Train Low, Compete High to Optimise Training

Train Low, Compete High to Optimise Training

You’ll know the term «Train Low, Compete High», right? It’s something like training in reserve to make more use of the gasoline in competition.

What is “train low, compete high” exactly?

“Train low, compete high” refers to the protocol of nutritional manipulation where an endurance athlete (it doesn’t make sense in other sports)trains with a low availability of glucose and their body reserves (glycogen) to improve their performance on the day of competition training under normal conditions.

This is after filling their concentrations to levels that we know will help us perform better (Hall, 2016).

The train low, compete high protocol is a hot topic. That’s to say, something being talked about intensely at the moment, mostly because of its ability to create an opportunity to improve bioenergetic efficiency (known as metabolic flexibility, meaning, the capacity to change energy source depending on needs) and improve training.

If you want to find out more about Metabolic Flexibility, try this link.


What’s the purpose of ‘train low, compete high’?

Since the 50s, Astrand have been experimenting with the idea of muscle glycogen manipulation to increase sports performance, and the principle has been created many offshoots.

We know that during high-intensity exercise glucose is the body’s principle substrate, as the body requires less oxygen to oxidise this nutrient than fats, as glucose is more oxygen dense.(Boron and Boulpaep, 2017).

Fatty acids are a less efficient nutrient than glucose for use as an energy source during high-intensity exercise.

Astrand and researchers in the field made a simple association:

“If glucose is the main limitation of intensity, the glucose in the body is stored as glycogen, and this is reduced during physical exercise; if the concentrations of glycogen increases, then there’s more glucose to use and endurance will be better.

A brilliant association at a time when the biomolecular mechanisms modulating catabolism were not so clear.

The protocols used are simple:

  1. Reduce the intake of carbohydrates a few days before the competition, together with very high effort training to “empty” our glycogen stores.
  2. This should be followed by a few days (usually 2-3) of a high carbohydrate diet in order to conserve more glycogen than we had before as a “backup mechanism, just in case”

Classic protocol

Figure I. Example of a classic glycogen depletion/supercompensation protocol (Laurent et al., 2000).

The results are very effective, and function brilliantly for increasing glycogen concentrations.

Does it work?

The train low, compete high protocol is a hugely popular concept, and many people get it confused.

So, I’ll make it clear:

The advantages of the train low, compete high protocol are NOT due to the overcompensation of glycogen concentrations.

For that, we have other simpler protocols; the train low, compete high goes further. As you’ll see…

How ‘train low, compete high’ works

At the biomolecular level

Most studies that associate the train low protocol, compete high with improvements in metabolic flexibility are based on the biomolecular models that have been proposed after animal studies with the protocol.

They are summarised in this image:

Biomolecular mechanisms

Figure II. Graphic sumary of the biomolecular mechanisms that mediate the adaptations of ‘train low’ (Impey et al., 2018).

The mechanisms through which this protocol can improve the ability to prolong effort and improve nutrient utilisation are incredible:

The decreased availability of glucose in the body increases the signalling of catecholamines (adrenaline) by hydrolysing intramuscular triglycerides and using their free fatty acids as energy; joined of course, to the fatty acids released from the adipocytes, which antagonise mTORc1 and activate AMPK.

These mechanisms activate a number of proteins and transcription factors (PPARδ, PGC-1α, NRF-1/-2 and proteins such as p53 and p28) that activate genes within the nuclei of muscle cells that promote mitochondrial biogenesis;

This, together with a low availability of glycogen that activates AMPK by increasing the AMP:ATP ratio, generates a series of molecules that have the capacity to signal not only the increase in density, but also the activity of the mitochondria, making it possible that:

We have more places in the body to oxidise nutrients for energy, and are also more efficient in the process.

More workers and better coal-burning machinery.

This protocol really promises to be a before and after in nutritional planning and nutrient-gene interaction in in vitro models; but there is a problem…

A proposed (biomolecular) model does not always have a significant effect on an in vivo model.

At the functional level

Yes, there is a marked effect on molecular signalling (73% of studies with positive results), gene expression (75% of studies with positive results), and the activity and density of catabolic enzymes (78% of studies with positive results) in human models.

However, when we evaluate the real changes in performance, we see that only 37% of the studies show that the train low, compete high protocol is superior to following a standard nutritional periodisation.

In addition, a majority of the studies that observe this nourish the control group with low carbohydrate diets (2-5g/kg), meaning they are not being evaluated on an equal footing.

If you were to feed the “comparison” group with 8-12g/kg, the percentage of studies showing positive results would be much lower.

Glycogen threshold paradigm

The currently proposed model, through which the “in vivo” train low, compete high protocol works, is the glycogen threshold paradigm model.

This protocol establishes that concentrations between 100mmol and 300mmol/kg of glycogen in dry matter allow us to maintain acceptable performance and still benefit from the molecular effects of “train low”.

