Certain nutritional strategies can really support performance, recovery, and adaptation. Despite that, many athletes and coaches remain poorly aware of the role of nutrition while training and competing. Out of the athletes who are aware, many are unsure of what and when to eat to support their efforts. This article will be a guide for athletes and coaches alike on how to eat for performance, with a summarized guide at the end.
I’m sure many of you have heard of glycogen; what is it and why is it important during training and competition? Glycogen is stored in our muscles and ultimately provides glucose, an essential fuel, during exercise. Low muscle glycogen levels are consistently shown to reduce high-intensity performance and the time to fatigue. Restoring glycogen is therefore fundamental for recovery, especially when on a high training load. So how do we max out our glycogen stores and eat for performance? Before we dive into that question, let’s first explore what determines glycogen levels.
Muscle glycogen is primarily derived from carbohydrates but is largely regulated by our net calorie consumption (basal metabolic rate plus energy loss from exercise). Calorie restrictions deplete glycogen stores so calorie intake should match the demands to maximize glycogen stores; this is especially important during a training phase in order to support adaptation and recovery. Guidelines are unanimous for high-carbohydrate diets enhancing athletic performance, even in short duration high intensity exercise. Low carbohydrate diets (3–15% calorie intake) have consistently been shown to diminish both high-intensity and endurance-based performance. Higher carbohydrates are not only seen to support enhanced muscle glycogen, but also cognition (reduction in technical errors), immune function, and reduced over-training symptoms while training. In terms of glycogen, it’s clear to see the importance of both adequate calories and carbohydrates.
After a workout there is a shift from catabolism to anabolism, replenishment of muscle glycogen, increased blood flow, growth, and repair. During this time, there is an improved insulin sensitivity (increased GLUT4 (glucose carriers) to cell membranes to take in glucose) and an increase in the activity of glycogen synthase (which promotes glycogen synthesis). The body can better handle high glycemic (GI) carbohydrates during and after physical activity because of the increase of GLUT4 to membranes (stimulated by insulin). The rate of glycogen synthesis post-training has been shown to be proportional to blood insulin; therefore higher GI (speed to raise blood sugar) carbohydrates will replenish glycogen stores faster than low GI carbohydrates. If there’s a time to eat high GI carbs, post-workout is that time. The rate is increased even more when carbs are consumed with protein. Take home point: carbs are vital post workout (within the first 45 minutes) to enhance muscle glycogen and support recovery and adaptation.
Depending on your training regime, aggressive nutritional recovery strategies (especially immediately after a workout) may be important to achieve higher muscle glycogen. Athletes should select which carbohydrate they consume post-workout based on how much time they have to recover between workouts. Most athletes will be able to replenish their glycogen using a low-medium GI carbohydrate. Tables on glycemic indexes are readily available online, but keep in mind that ‘cleaner’ foods are a better option than highly refined foods like doughnuts or cookies that are low in nutrients, have a lot of additives, etc. Bananas, sweet potatoes, and dried fruits are excellent examples of ‘clean’ carbs with a higher GI.
What about protein? From the ancient Greek coaches of Olympians to today’s elite athletes, protein has been considered a key nutrient for success. The mentality was more protein equals more muscle growth and therefore more strength. For the same duration, the controversy over its importance has also been present. Protein and amino acid supplement have become a billion dollar industry. Strength/speed/power athletes were recommended 1.2–1.7g/kg per day while endurance athletes 1.2–1.4g/day; these recommendations are higher than the US recommended daily allowance, which is 0.8g/kg.
Despite the growing protein supplement industry, surveys of westernized athletes consuming adequate calories consistently show sufficient protein intakes with diet alone. Furthermore, excess protein can be detrimental to performance by replacing carbohydrates in the diet, resulting in less stored glycogen. This is heightened even more while on a calorie restricted diet. If muscle growth is a goal, as opposed to better performance, higher protein intake may be beneficial; however there is minimal convincing research showing that high protein intakes (e.g. 2-3g/kg) are necessary.
So is there any value for protein supplements in terms of performance? The answer is yes, but not for the same reason many people think (e.g. more protein=more strength). Emerging research is showing that nutrient timing is more important than overall protein intake. Although some studies have shown protein intake is important within up to 3 hours after workout, more recent studies are showing greater benefits from more immediate consumption of a higher quality protein. Some athletes might find meals immediately post workout inconvenient so protein supplements may be a beneficial alternative. Keep in mind, the quality of these supplements should be assessed (e.g. additives, source). The best dose to promote muscle protein synthesis seems to be about 20g (variable with body weight); any higher and the protein is often just oxidized and not used. The warrior protein blend from Sunwarrior is my go-to supplement and is a great option for vegans and omnivores alike. Take home point: the timing of protein consumption post-exercise, with high-quality protein, may be a better predictor of muscle mass and strength gains than an overall higher protein intake.
Pre-workout: Low glycemic (GI) (e.g. Sunwarrior Activated Barley) and high GI (e.g. banana) carbohydrates would be suitable to consume before a workout to provide both immediate and sustained energy. More recently, studies have indicated that pre-workout ingestion of protein along with carbs is advantageous for enhancing training adaptations and decreasing muscle damage. The optimal protein and carbohydrate content in a pre-workout meal depends on what your workout entails, but general guidelines recommend 1–2g of carbs/kg and 0.15–0.25g of protein/kg three to four hours before a workout.
During: As exercise increases over 60 minutes, dietary carbohydrates become more important to maintain blood glucose and muscle glycogen. The recommended intake for carbohydrates during a workout is 30–60g/hr. The addition of protein to carbohydrates, at a ratio of about 4:1 carbs to protein, has been shown to increase endurance performance even more in both the short and long term.
Post-exercise: A mix of a high quality protein (15–25 grams) and carbohydrates post-workout will maximize glycogen stores and enhance recovery. Whether you choose a supplement or food source is up to you, but keep in mind, protein and carbs should be ingested quickly after a workout—preferably within the first 45 minutes.
Burke L, Hawley J, Wong S, Jeukendrup A. (2012) Carbohydrates for training and competition. Journal of Sports Sciences, 29:sup1, S17-S27.Kerksick, C., Harvey, T., Stout, J., Campbell, B., Wilborn, C., Kreider, R., Kalman, D., Ziegenfuss, T., Lopez, H., Landis, J., Ivy, J., & Antonio, J. (2008) International Society of Sports Nutrition position stand: nutrient timing. Journal of the International Society of Sports Nutrition, 5:17.Phillips S. (2012) Dietary protein requirements and adaptive advantages in athletes. British Journal of Nutrition 108:S158–S167.Stellingwerff T, Maughan R, Burke L. (2011): Nutrition for power sports: Middle distance running, track cycling, rowing, canoeing/kayaking, and swimming, Journal of Sports Sciences, 29:sup1, S79-S89.Sweet Potato Photo Credit: Steve A Johnson via Compfight ccSee this and other articles on Jennifer Novakovich’s website JennovaFoodBlog.com
