In Chapter 9: Nutrient Timing and Training
- Everyday nutrition and training
- Fatigue and glycogen depletion
- “Burnout” and overtraining
- Nutrient timing
- A balanced, nutrient-dense daily eating plan will ensure better performance and optimal recovery.
- The timing of nutrient and fluid delivery is critical to sustain your performance.
- Add protein to your recovery meal to help rebuild and repair muscle (anabolism).
- For prolonged, strenuous exercise that’s longer than 60 minutes, consume foods or drinks that are rich in carbohydrate and contain protein within 2 hours after exercise.
- Sports bars, gels, and drinks are lightweight, portable, and easy to eat during military operations.
Training promotes changes in your body to optimize muscular strength, aerobic capacity, and endurance. You can meet your training goals with appropriate nutritional strategies. Before and after training or missions, it’s important to ensure adequate energy stores and rapid recovery so you’re ready for the next mission. This chapter will provide information about nutritional strategies to optimize your training in preparation for missions.
Everyday nutrition and training
Nutrition is a key enabler for successful military operations. Properly planned and executed, good eating practices in the field maintain and enhance operational performance and contribute significantly to mission accomplishment. In addition, well-balanced meals and snacks can support recovery by helping rebuild muscle and reduce your risk of injury. You can meet your training goals through appropriate nutritional strategies implemented before, during, and after training. But before you implement nutrient-timing practices, it’s important to focus on your everyday diet. For example, if you eat lots of highly processed foods or regularly skip meals, eating a recovery snack won’t optimize your performance. Refer to Chapter 2 for information about “fueling your tank” daily.
Fatigue and glycogen depletion
When you feel tired or lack energy, you’re experiencing fatigue. Its causes can be central (brain and central nervous system) or local (muscle). One cause of fatigue is depletion of glycogen (the stored form of carbohydrate in the body). All strenuous exercise, including endurance and resistance training—whether you’re at home or on a mission—will deplete glycogen, but fatigue is more likely to happen if you’re under-fueling your body. Under-fueling by not getting enough carbohydrates can be intentional, especially when you’re limiting calories, avoiding gluten, or losing weight. Or you might be limiting carbs unintentionally if you’re unsure how much you need to eat or if you’re skipping meals or snacks due to limited time or money. Female Warfighters are more susceptible to under-fueling than male Warfighters.
It's important to eat enough carbs every day because they feed your working muscles and help maintain blood sugar. Try to fill ⅔ to ¾ of your plate with carb-rich foods such as fruit, vegetables, whole grains, beans, and dairy to fuel your body properly. Choose a variety of fruits and vegetables to optimize your intake of vitamins, minerals, and fiber. Whole-grain breads, grains, and pastas provide more performance-boosting nutrients than white-flour and refined versions. Dairy products contribute carbs along with protein and calcium. If you don’t fuel properly, your post-exercise recovery could suffer and result in “burnout.”
“Burnout” and overtraining
The terms “burnout” and “overtraining” are concerns for competitive athletes that can apply to Warfighters as well. Burnout and overtraining might result from too little recovery time in combination with too much training. A multitude of symptoms are associated with overtraining:
- Unexplained, persistently poor performance
- Moodiness, general fatigue, depression, and irritability
- Painful muscles
- Weight loss
- Overuse injuries
- Increased susceptibility to upper respiratory infections and gut problems
The symptoms of burnout or overtraining depend on your physical and physiological makeup, types of training regimens, dietary practices, sleep patterns, and various other factors. No single test can identify overtraining, but sports-medicine specialists and researchers have identified a number of key markers that change over time. These include stress hormones, immune markers, indicators of muscle damage, compromised muscle glycogen reserves, and decreases in aerobic and anaerobic capacity. For more information, read HPRC’s “Overtraining—what happens when you do too much.”
To optimize your performance, get enough rest between workouts, and time your nutrition properly. You can view nutrient timing as 3 distinct phases:
- Pre-exercise fueling
- During exercise, when energy stores are being depleted
- Post-exercise refueling (recovery)
A pre-exercise meal or snack can provide the fuel your body needs to optimize your workout. The amount and timing of your meal or snack depend on the type, intensity, and duration of your exercise, as well as your personal preferences for food choices and pre-exercise fueling.
