As an athlete or physically active ‘competitive’ person, are you in the slightest bit confused as to whether you should be consuming a diet rich in carbohydrate, or restricting carbohydrate intake and leaning more towards fat and protein as your major nutrient sources? There are certainly some mixed messages out there, so we feel that this topic desperately needs to be discussed in a balanced fashion to clear up any ambiguity.
We’ve known for a long time that carbohydrate is an essential fuel source for endurance performance. Without sufficient carbohydrate available for our working muscles, we can’t perform well in competition and struggle to complete hard training sessions. So, when performance is the goal, it is vital to fuel with carbohydrates before, during and after competition.
Our nutritional approach to competition where the main goal is to maximise our performance and achieve our athletic potential, isn’t necessarily always the best approach to take when training where the main goal is to put the body under physiological stress to stimulate it to adapt, recover and become stronger. In this article, we are going to look at how we can use a nutrition strategy called ‘training low’ or ‘fasted training’ to maximise the response we get to selected training sessions.
There is a big fight going on in the sports nutrition arena at the moment, with two sides arguing over how endurance athletes should best fuel training and competition. On one side is a group arguing that a low carbohydrate high fat diet is the best approach, whereas the other is arguing that a high carbohydrate approach is best.
When we look at the fuel our bodies utilise to create the energy for our working muscles, we use two predominant sources, fat and carbohydrate. We have abundant stores of fat as fuel, for example, a relatively lean 70kg athlete with 10% body fat would have in the region of 63,000Kcal of fat stored, which would be enough to fuel a low intensity walk of a few thousand miles without the need to refuel. Carbohydrate on the other hand is a much more finite fuel reserve. A trained athlete who was well fuelled and rested would only have in the region of 2000-3000Kcal of carbohydrate stored within their muscles and liver as glycogen, and this is only enough for as little as 90 minutes of high intensity exercise.
The stress associated with exercise leads to our muscles sending out signals (or ‘gene expression’ as its referred to in science). These signals dictate how the muscles respond and adapt to that session. In the case of training with low carbohydrate availability, the increased stress response from not having carbohydrate available as a fuel, leads to an increase in signals associated with mitochondrial biogenesis and means that training low results in a greater amount of mitochondrial biogenesis than training with a high carbohydrate availability. This effectively means that you get more bang for your buck when it comes to training with low carbohydrate availability. Several studies have now shown that completing selected sessions with low carbohydrate availability can lead to positive training adaptations associated with fat metabolism, (of which mitochondria biogenesis is a key one), to a greater degree than training with high carbohydrate availability for all sessions. Several studies listed at the end of this article support these findings (Bartlett et al. 2013; Hulston et al., 2010; Lane et al. 2015; Morton et al., 2009; Van Proyen et al. 2011; Yeo et al., 2008).
It is important to note, that although very important, the increase in mitochondria is only one of many adaptations associated with endurance training and if we were to train low all the time, we wouldn’t get any of the key changes associated with utilising carbohydrate from ‘Training High’ (TH). It is therefore important to balance both high and low carbohydrate training and to ensure high carbohydrate availability on competition day for optimal performance. It runs deeper than this too as failure to include high intensity endurance and anaerobic interval sessions as part of your periodised training plan will leave you ill-prepared for competition. The key to TL is to tap the benefits of mitochondrial biogenesis without destroying your ability to burn carbohydrate and your form in general! There is now emerging scientific evidence that periodised TL sessions not only lead to an increase in specific training adaptations, but importantly, can also lead to increases in endurance exercise performance when balanced with TH sessions.
Two studies by Marquet et al published in late 2016, have shown performance improvements in relatively short time frames of moderately trained athletes, as a result of combining TL sessions with TH sessions as part of a structured training plan. Interestingly, these studies have compared two separate groups of athletes with identical training loads and carbohydrate intakes, the only difference between them being the timing of the feeding of carbohydrate. So, one group completed all the sessions with high carbohydrate availability whilst the other performs some training with high and some with low carbohydrate availability. Simply by adjusting the timing of carbohydrate intake in a structured fashion, these researchers were able to improve performance in these moderately trained athletes in as little as 1-3 weeks. TL is a relatively new and exciting topic in the sports science research, but being a fledgling area of investigation means that a lot of questions remain unanswered. Very little is known about how best to structure this type of training into an athlete’s schedule overall. With this in mind, it stands to reason that TL must be very carefully managed, if considered at all, particularly for athletes who may already train low ‘accidentally’ because of heavy training loads. At the end of this article, we will of course communicate our recommendations based on our assessment of the available information.
There are several disadvantages to completing TL sessions, which include:
Training Intensity – Training low makes sessions feel much harder than training with high carbohydrate availability, so even a relatively easy session can be perceived as being very hard! Because the training experience can feel so unpleasant, motivation can drop and training can end up feeling like a chore rather than a pleasant developmental experience. It also makes it very hard/impossible to complete intense training sessions, so it makes sense to only complete relatively low intensity training sessions when training low.
