In part 2 of this mini-series, we explore:
- The Low/No-Carb vs. High-Carb debate
- Why athlete’s diets should be periodized, along with their training
- Why nutrition may be more important than the training stimulus itself
- How the type and timing of nutrition and training can be adjusted to maximise adaptations and facilitate optimum performance
- ‘Performance’ phases vs. ‘Adaptation’ phases in training and nutrition
- How ‘training low’ and fasted training may enhance adaptations and even ‘remodel’ muscle in favour of using fat as a fuel.
Producing Highly Functional Athletes
In the words of Nigel Mitchell, Team Sky’s Head of Nutrition, the aim of a nutritional strategy is to get:
“Highly functional athletes, who can recover on a daily basis, with low body mass and be able to conduct the work they need to do.”
In part 1 of this mini-series we explored how training and nutrition provide the signals and building blocks to improve performance and enhance adaptations to training, but how can we optimize both the signals and the blocks?
Periodized training may be defined as the systematic planning of training involving progressive cycling of various aspects of a training program. Periodization typically divides the year into phases: offseason, preseason, inseason, and the postseason, which focus on different goals.
Most athletes are familiar with the idea of ‘periodized training’, but the concept of periodizing nutrition is less well known. However, as suggested by Dr. Morton during the WCSS conference, nutrition may be more important than the training stimulus itself, so it makes sense to adjust an athlete’s nutritional strategy according to the phase of the athlete’s training and their specific goals.
“Although the nature of the training stimulus (i.e. intensity and duration) is important in determining how we respond to exercise training, the nutritional status of the muscle before, during and after exercise can be the dominant factor in enhancing or blunting training adaptations and competition performance” Dr. James Morton (WCSS 2014)
Polarizing Nutritional Debates, 140 Characters At A Time
The lack of awareness of periodized nutrition, combined with a tendency for the media to polarize debates and look for ‘black and white’ or generalized recommendations means that approaches to nutrition seem to generate a heady mix of controversy and evangelical followings. The controversy surrounding carbohydrate’s role in diet and exercise is one of the more well publicised debates and has resulted in the high visibility of two competing factions: low-carb vs. high-carb. The debate is further muddied by the crossover in reporting between research and comments that have been made in the context of a sedentary or athletic population, respectively. It has all the ingredients to cook up a confusing controversy and it’s easy to get caught up in it.
For the purposes of this article, I’m going to concentrate on a performance rather than health context, specifically road cycling events requiring both endurance and frequent and sustained high-intensity glycolytic (requiring the breakdown of glucose and other sugars) efforts, and avoid the HFLC (High-Fat Low Carb) LFHC (Low-Fat High Carb) debate. I’m also going to massively over-simplify the carbohydrate debate, so forgive me, but essentially, I’ll view it through the lens of:
The Low/No-Carb Crew vs. Carb Kings
Some members of the ‘Low/No-Carb Crew’ believe that we need very little or even no carbohydrate in our diet, suggest that the body can become adapted to perform very well without it and may even be healthier as a result. This may be true in some contexts.
Some members of the ‘Carb Kings suggest that carbohydrate is essential for high-performance and that removing or significantly reducing it’s presence in our diets could be detrimental to performance. This may also be true in some contexts.
As with any extreme position, there are a number of issues:
- Many of these arguments are carried out through the medium of twitter; it’s difficult to convey subtlety, nuance and a range of perspectives in 140 characters, which tends to inflame and polarize the debate further.
- Some commentators are trying to take dietary research and recommendations which have been made for a largely sedentary general public and apply it to a population engaged in endurance exercise for performance, whose needs and responses are likely to be very different.
- Responses to nutritional approaches are likely to be individualised and exhibit high variability, making generalizations difficult to justify.
- Many commentators and observers seem not to have realised two seemingly opposing truths can both be right, and wrong, depending on the timing and context.
There seems to be merit in both the low-carb and higher-carb approaches. One of my friends, Martin MacDonald (a clinical performance nutritionist), made a comment which has stuck with me: “carbohydrate is a powerful tool”. It appears that this approach has also been adopted by Team Sky and other pro-cycling teams. Nigel Mitchell talks about creating a “controlled carbohydrate environment”. Carbohydrate is an important building block for adaptation and an effective tool for the performance cyclist. Controlling carbohydrate consumption in terms of type, quantity and timing can be used to alter the nutritional status of the muscle before, during and after exercise. Through this approach, training adaptations may be enhanced and race-day performance can be powerfully influenced.
Nutrients Are Part Of Our Stimulus & Signaling System
Nutrients are more than just building blocks, they are part of the stimulus and signaling system which creates a ‘metabolic performance environment’. A nutritional strategy should reflect the goals of the training or competition phase, creating the signals which drive and enhance the adaptations we are looking for in training and facilitate optimum performance on race day. Consequently, it’s helpful to split an athlete’s approach to nutrition into two distinct phases: ‘performance phases’ and ‘adaptation phases’.
Performance Phase: Race Nutrition
The potential for carbohydrate consumption to improve performance in endurance events has been extensively researched. Stellingwerf & Cox (2014) conducted a systematic review of 61 studies on carbohydrate and endurance performance, representing 679 participants, and concluded that 82% demonstrated statistically significant improvements in performance. The consumption of carbohydrate before, during and after races is an important element in a pro-cyclist’s nutritional strategy.
