Nutrition is one of the most important components needed to support life, it's especially important for those of us looking to push the limits of what our body’s are capable of. Nutrition is highly individualized and differs greatly from person to person, but there are a set of common practices that we can focus on to make it easier to understand.
One of the best ways to get a grasp on nutrition is to break it down into what you are using/burning in a day and what you are consuming. First let's take a look at the factors that contribute to your overall energy expenditure. Resting metabolic rate is a good place to start, it is described as the number of calories your body uses when at rest in a 24 hour window. RMR is mainly defined by age, sex and lean body mass and can be estimated this equation for Men: 88.362 + (13.397 × weight in kg) + (4.799 × height in cm) - (5.677 × age in years) and this equation for Women: 447.593 + (9.247 × weight in kg) + (3.098 × height in cm) - (4.330 × age in years), (Mifflin et al., 1990). The number you get from this equation would be a rough estimate of the amount of calories you would burn on a restful day. To calculate the rest of the calories burned you can monitor the amount of kilojoules(kj) expanded throughout a ride by using a power meter, these are roughly equivalent to a calorie. Other fitness accessories such as watches, Garmin's and trackers can also be used to estimate caloric needs. Once you have estimated your RMR, you can add your daily caloric expenditure to get a rough estimate of everything your body uses in a day. Calories will fluctuate depending on intensity and volume of training, to ensure that you are meeting your nutrition goals you can also keep track of your weight.
Now that we have a better understanding of what we are burning, it's time to look at how and what we should consume throughout the day. First let’s focus on macronutrients which are fats, carbohydrates and protein. The fulcrum of an optimized diet for performance rests on protein intake. A good starting place is between 1.2-1.4 grams of protein per kilogram of body weight daily. Once you nail this down, focus on carbohydrates, aiming for 6-10g per kilogram of body weight. The range on this can vary depending on duration and intensity of training/races, but its key to get enough as it is the body’s preferred fuel source when performance matters. The remaining calories can come from fats. To further emphasize the importance of each of these macronutrients let's take a closer look into their roles within the body.
Carbohydrates are the most important fuel source for cycling performance, they are used by mitochondria to produce ATP, which is the source of energy for all activity. All forms of carbs are eventually converted to glucose, an important currency for energy that is used and moved throughout the body in response to demands. If the body has more glucose than it needs it will store the excess energy in the form of glycogen in both the liver and the
muscles. Once these stores are full, excess glucose is converted to triglycerides and are stored as fat. In order to perform optimally in training and on race day it is vital to manage these energy stores and ensure the body has what it needs to operate. Even in short events, decreased carbohydrate intake is related to a decrease in performance, and as events get longer and glycogen stores are severely depleted the intake of carbs becomes ever more important (Baltazar-Martins & Del Coso, 2019). A study looking at how carb intake affects a 40km cycling time trial showed that even just rinsing the mouth with a CHO solute decreased overall time. Carbohydrate intake must be maintained through events to continuously renew the energy that is being depleted. A good starting point for how many carbs to consume in an hour is 60-90 grams. The rate at which you absorb carbs depends on the intensity, the more intense the riding, the slower the absorption. It takes around 15-20 minutes for simple sugars, like glucose and fructose, to be absorbed. Most cycling nutrition products use a ratio of glucose and fructose because it allows us to have a faster uptake. This is a result of the different metabolic pathways our body uses to process these two simple sugars. Glucose is sent directly to the bloodstream, fructose must first be metabolized by the liver to be converted to glucose. Previously research suggested that the gold standard was 60-90g of carbs per hour using a 2:1 glucose to fructose ratio. However new research is emerging that demonstrates that using a 1:1 ratio could increase absorption to upwards of 140g/hr. Nutrition is highly individualized and can differ greatly between athletes, some athletes struggle with GI distress if they push the upper limits of carbs/hr, while others handle it with ease. Increases fueling on the bike takes time and practice, as well as finding the right combination or type of fuel to ingest. When it comes to timing, research is showing that ingesting enough carbs almost immediately after exercise leads to the fastest glycogen resynthesize rate and leads to higher levels of uptake back into the muscles (Levenhagen et al., 2001). This is important to keep in mind if you have back to back days of intense training and wish to perform optimally with full reserves of glycogen.
Protein is another very important part of the nutrition puzzle, it is often referred to as the building blocks of the body. It makes up most of the tissues, including bone, connective tissue, muscles and even hair. It also acts as building material for enzymes, hormones and hemoglobin. Current recommendations for the average person is around .8 grams of protein per kilogram of body weight, however current research suggests a higher range of 1.2-1.4g per kg and in some cases upwards of 1.8g per kg. Protein should be spread across meals and consumed in lighter quantities within the hours leading up to an event or workout (Knuiman et al., 2018). Many high protein foods can quickly satiate you, so it is advised to take it in throughout the day as the window for uptake is typically much larger than that of glucose. To put it into more understandable metrics One large egg (50 grams) provides 6.3 grams of protein, One half of a chicken breast (86 grams) provides 26.7 grams of protein and One 7-ounce (200-gram) container of greek yogurt provides 19.9 grams.
Fat is about twice as calorie-dense as carbs and proteins, and in our current culture of high carb foods it has received a bad reputation. However, fats are extremely important as they help you absorb vitamins, produce hormones, and create fatty acids. It’s important to remember that during most of the day, we
use fat as the primary source of energy and that it isn’t until we reach higher intensity that carbohydrates become our primary fuel source. Fat metabolism has become an ever growing area of research especially in cycling because of its potential to provide such vast amounts of energy during long steady efforts.
Planning your nutrition plan before a ride or race is the best way to ensure you bring enough food with you.. A practical starting point is 60-90g of carbs per hour for rides lasting longer than an hour. This may seem like a lot if you think about it in terms of daily foods. But if you use cycling specific nutrition products you will find it much easier to ingest a high quantity. Another helpful tip is to try to spread the carbs out over the whole hour, taking some every 15 to 30 minute to keep it consistent and manageable. Something to keep in mind is that as you become a more powerful/trained cyclist you will produce more watts throughout a given ride and at some point the intensity and duration can make it impossible to end a ride with a neutral kJ in and kJ out ratio. This is where pre and post ride nutrition plays an important role, to help balance energy in and energy out.
Citations
Baltazar-Martins, G., & Del Coso, J. (2019). Carbohydrate Mouth Rinse Decreases Time to Complete a Simulated Cycling Time Trial. Frontiers in Nutrition, 6. https://doi.org/10.3389/fnut.2019.00065
Knuiman, P., Hopman, M. T. E., Verbruggen, C., & Mensink, M. (2018). Protein and the Adaptive Response With Endurance Training: Wishful Thinking or a Competitive Edge? Frontiers in Physiology, 9, 598. https://doi.org/10.3389/fphys.2018.00598
Levenhagen, D. K., Gresham, J. D., Carlson, M. G., Maron, D. J., Borel, M. J., & Flakoll, P. J. (2001). Postexercise nutrient intake timing in humans is critical to recovery of leg glucose and protein homeostasis. American Journal of Physiology-Endocrinology and Metabolism, 280(6), E982–E993. https://doi.org/10.1152/ajpendo.2001.280.6.E982
Mifflin, M. D., St Jeor, S. T., Hill, L. A., Scott, B. J., Daugherty, S. A., & Koh, Y. O. (1990). A new predictive equation for resting energy expenditure in healthy individuals. The American Journal of Clinical Nutrition, 51(2), 241–247. https://doi.org/10.1093/ajcn/51.2.241
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