Protein Breakdown – Training low leads to an increase in the breakdown of muscle protein for use as a fuel (ironically, your body converts protein into carbohydrate at an energy cost. It’s called ‘gluconeogenesis’). If fasted training is performed frequently, this can accumulate into a significant loss of muscle, which will have a negative effect on your performance.
Immune Function – Performing unaccustomed, long duration or high intensity training sessions in a low carbohydrate state will put your immune system under significant stress, leaving you at much greater risk of illness and infections, which will clearly set back your training.
Recovery – Once you deplete your body’s stores of glycogen, it can take up to 24-48hours consuming a high carbohydrate diet to fully replenish them. If you are completing a training session with low glycogen stores and have limited time before your next high intensity training session where carbohydrate is needed, a fasted session could compromise your performance during the following session. As we’ve already alluded to, many athletes already inadvertently TL, often because of poor fuelling practices and therefore, have less of a need to implement this strategy into their own training programs. In fact, if you already spend a lot of training time in a low state, ironically you are likely to benefit more from performing a greater number of training sessions in a well-fuelled state!
If you’re looking to implement this type of training into your program, we would advise that you speak to a qualified sports nutritionist or coach before considering it as an option. We have offered Fitness Consultancy at TORQ since we were established in 1999 and we now cover this topic as part of our introductory Comprehensive Performance Package, so please contact us at email@example.com or phone 0344 332 0852 if you are interested in booking in with us.
How Often? – For athletes completing 5-6 days of training per week, undertaking multiple training sessions within a day, or having a generally high training volume, training low is inevitable, as it can be a challenge to consume sufficient food to meet the carbohydrate requirements of exercise. In this scenario, there is little need to program low training sessions into your week as it is likely to occur anyway. A focus on optimal fuelling is likely to be the best approach and an awareness of when your glycogen stores might be low, can help you to better manage the negatives of training low. Please note that if this situation sounds familiar to you, you should turn the sentiment of this article on its head and ensure that you schedule enough TH sessions into your program. For the average athlete with limited time to train (say 3-4 sessions a week totalling 4-5 hours of training), it is important to maximise the time you have available by creating the greatest training stress possible. The inclusion of a 1-2 hour TL session could bring about aerobic benefits similar to a much longer well-fuelled session, so is the ideal approach for time-starved endurance athletes. However, limiting it to around 1-2 sessions at most will help ensure the balance between TH and TL training.
Training Intensity – Training low will increase the perceived exertion of a training session. It’s also impossible to tap into the anaerobic (high power output) system without a good supply of carbohydrate. To prevent this influencing the quality of the session, it is important to choose sessions that are not too prolonged or intense in nature. As mentioned earlier, an all-out interval session would be almost impossible or highly compromised when in a TL state, but a 1-2 hour low intensity ride would be perfectly targeted. Drinking a strong black coffee before the session, can help you through these sessions because of the benefit that caffeine can have on performance, particularly when fatigued. Rinsing a carbohydrate drink around your mouth without swallowing it has also been shown to help to reduce the perception of effort when glycogen stores are low, but don’t expect any miracles if you’re going to try this (Kasper et al., 2016).
Immune Function – A lack of carbohydrate can put your immune system under significant stress and leave you more at risk of illness and infection. If you complete the session well hydrated and avoid any unaccustomed training sessions, you can help limit the negative impact to the immune system and reduce the chances of picking up an illness or infection.
Protein Breakdown – Consuming around 20-25grams of a lean protein source, such as 2-3 scrambled eggs before a session can help to offset the breakdown of protein during a TL session and help keep hunger at bay. TORQ’s developing SNAQ range offers some practical solutions to this problem too, by providing some specifically designed high protein/low carb breakfast and meal options to be used in conjunction with these unique periodized sessions.
Recovery Meal – Training in a low state can help stimulate the muscles to respond and adapt in a way that is going to be advantageous to your aerobic system, however, for these adaptions to occur the body doesn’t just require the training stimulus, it also requires the nutrients for these adaptions to take place. It is therefore important to follow-up the training session immediately with a high-quality carbohydrate and protein recovery drink/meal to ensure the body has the nutrients required to create these adaptions.
Recovery Time – Completing a TL session can increase the amount of time it takes to recover in comparison to a well-fuelled session, so you will need to consume a carbohydrate and protein-rich diet for 24-48 hours if you’re wanting to follow up with a useful high intensity exercise bout. Selecting a session prior to a rest day would represent the ideal option. For this reason, it may also be best to avoid this type of training around competition too. TL is a relatively new area of research and we can’t pretend to have all the answers, but we have drawn the following conclusions, which we hope will help you to make the right choices:
If you’re time-limited, periodizing 1-2 TL sessions per week into your regimen may provide aerobic benefits over a 1-2 hour period that would otherwise require a longer ‘fuelled’ session. Combine these TL efforts with 2-3 well fuelled sessions.
