I generally write about strength training for the endurance athlete but for once I will get out the gym and move into the kitchen. Performance is not just a matter of training, what and when we eat is key to optimize training adaptations and reaching our full potential.
This post will dispel two myths, (1) You should always ensure you consume carbohydrates before, during and after training sessions. (2) You should never train on an empty stomach.
It is well established that carbohydrate availability improves exercise capacity in endurance athletes. I am not re-inventing the wheel here, most of you know this already.
But I am sure that my next question is going to make you think a bit more: Should we always ensure maximal carbohydrate availability before, during and after training sessions in order to promote maximal training adaptations? In other words, is glycogen beneficial during training?
The answer is NO, so you can start saving money on sugary drinks and energy gels.
Nearly one decade ago, a pioneer study sought to answer the very same question. The study found that carbohydrate depletion during training was beneficial to performance. http://jap.physiology.org/content/jap/98/1/93.full.pdf
The watershed investigation of Hansen and colleagues challenged many years of study in this topic, since it provided apparent evidence to support training in a glycogen depleted state. The study required the participants to train one leg with a ‘‘two a day’’ training protocol every second day, while the contra lateral leg undertook the same workouts, spread over a daily training schedule. Maximal power output increased equally in each leg, but the leg that trained twice-a-day, commencing 50% of its training sessions with a low glycogen concentration, showed greater increases in kicking endurance accompanied by greater maximal activity of an ‘‘aerobic’’ enzyme.
Both limbs performed identical work (loads, sets and repetitions) but the limb that completed 50% of training with reduced muscle glycogen, showed superior training adaptations.
This breakthrough result led many researches to study the effects of restricted carbohydrate availability in different settings.
Yeo et al (2008) conducted a research with two groups of elite endurance cyclist. The first group trained daily and the second group trained twice every second day during three weeks. The outcome showed again an enhanced training adaptation profile after twice every second day “low-glycogen” training, more importantly cyclist who trained with reduced muscle glycogen were able to increase their ability to utilise fat as an energy source, sparing muscle glycogen which will be much needed in the later stages of an endurance event. http://jap.physiology.org/content/jap/105/5/1462.full.pdf
It is worth mentioning that another research showed once again that training in a glycogen depleted state resulted in improved training adaptations, this time in runners. Three groups took part. Group 1- One training session a day. Group 2-Two training sessions every other day, consuming a placebo drink before and during every second training session Group 3- Two training sessions every other day, consuming a sports drink before and during every second training session. The results showed that training with reduced pre exercise muscle glycogen levels and without the provision of energy drinks (group 2) provides an enhanced stimulus for inducing fat usage, consequently sparing muscle glycogen. It is also remarkable, that the consumption of a sport drink off-set the training adaptations in group 3.
All the studies mentioned above required training twice a day in order to exhaust glycogen stores in the muscle and enhance training adaptations, but realistically most people are unable to schedule two training sessions in the same day.
Perhaps, a more simpler way to restrict carbohydrates is actually to adapt your carb consumption to your training. Thus, training in a fasted state in order to deplete the glycogen stores and enhances training adaptations. (Yes, there is research supporting this dietary periodization and you can find it here.) http://jap.physiology.org/content/jap/110/1/236.full.pdf
Training in the morning before having breakfast is the most practical way to get a session in a glycogen depleted state but there are a few risks associated with this approach if it is not implemented correctly:
1-Reduced training intensity. Liver glycogen is low after sleeping, which leads to reduce blood glucose, making exercise seem more difficult.
2-Impaired immune function.
3-Protein degradation & loss of muscle mass
Do not get frightened, there are some tips you can follow to avoid all the possible negative effects of fasted running:
1-You don’t have to do all your runs in a fasted state, select those sessions in which absolute training intensity or duration is not a major goal. ‘Easy / recovery runs’ are ideal to take action and try fasted running.
2- Hydration is essential, water or a low-calorie electrolyte drink should be consumed.
3- Eating is possibly the most rooted habit we have. Altering that habit by skipping a meal can be extremely challenging for some people. If you can’t handle exercise without food in your stomach, you can consume a protein-only breakfast accompanied with caffeine (100-150mg), to help prevent protein breakdown and reduce the risk of fasted training. For example, two scrambled eggs and a cup of strong coffee.
4-Increase protein contain in your diet, I will write a post on this topic in the next few weeks, keep reading my blog.
Hansen, Anne K., Christian P. Fischer, Peter Plomgaard, Jesper Løvind Andersen, Bengt Saltin, and Bente Klarlund Pedersen. Skeletal muscle adaptation: training twice every second day vs. training once daily. J Appl Physiol 98: 93–99, 2005
Yeo, W. K., Paton, C. D., Garnham, A. P., Burke, L., 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 (Bethesda, Md.: 1985), 105, 1462–1470
Morton JP, Croft L, Bartlett JD, MacLaren DP, Reilly T, Evans L, McArdle A, Drust B. Reduced carbohydrate availability does not modulate training-induced heat shock protein adaptations but does upregulate oxidative enzyme activity in human skeletal J Appl Physiol 106: 1513–1521, 2009.
Van Proeyen K, Szlufcik K, Nielens H, Ramaekers M, Hespel P. Beneficial metabolic adaptations due to endurance exercise training in the fasted state. J Appl Physiol 110: 236–245, 2011