Low Glycogen Training for the Endurance Athlete

Train Low

If social media is anything to go by, it often seems like there are two opposing schools of thought in sports nutrition at the moment. In one camp are those who believe that ‘carbohydrate is king’, basing their daily diet around regular intake of starchy carbohydrates like pasta, bread, crackers, rice, potato, oats and other grains, supplemented with plenty of fruit (and hopefully vegetables too) and perhaps some carefully chosen sources of sugar like dried fruit, honey and maple syrup. In addition, they might regularly fuel their workouts with energy bars, sports drinks and gels, not to speak of carefully consuming a carbohydrate and protein drink after training to aid their recovery. There is certainly plenty of research to back up that traditional approach to endurance sports nutrition and plenty of athletes out there, recreational and professional, who vouch for its effectiveness in terms of performance and recovery.

In the other camp, are those athletes who swear by the ‘new’ LCHF approach of a low carbohydrate high fat diet, where the carbohydrates are kept to a minimum – perhaps 50-100g of vegetables each day and no grains or fruit – and the bulk of calories in the diet come from fats like olive oil, coconut oil, fatty meats and fish, avocado, nuts and seeds and full fat dairy products. Proponents of this way of eating – which currently has few scientific research studies available to back it up, but an increasing anecdotal evidence base, particularly among athletes tackling longer distance events – point to an increased fat burning capacity at moderate exercise intensities, reduced need for calories during training and racing and improved endurance performance. They minimise their use of sports nutrition products and sugar, preferring a ‘real food’ approach during training and racing, and can often perform for 2-3 hours without taking on any nutrition at all.

As ever with nutrition, everyone is different in the way their body responds to food and many people may well thrive on one of the ways of eating that I’ve outlined above. But a solid research base 1, 2 is building for an approach that in a way takes the best of these two worlds and uses a nutrition strategy that is periodized through the year, and even within an individual training week at certain times a year, so that there are days when you deliberately train with low glycogen (ie carbohydrate) stores and others when you undertake training with at full glycogen capacity, topping up as required during the session. You then always race in a high carbohydrate state. This approach, which does not involve following a high fat diet but reduces the proportion of carbohydrates in the diet at times, is sometimes known as ‘train low race high’ and it is one that I now recommend to endurance clients who have traditionally thrived on high carbohydrate diets but are looking for a step up in performance or are concerned about their body composition.

The idea behind ‘train low race high’ is that when you train with low muscle glycogen by refraining from consuming carbohydrate, certain adaptations take place in muscle cells, notably an increase in the number of mitochondria that burn fuel to produce energy, a process which is known as mitochondrial biogenesis. Studies have shown that over time, this may produce increased endurance capacity and performance.3 Training ‘low’ also improves your body’s fat burning capacity as your mitochondria are forced to use body fat as fuel instead of carbohydrate. This may have benefits for body composition and also – over time – increase the intensity at which you can exercise using predominantly fat as fuel, preserving glycogen stores which means that you need to take on less sugar during your long training sessions and races. This may have benefits if you are prone to gastro-intestinal issues when you consume a high amount of sports nutrition product.

But if you follow the ‘train low’ approach, you do have to carefully plan when you are going to do this. The idea is not to do all your training low carb and then load up with carbs just prior to race day, or to follow a low carb diet day in, day out. There are two reasons for this: first, doing high intensity training sessions is hard in a low glycogen state and this may adversely affect the benefits you are looking for from this type of training if you can’t complete it properly due to a lack of fuel. Essentially there is a point of intensity beyond which your body is completely dependent on carbohydrate to convert into energy. This varies by person and their individual fat burning capacity. Regardless, if you train for and compete in events that last three hours or less, you are going to need fully stocked carbohydrate stores to hold your race pace or above.4 The second reason is that research has shown that you lose your ability to convert carbohydrate to energy efficiently if you don’t train ‘high carb’ at times.4 You may find it difficult to reach a faster pace or to hold a period of higher intensity, which may be required at times during races of longer than three hours, as well as for much of the duration of shorter races.