If you’re an accomplished athlete with a significant amount of time available for training, you could still benefit from some TL sessions if you take some time to analyse at which points during your schedule your carbohydrate stores are likely to be naturally low, despite good fuelling practices. These would tend to be at the end of a run of high load training, leading up to a rest day and we feel that this should be an ideal time to put a ‘Low’ training session into your schedule. You can then follow it with a rest day, high carbohydrate diet and get back down to business. Be aware that if you’re not currently fuelling your training properly, you’re likely to get much bigger rewards by paying attention to this than any committed TL sessions.
If you’re a complete beginner or novice athlete, get a solid few months of training under your belt before you even start to consider something like this. A focus on optimal fuelling will help you enjoy your training and likely get more out of it in the early stages of your athletic career.
To summarise, TL is a tool that can help you to get more out of your training, but don’t expect magical results from it. The downsides must be very carefully managed to ensure that this method doesn’t negatively impact your training and remember, the key is, as with many things in life, it’s all about ‘balance’. Also (and this can’t be stressed strongly enough) many people don’t fuel their training sessions properly anyway and are therefore undergoing a TL regimen without even realising it. Although this may provide associated benefits such as mitochondrial biogenesis, their performance will suffer because of inadequate fuelling for many of their sessions and lack of metabolic flexibility. These people would make huge gains through consuming more carbohydrate ahead of and during the training sessions that really depend on it as a fuel source. The vast majority of people who haven’t followed a structured fuelling regimen before and have gone on through our advice to increase their intake of carbohydrate-rich foods and use TORQ products, have made significant performance gains through increasing carbohydrate availability. Therefore, if you are going to schedule some TL sessions into your routine, it’s vital that you plan them properly and think about the bigger picture. A random approach is unlikely to get you very far and you would be much better off sticking to a high carbohydrate diet and fuelling every session properly.
Bartlett, J. D., Louhelainen, J., Iqbal, Z., Cochran, A. J., Gibala, M. J., Gregson, W., … & Morton, J. P. (2013). Reduced carbohydrate availability enhances exercise-induced p53 signalling in human skeletal muscle: implications for mitochondrial biogenesis. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 304(6), R450-R458.
Hulston, C. J., Venables, M. C., Mann, C. H., Martin, C., Philp, A., Baar, K., & Jeukendrup, A. E. (2010). Training with low muscle glycogen enhances fat metabolism in well-trained cyclists. Medicine and Science in Sports and Exercise, 42(11), 2046-2055.
Kasper, A. M., Cocking, S., Cockayne, M., Barnard, M., Tench, J., Parker, L., … & Morton, J. P. (2016). Carbohydrate mouth rinse and caffeine improves high-intensity interval running capacity when carbohydrate restricted. European journal of sport science, 16(5), 560-568.
Lane, S. C., Camera, D. M., Lassiter, D. G., Areta, J. L., Bird, S. R., Yeo, W. K., Jeacocke, N.A., Zierath, J.R., Burke, L.M., & Hawley, J. A. (2015). Effects of sleeping with reduced carbohydrate availability on acute training responses. Journal of Applied Physiology, 119(6), 643-655.
Marquet, L. A., Brisswalter, J., Louis, J., Tiollier, E., Burke, L. M., Hawley, J. A., & Hausswirth, C. (2016). Enhanced endurance performance by periodization of CHO intake:“sleep low” strategy. Med Sci Sports Exerc. doi, 10.
Marquet, L. A., Hausswirth, C., Molle, O., Hawley, J. A., Burke, L. M., Tiollier, E., & Brisswalter, J. (2016). Periodization of Carbohydrate Intake: Short-Term Effect on Performance. Nutrients, 8(12), 755.
Morton, J. P., Croft, L., Bartlett, J. D., MacLaren, D. P., Reilly, T., Evans, L., … & Drust, B. (2009). Reduced carbohydrate availability does not modulate training-induced heat shock protein adaptations but does upregulate oxidative enzyme activity in human skeletal muscle. Journal of Applied Physiology, 106(5), 1513-1521.
Stellingwerff, T., & Cox, G. R. (2014). Systematic review: Carbohydrate supplementation on exercise performance or capacity of varying durations 1. Applied Physiology, Nutrition, and Metabolism, 39(9), 998-1011.
Van Proeyen, K., Szlufcik, K., Nielens, H., Ramaekers, M., & Hespel, P. (2011). Beneficial metabolic adaptations due to endurance exercise training in the fasted state. Journal of Applied Physiology, 110(1), 236-245.
Yeo, W. K., Paton, C. D., Garnham, A. P., Burke, L. M., Carey, A. L., & Hawley, J. A. (2008). Skeletal muscle adaptation and performance responses to once a day versus twice every second day endurance training regimens. Journal of Applied Physiology, 105(5), 1462-1470.
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