One of the hottest areas of research in endurance exercise sports concerns the effect of reduced carbohydrate availability on modulation of training-induced adaptations in skeletal muscle. Popularly termed ‘train-low, compete-high’- this new paradigm of endurance training involves commencing selected training sessions where carbohydrate availability is deliberately reduced. However, when it comes to competing, carbohydrate availability should always be high so as to maximise performance. A scientific review on this emerging and popular approach to endurance training has just been published in the European Journal of Sport Science, essentially proposing that ’cycling’ carbohydrate availability for select training sessions or training blocks may in fact be the best way to promote optimal endurance training adaptations.
There are said to be many potential benefits of commencing endurance-based exercise sessions with reduced carbohydrate availability, such as enhanced activation of cell signalling pathways involved in energy metabolism, up-regulation of oxidative enzymes, increases in whole-body and intramuscular fat oxidation and in some instances, improves exercise capacity1. However, the most important adaptations that occurs as part of the train-low compete-high approach is the increase in mitochondrial mass (which in scientific goobledegup is called mitochondrial biogenesis)1. This ultimately allows individuals to exercise at higher absolute intensities for a longer duration; the basic goal of every endurance athlete. The mechanisms that mediate these changes at the cellular level are very complex and beyond the scope of this article. Nonetheless, a lot of the theory and practical application of the train-low compete-high approach has been covered in an earlier article. The latest joint publication on the train-low compete-high approach is by researchers from the Australian Catholic University and the Liverpool John Moores University in UK. It provides some good practical nutritional guidelines that can minimise some of the drawbacks of training low as well as decrease some of the risks. These points are summarised below.
Train Low Whenever Intensity and/or Duration Permits
The best times to incorporate a train low session is when a given athlete is already scheduled to have a session that is long and/or of a lower intensity. Because depleted glycogen stores invariably limit power and energy availability, it’s very hard to punch out any sort of decent power or pound the pavement with any fury. Therefore, planned long slow recovery session provide the ideal opportunity to implement a low carb session, as such sessions by their nature don’t require high power outputs.
Caffeine & Carbohydrate Mouth Rinse
One of the biggest obstacles when using a train low approach is that exercise intensity is invariably diminished. Fortunately, there are some nutritional strategies that can help reduce the perceived increase in effort associated with training low. Caffeine supplementation is possibly one of the most effective strategies for reducing perceived effort, plus it doesn’t have any negative effect on the favourable molecular adaptations that occur at the cellular level.
One area where there is a large degree of individual variance in response to train low regimes is with respect to immunity. Temporary immune suppression is a known risk with intense training and carbohydrate supplementation during/before exercise is an effective strategy to offset this suppression. Therefore, removing carbohydrate intake either during or after exercise can predispose certain individuals to increased risk of infection resulting from intense and/or prolonged training. A recent study has provided some exciting news in that protein supplementation can effectively offset the temporary immune suppression associated with training low. The only catch is that you have to go pretty heavy with the supplementation, namely, 20-25g before, during and/or after exercise. This has the combined effect of reducing protein breakdown associated with exercise as well as decreasing the immune suppression associated with training low.
Don’t Exclude High Carb Intake Completely
While training with low glycogen availability has many benefits for favourable endurance training adaptations, researchers in this area recommend that athletes regularly schedule days/sessions with high carbohydrate intake. This is in order that the body does not become unaccustomed to using carbohydrate effectively as a premium fuel source during high intensity exercise. Moreover, replete glycogen stores are required for optimal performance and its important athletes regularly incorporate sessions with high intensity and high carbohydrate stores.
Bartlett JD, et al. Carbohydrate availability and exercise training adaptation: Too much of a good thing? Eur J Sport Sci. 2014 Jun 19:1-10. [Epub ahead of print]