Nutrition Basics For Runners: Energy & Hydration

2022 Health and Nutrition Blog
Marleigh Hefner


A Dietitian-Approved Series for Distance Athletes

Nutrition Basics: Energy & Hydration

 

Authors: Katie Knight, Nutritional Sciences Master's Student at Texas Tech University (TTU) & Marleigh Hefner, Registered & Licensed Dietitian & Nutritional Sciences PhD Student at TTU


Introduction & Welcome


Welcome to the MileSplit health and nutrition blog series, which will be running from August to November in honor of cross-country season and it's complex challenges additional to the running aspect. In this series, we will be discussing important food, nutrition, and nutrition-related topics for high-school runners, coaches, parents, and administrators.

The series will be divided into 8 posts to provide educational but applicable information for distance runners' nutrient needs. In general, the articles will address recommendations for pre- and post-workout nutrition, a modified MyPlate for distance athletes, easy and appropriate recipes for runners, and a special topics post covering runners with diabetes, disordered eating, and addressing nutrition misinformation. The following blog post will act as an introduction, including nutrition basics with energy and hydration guidelines.


Optimal Athletic Nutrition


    Many athletes and coaches know that nutrition and overall health are essential to optimizing strength, endurance, and athletic performance. In addition to supporting strength and performance, proper nutrition provides energy, supports the immune and digestive systems, prevents nutritional deficiencies, aids in efficient recovery, helps prevent injuries, and promotes athletic longevity. Optimal athletic performance requires a diet containing the correct ratio of carbohydrates, protein, and fat, in addition to proper hydration and adequate vitamins and mineral intake. Endurance athletes have vastly different and specialized nutritional needs than the sedentary general population, and even power athletes, such as sprinters (1). 


    Aerobic & Anaerobic Energy Systems


    Becoming familiar with exercise demands through energy systems is useful to understand nutritional needs of endurance athletes. There are two main types of energy systems, which are categorized by the body's oxygen consumption. These are known as the anaerobic (meaning "without oxygen") and aerobic (meaning "requiring oxygen") systems. In the body, aerobic exercise requires sugar, then fat, to produce energy (but makes the energy more slowly). Anaerobic exercise requires almost exclusively sugar to produce energy (but makes this energy more quickly) than aerobic activity (2). Power athletes utilize primarily the anaerobic energy system which is nearly 100% anaerobic. In contrast, for endurance athletes, a 2-mile run is ~20% anaerobic and ~80% aerobic, and cross-country running is ~10% anaerobic and ~90% aerobic (2). 

      Part of the reason distance athletes have different nutritional needs than power athletes, for example, is because of the different energy systems required to complete in the sport. Distance runners tend to rely on both carbohydrate and fat stores during sustained exercise, whereas power athletes require mainly carbohydrates to fuel their exercise. We will discuss the importance of specific nutrient intake to the type and duration of exercise in later articles.


      Calculating Daily Calorie Needs


      Calculating daily calorie (kcal) needs for health and maximal athletic potential is the first step in understanding optimal nutrition for distance runners. However, it's important to note that every athlete has individualized metabolism, therefore unique nutrition needs, and general equations should be used as a guideline instead of a hard rule. Registered dietitian nutritionists (RDN's) are trained nutrition professionals who can help you determine whether these general equations are best tailored to meet the needs of an individual athlete. 

      The body is usually very effective at storing energy, but not consuming enough calories can be detrimental to health and sport performance. Over time, this can be problematic because the body will first break down stored sugar (glucose) reserves known as glycogen, then stored fat, but if desperate enough will break down muscle. Glycogen, fat stores, and muscle mass are all integral components of optimal sport performance. Calories fuel athletic performance by providing the energy to exercise-and by eating the right amount of carbohydrates, protein, and fat-can prevent muscle degradation. Athletes aiming for weight maintenance should match calorie intake with calorie expenditure. This concept is known as "calories in = calories out." One method that can be used to determine approximate daily calorie consumption is to calculate resting energy expenditure (REE), then multiply that number by an activity factor that best fits their activity levels (2). 