In general, if you have 30–60 minutes before your workout, eat a carbohydrate-rich snack. Aim for around 200–300 calories. For example, eat half a peanut-butter-and-jelly sandwich.
For exercise you expect to last more than 60 minutes, use these pre-exercise fueling guidelines if you want to be more specific: Eat 1–4 grams of carbs per kilogram (about 0.5–1.8 grams of carbs per pound) of body weight 1–4 hours before exercise.1 Adjust the timing and amount of carbs to match your schedule, activity, and preference. If you want to eat more, allow more time for digestion.
A Warfighter weighs 187 pounds and prefers to eat 2 hours before his long-distance run.
Step 1: Convert pounds to kilograms.
187 lb ÷ 2.2 = 85 kg
Step 2: Multiply weight in kg times 2.
85 kg × 2 g/kg = 170 g of carbs
In this example, the Warfighter chose a meal with 170 g of carbs 2 hours before exercise. His meal might include stir-fry with 2 cups rice, 1 cup mixed vegetables, 3 oz chicken, a banana, and one cup of 100% fruit juice. See Table 9–1 for examples of the carbs in various foods. Also, consuming up to 30 grams of protein before exercise might benefit those primarily involved in strength or power training to maximize their muscle building.2
During training is the time to find out if you need to avoid foods high in fat or fiber to reduce your risk of gastrointestinal issues.3 Experiment ahead to see what works for you; don’t wait until an event day or a mission to try new foods.
Table 9–1. Approximate Carbohydrate Content of Foods and Beverages4
|Pancakes with syrup||2 (6” diameter) with 2 Tbsp syrup||78|
|Cinnamon-raisin bagel||1 (4½” diameter)||72|
|Bean-and-meat burrito||1 medium||42|
|Pasta, no sauce||1 cup||40|
|Blueberry muffin||1 small (2–3” diameter)||35|
|Cereal, wheat flakes||1 cup||32|
|Seedless raisins||¼ cup||31|
|Sweet corn||1 cup||30|
|Potato, baked, with skin||1 small (1¾”–2½” diameter)||29|
|Banana||1 medium (7–8” long)||27|
|Apple||1 medium (3” diameter)||25|
|Oatmeal cookie||1 medium||17|
|Wheat bread||1 slice||14|
|Milk, reduced fat||1 cup||12|
* Actual carbohydrate content can vary depending on brand or preparation.
In general, consuming up to 200 mg of caffeine (amount in 16-oz coffee) approximately 30–60 minutes before an endurance event can improve performance. Caffeine intake should not exceed 600 mg in 24 hours (or 800 mg for sustained operations). For more information, read “Caffeine and Performance” from Operation Supplement Safety (OPSS).
During exercise, energy stores help provide energy to your working muscles, as muscle protein is being broken down.5 Consuming small amounts of carbs at regular intervals can enhance your athletic performance, especially when the exercise lasts longer than one hour. Water is generally sufficient for exercise less than approximately one hour. During exercise lasting longer than one hour, a fluid such as a sports drink that contains carbs as well as electrolytes can help keep you hydrated. Small to moderate amounts of carbs (30–60 g per hour) from foods or fluids can extend your endurance performance. When your exercise duration is greater than 2.5–3 hours, you might need to consume up to 90 grams of carbs per hour, depending on the intensity of the exercise.6 For exercise longer than 3 hours, Warfighters typically need to consume solid foods (such as sports gels or chews, fresh or dried fruits, and pretzels) as well as liquids to meet carb needs.
Try to eat various foods during your training to determine which ones are most suitable for you. Exercise intensity, duration, environmental conditions, and mode of exercise—whether you’re running, marching, or performing manual labor—help determine the amounts of carbs and fluid your body needs. Military Service Members should simulate mission events to determine their optimal fuel sources. Never test new foods during a mission or competition; experiment during training to find what works best for you. Keep in mind that while protein is essential to build and repair muscle, consuming protein during events doesn’t appear to improve performance.