Glycogen concentrations

Figure III. Variations in endogenous glycogen concentrations in studies with different physical exercise protocols. The grey area represents the glycogen threshold (Impey et al., 2018).

But as we can see, many training protocols reach these thresholds without “train low”.

Physical exercise itself is able to get you in there, even if you start from a high availability of glycogen before you start training.

Do I recommend it?

I wouldn’t say the train low compete high is bad per say… but that we have to put what we know into perspective with what we are presented with:

We know that glucogenic is a condition of the capacity to maintain physical effort in time, which is also important for being, amongst many other processes:

  • An effort perception regulator;
  • A regulator of the balance between protein synthesis and degradation
  • A metabolic barometer controlling energy expenditure at rest and regulating muscle contraction…

Trail running

Are you really interested in conditioning all this?

We know that concentrations of dry tissue lower than 75mmol glycogen/kg alter the sarcoplasmic reticulum’s ability to handle calcium, causing our maximum muscle contraction to decrease.

The utility threshold of the train low is around 200mmol/kg, a cut-off point that we know adversely affects performance.

And how are you going to control it?

Are you going to be doing muscle biopsies on the vast exterior before and after your workouts?

We don’t yet know a less invasive method (well, we do know, but it’s not realistic) to measure glycogen concentrations in the body .

Are you going to apply the protocol blindly?

Of course! Like many other systems, logically, if carried out under the control and monitoring of a multidisciplinary team of health professionals; if not, no.

So, personally, if you’re not a high performance athlete with a team behind you, I would never do a train low, compete high protocol, not as people understand it, which is to reduce carbohydrate intake drastically and increase it for competition.

How then do I use the protocol?

If you decide to apply this system of nutritional periodisation try not to extend it to all your training sessions. That would be a mistake…

Why would you want to train low in a set session above the VT2 where you know you’re going to accumulate a lot of fatigue and need glycogen to perform?

Limit the “low” system to low intensity sessions, where our RER (RQ) is lower and we don’t need so much oxygen and therefore use more fat in training.

Energy density

Figure IV. Energy density and respiratory quotient associated with the predominant oxidation of different nutrients (Boron and Boulpaep, 2017).

You can apply the protocol through different systems, but each of them must be programmed in a different way, since it has particular characteristics that are relevant for different times of the season.

Main protocols and effects on the body

Diet-Exercise StrategyKey ResultsProposed Application
Chronic exposure to a low-carbohydrate dietReduction in the availability of carbohydrates at the muscular level during all training sessions, depending on the degree of restriction applied.Perhaps in extremely lightweight training blocks. It’s not a recommended protocol.
Low availability of general carbohydrates: effects on the body, including the immune system and the central nervous system
Double training sessions (low endogenous availability of carbohydrates in the second session of the day limiting the duration and intake of carbohydrates in the recovery period after the first session)Reduced availability of endogenous and exogenous carbohydrates to the muscle during the second training sessionIn training blocks where high rates of effort are not reached systematically in the training sessions, assuming that the second session is always performed at VT1 or below.
Acute reduction in carbohydrate availability to the immune system and central nervous system, depending on the duration of the carbohydrate restriction and the requirements of the second session
Training after the night fastReduction in exogenous carbohydrate availability to the muscle in a specific session.“Recovery” or “fitness” training days.
Potential reduction in the availability of endogenous carbohydrates if there is inadequate restoration of glycogen the day before
Prolonged training with or without overnight fasting and/or restriction of carbohydrate intake during the sessionReduction of exogenous carbohydrate sources to the muscle during the specific sessionNever, except for specific ultra-distance scenarios (marathon, ironman…).
Acute reduction in carbohydrate availability to the immune system and central nervous system, depending on the duration of the carbohydrate restriction and the energy requirements of the session.
Carbohydrate restriction during the first hours of recoveryIt could provide sufficient energy availability during the session, but restrict it for post-exercise signalling activities.On days when there are no double sessions and therefore no need to replenish the glycogen lost in the short term.

Figure V. Train low application strategies and main organic manifestations; adapted from Burke, 2010. Own source applications.

Nutritional periodisation

A possible nutritional periodisation following this protocol could be the one proposed by Impey et al., (2018):

Proposed schedule

Figure VI. Proposed schedule for the application of a train low system in a micro training cycle of a runner training 4 days a week with a mixed protocol (Impey et al., 2018).

Adapt the protocol individually

This scheme must be adapted to the training protocol of each person, but it serves as a mental image of how to sequence the availability of glycogen in a micro cycle of 4 sessions with different training loads per session.

The authors themselves say to establish “low/medium/high” and not quantities, because these must be adapted to the:
  • Sporting background;
  • Biological characteristics;
  • Large number of factors unique to the athlete.

