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Nutrition Periodization and the Transition Cycle

Before you begin reading this article about nutrition periodization, it is important to understand that you will have to change your way of thinking before adopting the principles that are presented. You will have to relinquish your traditional thoughts of nutrition being important for endurance athletes a few days to a week prior to, during and immediately after their event. That is what I call the “old school” way of applying nutrition to training. The “new school” way is to marry the periodization concept to nutrition during a year-round training regimen. Just as there are specific physiological goals for each cycle of training, so should there be for nutrition.

For endurance athletes, their nutrition plan should support their training, not the other way around. Stated a more complex way, nutrition should support the body’s energy needs associated with the different training volume and intensity stressors throughout the training year to elicit positive physiological responses. The underlying principle is that endurance athletes should eat to train, not train to eat.

Energy Expenditure and Needs

It is important to first understand the energy demands associated with endurance athletes.

The predominant energy system for most endurance athletes is aerobic with brief, intermittent involvement of anaerobic energy systems. Actual energy expenditure depends on intensity, duration and type of exercise. Exercise intensities may range between 50-90% VO 2 max for events lasting four to 24 hours, with total energy expenditures ranging between 5,000-10,000 per day in an event such as an Ironman.

In a typical endurance event lasting longer than four hours, the exercise intensity averages <65% VO2 max, and fat will be the predominant fuel source. However, with an increase in exercise intensity, or >75% VO2 max, carbohydrate will be the predominant fuel source.

The extreme daily energy expenditure of endurance events requires a significant contribution from all macronutrient energy sources. Although fat oxidation provides the greatest relative contribution to energy expenditure during low to moderate intensities with a peak around 64 +/- 4% VO2 max and becomes increasingly important as an energy source as the length of exercise increases, exercise can only be maintained for prolonged periods without the onset of fatigue if sufficient carbohydrate is available. Despite the reports of successful performance following high-fat diets, sports dietitians currently continue to recommend that carbohydrate should be the main fuel consumed during endurance events to supplement muscle and liver glycogen stores and maintain blood glucose concentrations. While protein has made its way onto center stage as of late, it does not contribute significantly to energy levels in an endurance event unless carbohydrate stores are low. In this case, amino acid oxidation has been shown to contribute to up to 15% of total energy but decreases to 5% when overall energy intake is adequate. Athletes who follow the current guidelines of a higher carbohydrate diet before and during an endurance event will minimize the contribution needed from protein as an energy source.

Nutrition Periodization Overview

I provided background about the concept of nutrition periodization in a prior article, but I would like to introduce the basic concept again as a refresher.

Proper nutrition throughout the year will not make an athlete stronger or faster in itself, but it will provide the correct amount and timing of nutrients that will improve health, prevent illnesses and change body weight and composition - all with the end goal of improving performance. There are certain times of the year during physical periodization cycles when nutrition must change to supply the right mix of nutrients and other times when nutrition needs to be the most important factor to change body weight for health or performance reasons.

An athlete’s eating program should support the body so an athlete is able to train, not the other way around. It is the missing link that athletes need to feel better after races and set new personal records.

Each physical periodization cycle requires a different mix of volume and intensity. With that comes an increase or decrease of stress on the body and an increase or decrease in the quantity and timing of carbohydrates, protein, fat and fluids. Nutrition periodization is meant to provide the athlete with the necessary energy and fluids at the right time to allow experimentation with physical training so the athlete can come to a conclusion regarding what works best for his/her body.

Athletes must have different eating programs during each of the physical periodization cycles in order to match their energy expenditure, create a negative energy balance for weight loss or create a positive energy balance, which focuses on carbohydrates to increase glycogen storage prior to a race.

Nutrition Periodization Specifics

It has been observed that during training or competition, an endurance athlete’s eating plan may include 5-19 grams of carbohydrate per kilogram of body weight, 1.2-3.0 grams of protein per kilogram of body weight and 0.8-3.0 grams of fat per kilogram of body weight. The ranges are large because training and racing time and distance varies among endurance athletes. You could be racing a sprint triathlon, the Race Across America cycling race or an adventure race. All require a different amount of time to finish and a certain intensity that can be sustained.

Keep in mind that it has been shown the human body can absorb about one gram of carbohydrate per minute (60 grams per hour, 240 calories or about one energy bar or two energy gels) of moderately intense exercise.

Nutrition periodization is meant to help athletes achieve peak health and/or performance by making slight changes in their nutrition during each of their physical periodization cycles.

Nutrition for the Transition Cycle

The body needs the much deserved recovery from training and racing associated with the transition cycle, but it does not need the weight gain. There is absolutely no reason for endurance athletes to gain weight during this time of the year. Does it happen? Absolutely! And much too frequently, but weight gain can be prevented by simply following a few guidelines that I will detail later. First, let’s discuss the logistics of the “off-season weight gain” phenomenon.

The competition cycle (race season) is characterized by a high level of physical fitness for the endurance athlete, and often results in a high daily energy expenditure. Most athletes remain weight stable throughout their competition cycles plus or minus a few pounds, depending upon hydration status. This information is critical because staying weight stable during the competition cycle tells coaches or other health professionals that the athlete knows how to remain in calorie balance.

However, the challenge occurs when the athlete moves from the competition to the transition cycle. Volume and intensity of training decrease significantly during the transition cycle, but what is more important is that the athlete’s habit of eating five to six times per day with higher quantities of food does not change.

Behavior change is a difficult process and often takes months at the very least to impact. Yet endurance athletes abruptly change the amount and intensity of training within days of ending their competition cycle. Here lies the problem.

However, the solution is to provide athletes this information before they enter their transition cycle. This will assist them in becoming aware of their rapidly decreasing energy expenditure and continued high caloric intake. The most important change for an endurance athlete to make during this time is to change the quantity that they consume, the frequency of meals and the nutrient density of their food choices. As with any type of behavior change, implementing a plan is easy - following it is more difficult. An immediate monitoring system should be instituted between the coach/trainer and athlete.

The nutrition goals that should be emphasized during the transition cycle are:

  1. Control calories
  2. Increase variety of foods eaten
  3. Enjoy food

The objectives associated with this cycle are:

  1. Put the energy bars, gels and sports drinks in the back of the cupboard for a while to give the body a break from them. I call this the “pantry shuffle.”
  2. Re-introduce whole foods from all of the food groups to acquire vitamins and minerals from foods rather than bars, gels and drinks.
  3. Try new restaurants and foods. Be adventurous and think outside of the box. Foods prepared a different way or from a different culture are good sources of nutrients.
  4. If weight loss is wanted, be realistic. Since there is not much structure or strict training guidelines during this cycle, a weight loss of one to two pounds per week is safe and realistic.
  5. Don’t overeat. Managing the amount of calories consumed is crucial during this cycle by paying special attention to portion sizes and quantities.
  6. Don’t forget about the environment. If this cycle falls during the year when there is not much sunshine, it is common for athletes to eat more comfort foods, which can be very high in calories and tend to increase body weight and body fat.

The chart below will provide a more detailed analysis of the nutrients relative to body weight that should be consumed during the transition cycle. Remember though, ranges of nutrients exist because each athlete is significantly different, and one athlete may need more or less than another.

Cycle Carbohydrates Protein Fat
Transition 5-6 grams per kilogram of body weight 1.2-1.4 grams per kilogram of body weight 0.8-1.0 grams per kilogram of body weight

Employing the concept of nutrition periodization when working with endurance athletes will allow them to not only achieve improved health and performance, but it will also educate them about the importance of eating to support the physiological adaptations their bodies are undergoing instead of simply eating as a reward for training.