Periodization of carbohydrates

Carbohydrate periodization has gained importance in recent years because it improves athletic performance . Therefore, in this guide we will explain what carbohydrate periodization is and how to implement it safely to improve your athletic performance or performance in a competition.

The first thing we need to know is that there is a close relationship between carbohydrate (CH) metabolism and athletic performance . We feel tired or fatigued when our glycogen stores begin to deplete. Therefore, when exercising, such as during a race, it is advisable to consume carbohydrates.

Carbohydrate periodization involves strategically reducing carbohydrate intake during low-intensity workouts. This is then combined with a high carbohydrate intake during specific high-intensity training or competition, allowing for a dramatic improvement and adaptation in performance.

Thus, carbohydrate periodization is based on a simple yet powerful concept: not all days are the same in terms of energy requirements . For example, on days of intense training, such as high-intensity interval sessions, your body needs an adequate supply of carbohydrates to boost performance and recovery. In contrast, on rest days or days of light physical activity, carbohydrate intake can be reduced to promote fat burning. Therein lies the success of carbohydrate periodization.

How does glycogen work in our body?

Muscle glycogen can mediate cell signaling pathways associated with adaptation to resistance training (1), inducing an increased muscle transcriptional response when exercise is completed under conditions of reduced muscle glycogen availability (5, 6).

In fact, compared to loaded glycogen stores, training with reduced muscle glycogen has been shown to increase AMP-activated protein kinase (AMPK) activity as a result of decreased AMPK-glycogen binding (7, 8).

Therefore, AMPK acts as a cellular energy sensor, upregulating the activity and expression of peroxisome proliferator-activated receptor 1 coactivator alpha (PGC-1α) (9 , 10 , 11) , a transcriptional coactivator often touted as the main regulator of mitochondrial biogenesis (12 , 13), a key hallmark of adaptation to resistance training (14 , 15) .

Concomitant with these adaptations, the increased mobilization of body fat for energy supply during exercise with low glycogen availability upregulates the peroxisome proliferator-activated receptor (PPARδ) transcription factor (16) , thereby increasing the expression of proteins involved in lipid metabolism. Such metabolic adaptation can be beneficial for improving performance during prolonged submaximal steady-state exercise by sparing glycogen stores for later use (17 , 18) .

Consequently, during the last decade, various exercise-dietary carbohydrate (CHO) periodization strategies (i.e., twice-daily training, fasted training, withholding CHO intake between exercise sessions) to train with low muscle glycogen levels (coined as “low training”), have been tested in athletes (19 , 20 , 21 , 22)

What is periodized nutrition?

It is important to define the terms 'periodized nutrition' and 'nutritional training'. The words 'training' and 'periodized', by definition, refer to a structured and planned process. In reality, there is often little planning when it comes to nutrition and limited integration of training and nutritional practices. What athletes consume after exercise may depend on training, but careful planning before training, with long-term goals in mind, is still relatively uncommon. (1)

"Nutrition should be periodized and adapted to support changing individual goals, training levels, and requirements throughout a season and/or training cycle."

For example, the guide "How to Train Your Gut?" would be included in this definition of periodized nutrition

The terms periodized nutrition and nutritional training can be used interchangeably, and the selection of nutritional training methods is highly specific to the objectives (2) . For example, if the objective is to specifically develop fat metabolism, "sleep low train low" training may play a role in achieving these specific adaptations. However, to achieve adaptations in gastrointestinal (GI) absorption capacity for carbohydrates, a higher carbohydrate intake would be recommended.

There are several models like these (1) :

What is sleep low train low?

"Sleep Low-Train Low" is a training and nutrition strategy designed to deliberately reduce the availability of muscle glycogen during specific exercise sessions, potentially amplifying the training stimulus through increased cell signaling.

It includes three different training and nutrition interventions: high-intensity training (HIT) at night to deplete glycogen stores, followed by low CHO availability overnight (i.e., sleeping with few carbohydrates) and low-intensity training (LIT) the following morning under conditions of low muscle glycogen/CHO availability.

If you'd like an example and want to try it out, we've created a PDF with a training protocol (6 x 5 min cycling at 105% FTP interspersed with 5-min recovery at 55% FTP. Eight sets of 5 min high-intensity training with 60 s recovery (23) have been shown to be effective in significantly reducing muscle glycogen content (~50%) and were previously used in a "sleep low, train low" intervention (24) ) and a nutrition plan that you can follow for 3 weeks, which is when this type of strategy has been shown to be beneficial. Click here to download it.

Benefits of carbohydrate periodization

Regarding performance outcomes, improvements of 4.0%, 2.3%, and 5.5% were observed in 20 min, 5 min, and FTP (W·kg⁻¹), respectively. Using a similar exercise and nutrition intervention, Marquet et al. (3) reported an improvement in 10 km running time (-2.9%) and an increase in time to exhaustion in supramaximal cycling (150% of maximum aerobic power) (+12.5%) in triathletes, showing improvements during both aerobic and anaerobic exercise.

Understanding the daily impact of training with reduced CHO availability is important for coaches, sports scientists, and nutritionists alike.

This study demonstrates what was mentioned above.

The sleep low, train low method is one of many existing strategies for nutritional periodization. This particular one is supported by scientific evidence that advocates its use during times of the season when we want to emphasize fat oxidation.

Despite reductions in relative training intensity over three weeks, we provide data demonstrating that three weeks of “sleep low, train low” is effective in improving functional threshold power (FTP) and 5-minute PPO in trained cyclists and triathletes, with no benefit to high-intensity training. Exercise performance (1-minute PPO) compared to “normal” carbohydrate availability (4)

Literature

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4. Samuel Bennett, Eve Tiollier, Franck Brocherie, Daniel J. Owens, James P. Morton, Julien Louis. Three weeks of a home-based “sleep low-train low” intervention improves functional threshold power in trained cyclists: A feasibility study. December 2, 2021
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17. Hearris MA, Hammond KM, Fell JM, Morton JP. Regulation of Muscle Glycogen Metabolism During Exercise: Implications for Endurance Performance and Training Adaptations. Nutrients. 2018;10(3). pmid:29498691
18. Stellingwerff T, Boon H, Gijsen AP, Stegen JH, Kuipers H, van Loon LJ. Carbohydrate supplementation during prolonged cycling exercise spares muscle glycogen but does not affect intramyocellular lipid use. Pflugers Arch. 2007;454(4):635–47. pmid:17333244
19. Psilander N, Frank P, Flockhart M, Sahlin K. Exercise with low glycogen increases PGC-1alpha gene expression in human skeletal muscle. Eur J Appl Physiol. 2013;113(4):951–63. pmid:23053125
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24. Marquet LA, Brisswalter J, Louis J, Tiollier E, Burke LM, Hawley JA, et al. Enhanced Endurance Performance by Periodization of Carbohydrate Intake: “Sleep Low” Strategy. Med Sci Sports Exerc. 2016;48(4):663–72. pmid:26741119