So when is it best to ‘train low’? Probably do most of your training of this type in the Base period of your training year. But don’t do every workout on low glycogen stores; perhaps 2-3 sessions a week, generally the lowest intensity ones. In the Build period, reduce your low glycogen training to occasionally only, such as a recovery run or ride or an easy swim. Most of your workouts should now be supported with carbohydrate consumption prior to training and use of sports nutrition products, eg 30-60g of carbohydrate an hour, if they last over 90 minutes. This periodized approach will help you to develop ‘metabolic flexibility’ which is the ability to use different fuel sources, eg fat and carbohydrate, at the appropriate times. As a possible alternative, there’s also been research published recently 5 which indicates that you can follow a ‘train low’ approach throughout a two week period and see performance benefits, without the risks of a long period of low carbohydrate intake.

How do you train low? Try these different ways:

  • Train before breakfast on an empty stomach, ie fasted.
  • Do your first workout of the day after consuming some carbohydrate and then do not eat any carbs afterwards. Perform your second daily session on low carb stores.
  • Train for more than 90 minutes without taking on any carbohydrate during the session.
  • Don’t have any carbohydrate for 2-4 hours after training instead of your usual recovery meal.
  • Train after an evening meal, then again the next morning without consuming any carbohydrate until after the second workout.

As a possible alternative, there’s also been research published recently which indicates that you can follow a ‘train low’ approach throughout a two week period and see performance benefits, without the risks of a long period of low carbohydrate intake. 5

Training low does carry some potential downsides, particularly in terms of an increased risk of overtraining and suppressing the immune system. To help prevent this, it’s a good idea to have some protein such as eggs or a protein drink before a long low carb session 6, to have a cup of coffee before fasted workouts and to consider using a sports drink as a mouthwash during your workout.1 Both the latter strategies have an effect on the nervous system which appears to reduce the stress of training. It’s also important to stay hydrated with water and to add electrolyte tablets on long workouts or if you have a high sweat rate.

If you would like to read more about the studies which have influenced the ‘train low race high’ approach, I recommend this 2015 review paper 7 by Professor Louise Burke from the Australian Institute of Sport. It also gives a balanced view on the high carb vs high fat controversy and explores the concept of metabolic flexibility.

I hope the periodized ‘train low race high’ nutritional approach works well for you if you decide to give it a try.

Jo Scott-Dalgleish BSc (Hons), mBANT, CNHC, is a registered nutritional therapist specialising in nutrition for endurance sport, based in London. She works with triathletes, distance runners and cyclists to help optimise both their performance and their health through the creation of an individual nutritional plan.

For more details, please visit www.endurancesportsnutritionist.co.uk.


1 Bartlett JD, Hawley JA and Morton JP. Carbohydrate availability and exercise training adaptation: too much of a good thing? Eur J Sport Sci. 2015; 15(1): 3-12 http://www.ncbi.nlm.nih.gov/pubmed/24942068

2 Marquet et al. Enhanced endurance performance by periodisation of CHO intake: “Sleep Low” strategy. Med Sci Sports Exerc. 2016. Jan 7 [Epub ahead of print]. http://www.ncbi.nlm.nih.gov/pubmed/26741119

3 Craig et al. Utilising small nutrient compounds as enhancers of exercise-induced mitochondrial biogenesis. Front. Physiol. 27 Oct 2015. http://www.ncbi.nlm.nih.gov/pubmed/26578969

4 Hawley JD and Leckey JJ. Carbohydrate dependence during prolonged intense endurance exercise. Sports Med. 2015; 45(Suppl 1): 5–12. http://www.ncbi.nlm.nih.gov/pubmed/26553495

5 Cochran et al. Manipulating carbohydrate availability between twice daily sessions of high intensity interval training over two weeks improves time trial performance. Int J Sport Nutr Exerc Metab. 2015 Oct; 25(5): 463-70 http://www.ncbi.nlm.nih.gov/pubmed/25811132

6 Taylor et al. Protein ingestion does not impair exercise-induced AMPK signalling when in a glycogen depleted state: implications for train-low compete high. Eur J Appl Physiol. 2013; Jun: 113(6): 1457-68 http://www.ncbi.nlm.nih.gov/pubmed/23263742

7 Burke LM. Re-Examining High-Fat Diets for Sports Performance: Did We Call the ‘Nail in the Coffin’ Too Soon? Sports Med. 2015 Nov;45 Suppl 1:33-49 http://www.ncbi.nlm.nih.gov/pubmed/26553488

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Author: Jo
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