      Formulas like this are helpful, but they can be laborious. A more convenient way to calculate the daily energy needs of the average distance athlete is to multiply their body weight in pounds or kilograms by a constant number. For example, a registered dietitian-approved recommendation is to multiply the athlete's body weight in pounds by 17 to get the approximate number of calories needed per day. For example, an athlete weighing 130 pounds multiplied by the factor of 17 means they need to consume about 2210 calories per day. Calculating calories can also be used to determine weight loss or weight gain depending on athletic needs but remember that the athlete's health and longevity should always be the priority. Calorie calculation and tracking also may not be appropriate for every athlete, particularly those at risk for disordered eating habits or those with a history of eating disorders. We'll talk more about disordered eating in distance runners in a later blog post. 


      Calculating Daily Fluid Needs


      Hydration is another extremely important aspect of nutrition. The body uses water to help digest and metabolize food, excrete waste products, regulate electrolyte and pH levels, maintain body temperature, and help with other chemical reactions (2). Water is also required to maintain the blood plasma volume, which is necessary for proper blood flow so that oxygen can reach the organs and tissues, including the brain, kidneys, heart, and working muscles (2). We also know that if left to thirst cues alone, athletes will often be dehydrated (3). Therefore, it's important to provide athletes with fluid goals to prevent dehydration. Water needs vary depending on individual needs and can be determined through a sweat test or estimated using predictive equations (3). The easiest way to calculate daily fluid needs is through the following formula: 1 milliliter/kcal/day + 34 milliliters per minute of active training.

      For example, if an athlete needs 2210 kcal per day and trained for 30 minutes on this particular day, their baseline water needs will be 2210 milliliters/day and their additional water needs will be 2000/(34*30) = 1020. In sum, the athlete needs 2210 + 1020 = 3230 milliliters of water. However, athletes should consume more water if they are thirsty or exhibiting any signs of dehydration. Also, distance athletes may benefit from consuming an electrolyte drink during and after long runs that are more than one hour in duration to replenish lost electrolytes. The sugar in sports drinks will provide quick energy to replenish lost muscle stores of glycogen. 


      Concluding Remarks


      Distance runners can use the above formulas to calculate their daily energy and fluid needs. Then, the recommended composition of macronutrients can be calculated from the daily calorie needs. Evidence-based (meaning based off scientific studies) nutrition guidelines are used by nutrition professionals to determine a healthy diet plan containing adequate amounts of carbohydrates, protein, and fat, as well as specific vitamins and minerals, which will be discussed in the next two blog posts. 

      Correspondence: Marleigh Hefner RDN, LD (holistic.nutrition.science@gmail.com)



      References


      1. Degens H, Stasiulis A, Skurvydas A, Statkeviciene B, Venckunas T. Physiological comparison between non-athletes, endurance, power and team athletes. Eur J Appl Physiol. 2019;119(6):1377-1386. doi:10.1007/s00421-019-04128-3

      2. Fink, H. and Mikesky, A., n.d. Practical applications in sports nutrition. 5th ed. Burlington: Jones & Bartlett Learning.

      3. Godek SF, Bartolozzi AR, Godek JJ. Sweat rate and fluid turnover in American football players compared with runners in a hot and humid environment. Br J Sports Med. 2005;39(4):205-211. doi:10.1136/bjsm.2004.011767


      About the Authors:


      Katie Knight, Freelance Writer, Texas Tech University (TTU) Nutritional Sciences Master's Student 

      Katie Knight is a nutrition graduate student at Texas Tech University studying the role of a novel adenoviral protein in liver fibrosis. 

      She has produced scientific writing and has written blogs, papers, and other materials for several companies. 

      Connect with Katie: https://www.linkedin.com/in/katie-m-knight/

      Contact: Katie.Knight@ttu.edu


      Marleigh Hefner, Registered & Licensed Dietitian, TTU Nutritional Sciences PhD Student

      Marleigh is a registered dietitian nutritionist (RDN) licensed to practice in the state of Texas. She has experience as a keynote speaker at the 2022 Cross Country Coaches Association of Texas (CCAT) conference. She also works with high school cross country teams by offering nutrition workshops designed to empower athletes with the knowledge to level up their performance using the science of nutrition. Marleigh maintains her clinical skills by working per diem at an acute care facility as an RDN, as well as continuing her research endeavors for her PhD in the area of metabolic disease treatments targeting nutrition and metabolism.

      Connect with Marleigh: https://www.linkedin.com/in/marleigh-brown/

      Contact: holistic.nutrition.science@gmail.com

      CV: https://www.depts.ttu.edu/hs/ns/research/obesity_metabolic_health/M.Hefner_CV.new.pdf