After exercise (recovery)
After exercise, your body needs to transition from a catabolic (breakdown) state to an anabolic (build-up) one to promote recovery and restore what was depleted during exercise. Within 2 hours after strenuous exercise lasting over 60 minutes consume a balanced meal.3 Aim for carb-rich foods and fluids along with 15–30 grams of protein to help restock your fuel stores and rebuild your muscles.6-9 (If you know you can’t eat a meal within that 2-hour time frame, try to eat a snack.) Foods with essential amino acids, especially leucine6, will promote post-exercise muscle protein synthesis to rebuild and repair your muscle tissue. Foods with leucine include eggs, dairy, and chicken.
Without appropriate refueling after a hard training session or mission, your performance might be compromised, especially if a second workout or mission is going to occur within less than 24 hours.
Trail mix is a great portable, quick, nutrient-dense snack for recovery. Enjoy it with 8 fl oz chocolate milk for the right balance of carbs and protein.
Try this homemade version:
2 cups dried fruit (raisins, cranberries, blueberries, pineapple chunks, or mango)
2 cups nuts and/or seeds (peanuts, almonds, cashews, pistachios, walnuts, sunflower seeds, or pumpkin seeds)
Mix well and store in an airtight container. The serving size is ¼ cup or about one handful (20 g carb, 4 g protein).
For more meal and snack ideas, read HPRC's guide to nutrient timing.
Keep in mind that fueling and recovery occur throughout the day, not just before or after exercise. All meals, snacks, and beverages consumed during the day are part of the maintenance/recovery phase. Choose well-balanced meals and snacks with a good variety of food sources to optimize your performance. Refer to Chapter 3 for specifics on daily nutrition.
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- Karpinski, C., & Rosenbloom, C. A. (2017). Sports Nutrition: A Handbook for Professionals (6th ed.). Chicago: Academy of Nutrition and Dietetics.
- Jäger, R., Kerksick, C. M., Campbell, B. I., Cribb, P. J., Wells, S. D., Skwiat, T. M., . . . Antonio, J. (2017). International Society of Sports Nutrition Position Stand: Protein and exercise. Journal of the International Society of Sports Nutrition, 14(20), 1–25. doi:10.1186/s12970-017-0177-8
- Burke, L. (2012). New guidelines for carbohydrate intake in sport from the International Olympic Committee. SCAN's Pulse, 31(3), 7–11.
- United States Department of Agriculture Agricultural Research Service. (2016). USDA Food Composition Databases. Retrieved 26 April 2017 from National Agricultural Library https://ndb.nal.usda.gov/ndb/
- Stellingwerff, T., & Cox, G. R. (2014). Systematic review: Carbohydrate supplementation on exercise performance or capacity of varying durations. Applied Physiology, Nutrition, and Metabolism, 39(9), 998–1011. doi:10.1139/apnm-2014-0027
- Academy of Nutrition and Dietetics, Dietitians of Canada, & American College of Sports Medicine. (2016). Nutrition and athletic performance. Medicine & Science in Sports & Exercise, 48(3), 543–568. doi:10.1249/MSS.0000000000000852
- Dunford, M., & Doyle, J. A. (2008). Nutrition for Sport and Exercise (1st ed.). Belmont, CA: Thomson/Wadsworth.
- Maughan, R. J. (Ed.) (2014). The Encyclopaedia of Sports Medicine: Sports Nutrition (Vol. 19). Chichester, UK: John Wiley & Sons Ltd.
- Williams, M. (2009). Nutrition for Health, Fitness & Sport (9th ed.). New York: McGraw-Hill Science/Engineering/Math.
- Director, Operations Directorate, Joint Culinary Center of Excellence. (2012). Memorandum: Commercial Off-the-Shelf (COTS) Nutrition Supplements for Special Forces (SOF). U.S. Army Quartermaster Corps and Quartermaster School, Fort Lee, VA 28301.