Unknowns and limitations

There are currently 4 major unknowns regarding the train low protocol, compete high that, until they are resolved, mean we can’t progress in finding out its full usefulness and real applicability in an athlete:

  • Glycogen threshold

    • Is there really a threshold (range) of glycogen where protocol-mediated adaptations occur?
    • How is this threshold affected by training (because we know that an athlete does not accumulate the same amount of glycogen as a sedentary person, so the range should be shifted).
  • Use in low or high intensity sessions

    • Should the “train low” always be for low intensity sessions, or could it be deliberately applied to high intensity sessions (even at the expense of reducing the absolute workload) so that the session’s metabolic signalling can actually be optimised?
  • Carbohydrate quantities

    • What is the minimum amount of carbohydrates we can ingest and the glycogen concentrations required to facilitate “train low” periods without compromising the overall intensity of training during specific sessions?
  • Calories or carbohydrates?

    • Is the increase in training response associated with a “train low” in carbohydrates or energy (calories)? And in any case, how should we periodise and structure training interventions to avoid misadaptations?
Are all these new molecular targets really relevant enough to regulate nutrient intake and exercise planning?

As you can see, there are many unresolved questions, and therefore, the ‘train low, compete high’ protocol is a still «taking its first steps».

The stomach and intestines of athletes train too

And let’s not forget, reducing widely and deliberately the consumption of carbohydrates can also diminish the capacity to digest and absorb them correctly; a trained athlete can replenish 5-6mmol/kg of dry matter/hour, at best…

When we stop consuming carbohydrates, when they are reintroduced in large quantities, our gastric emptying will be slow, we’ll feel bloated, we’ll absorb less glucose per unit of time, and in the end our performance will be worse off.


Figure VII. Proposed model of intestine training methods, their physiological effects and behavioural benefits (Jeukendrup, 2017).


The train low, compete high protocol is a nutritional periodisation system that is very on trend.

At a biomolecular level, it has great potential, however, at a functional level, its effects are overtaken by good training and nutritional planning.

Most of the practitioners of the train low, compete high system use strategies that harm them more than help them, because they don’t know the real ins and outs of the protocol.


We need specific measurement tools in order to apply the protocol correctly.

There are still unknowns about the mechanisms underlying the physiological responses produced by the protocol.

Personally, as an endurance athlete trainer, I have not used and would not use the train low protocol, except at times in pre-season when the training load is low and therefore the energy needs are also low, or in scenarios of extreme fatigue conditions in ultra-distance runners.

Bibliographic Sources

  1. Boron, W., Boulpaep, E. (Eds.) (2017). Medical physiology: a cellular and molecular approach Philadelphia, PA: Saunders/Elsevier.
  2. Burke, L. M. (2007). New issues in training and nutrition: Train low, compete high? Current Sports Medicine Reports, 6(3), 137–138.
  3. Burke, L. M. (2010). Fueling strategies to optimize performance: Training high or training low? Scandinavian Journal of Medicine and Science in Sports, 20(SUPPL. 2), 48–58.
  4. Hawley, J. A., & Burke, L. M. (2010). Carbohydrate availability and training adaptation: Effects on cell metabolism. Exercise and Sport Sciences Reviews, 38(4), 152–160.
  5. Impey, S. G., Hearris, M. A., Hammond, K. M., Bartlett, J. D., Louis, J., Close, G. L., & Morton, J. P. (2018). Fuel for the Work Required: A Theoretical Framework for Carbohydrate Periodization and the Glycogen Threshold Hypothesis. Sports Medicine, 48(5), 1031–1048.
  6. Jeukendrup, A. E. (2017). Periodized Nutrition for Athletes. Sports Medicine, 47(Suppl 1), 51–63.
  7. Jeukendrup, A. E. (2017). Training the Gut for Athletes. Sports Medicine, 47(Suppl 1), 101–110.
  8. Laurent, D., Schneider, K. E., Prusaczyk, W. K., Franklin, C., Vogel, S. M., Krssak, M., … Shulman, G. I. (2000). Effects of Caffeine on Muscle Glycogen Utilization and the Neuroendocrine Axis during Exercise 1 . The Journal of Clinical Endocrinology & Metabolism, 85(6), 2170–2175.
  9. Mata, F., Valenzuela, P. L., Gimenez, J., Tur, C., Ferreria, D., Domínguez, R., … Sanz, J. M. M. (2019). Carbohydrate availability and physical performance: physiological overview and practical recommendations. Nutrients, 11(5).
  10. Morton, J. P., Croft, L., Bartlett, J. D., MacLaren, D. P. M., 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.
  11. Murray, B., & Rosenbloom, C. (2018). Fundamentals of glycogen metabolism for coaches and athletes. Nutrition Reviews, 76(4), 243–259.

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About Alfredo Valdés
Alfredo Valdés
A specialist in Pathophysiology and biomolecular effects on nutrition and sportive activity who will show you the elaborate world of sports nutrition in his articles, employing a simple and critical writing.
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