In part one, we looked at Vincenzo Nibali’s race winning effort on stage 2 of the Tour de France. During the stage, he climbed the ‘Cote de Holme Moss, maintaining 400 watts for over 12 minutes. This effort came after 143 km of racing and would have been fueled predominantly by carbohydrate, in the form of stored glycogen. If Nibali’s reserves were already depleted by this point in the race, he would have been dropped by his compatriots and would never have been in a position to make his race winning effort in the finale. Ensuring that glycogen is preserved is a combination of training and carbohydrate consumption during the event, often around 60 grams per hour, or more.
Nutritional Strategies During A Tour de France Stage vs. A Single-Day Race
During the WCSS event, Omega Pharma – Quick-Step’s Professor Peter Hespel presented two in-race nutritional strategies from a rider competing in a stage of the Tour de France vs. a single-day race. Comparing these two tables, it’s clear that there are similarities and differences between the nutritional strategies in a Tour stage relative to a single-day race. The quantity and timing of the carbohydrate is similar and both strategies suggest that the ingestion of solid food should taper off, while fluid based carbohydrate consumption increases. Notably, riders in the Tour de France consume more ‘real food’, as represented in the addition of the fat and protein elements in the tables. This food provides additional calories and nutrients to support the multiple consecutive days of riding, as well as a psychological boost for the riders, which may be more important! The two tables also illustrate how nutrition should be individualised and specific to the event.
Single-Day Race Nutrition
Tour Stage Race Nutrition
The preservation of glycogen stores during a race is one of the most significant ‘performance problems’ in professional cycling. In addition to consuming adequate carbohydrate during the stage, Nibali also needed to stimulate the adaptations required to improve efficiency and preserve carbohydrate during the training phase. This required a very different approach to nutrition.
Adaptation Phase: Training Nutrition
To return to Nigel Mitchell’s quote, pro-cycling team’s are trying to create highly functional athletes, who can recover on a daily basis, with low body mass and be able to conduct the work they need to do. Ultimately, training should result in the rider:
- Losing weight, whilst preserving lean body mass (muscle)
- Becoming more efficient at using fat as a fuel at high intensity, to preserve glycogen stores.
- Being able to produce repeated very high-power efforts.
These goals will be targeted at different times, according to the training phase. Just as nutrition is altered to suit the demands of a race, it must also be adjusted according to the performance demands and desired outcomes of training.
Whilst training in a low-carbohydrate state (i.e. not eating carbohydrate for a period of time before or during training) has gained a lot of publicity recently, it’s an approach which cyclists have adopted for generations. Anecdotes abound of professional cyclists riding for hundreds of kilometres on a double espresso alone. In addition, these rides have become popular amongst riders aiming to lose weight by creating an energy deficit in their diet.
Enhancing Adaptations To Training
A number of studies have demonstrated that periods of low carbohydrate training can enhance adaptations which result in improved fat metabolism. Hansen et al. (2005) conducted a study suggesting that scheduling periods of training in low-carbohydrate conditions could enhance adaptations. Moreton et. al (2009) suggested that reduced carbohydrate availability upregulates oxidative enzyme activity. Yeo et al. (2008) found that following training in a low-glycogen state, individuals display improved whole body fat utilization. Hulston et. al. (2010) identified that this form of training also increased IMTG (Intra-Muscular TriGlyceride) utlization.
Why Does It Work?
As we wrote about in part 1, exercise provides one form of stimulus to drive adaptation, but nutrition can provide a stimulus in itself, through its presence of absence in different types and volumes.
During the WCSS, Dr. Andrew Philip’s presentation suggested the following mechanism: Training in a low-glycogen state leads to a greater capacity to use fat stores during exercise (Philip et al., 2012). When this occurs, proteins called PPAR’s (Peroxisome Proliferator-Activated Receptors) may sense alterations in fatty acid profiles in the cell, locking the protein in an ‘active’ state which drives and enhances adaptations in the mitochondrion (Zechner et al. 2012).
The evidence is strong – training in a fasted or glycogen state appears to ‘remodel’ muscle tissue in favour of using fat as a fuel. This enhanced adaptation should help riders to produce higher power-outputs whilst predominantly using fat as a fuel, therefore preserving precious and more limited carbohydrate stores.
Reducing Excess Body Fatness
The finding that training in a glycogen depleted state may improve an athlete’s ability to ultilize body fat as a fuel source also makes the approach attracted for athletes aiming to lose excess body fatness to optimize power to weight ratio.
Despite its many potential merits, the ‘low-carb’ approach has raised a number of questions and provoked controversy in some areas. In part 3 of this series, we’ll explore some of the debates and questions in more detail:
- Problem 1: How can you ‘train-low’ as part of a hypo caloric weight/fat loss strategy whilst preserving lean muscle mass
- Problem 2: Does protein ingestion before and during training compromise the adaptive response of carbohydrate restricted sessions?
- Problem 3: How can you overcome the fact that riders often find fasted and low-carb sessions challenging psychologically, due to sensations of hunger and/or lethargy.
- Problem 4: How can you maintain training intensity when training low?
- Problem 5: How can you train fat metabolism and other energy systems at the same time?