Carbohydrate ingestion before exercise: comparison of glucose, fructose, and sweet placebo. J Appl Physiol 51(4): 783-787.