Athletes need to consume a diet that meets their energy, macronutrient and micronutrient requirements, and maximises their exercise outcomes and recovery. The optimal sports nutrition plan for each athlete will change from day to day to accommodate changes in training, goals and other factors impacting on the athlete. However, there are some broad recommendations for what to eat and drink before, during and following exercise, and these will be the focus of this chapter. The International Society of Sports Nutrition position stand (Kerksick et al. 2017) on nutrient timing was updated in 2017, and their position is considered in this chapter.
More specific recommendations, where available, are discussed in the following chapters, which focus on sporting categories: Endurance (Chapter 14), Strength and power (Chapter 15). Additionally, the emerging trends of macronutrient periodisation, ‘training low’ and fat adaptation are discussed in more detail in Chapter 9.
LEARNING OUTCOMES
• understand the current recommendations for nutrient intake and hydration prior to, during and following exercise
• be able to suggest practical meal and snack ideas to athletes suitable for before, during and after exercise
• appreciate that all individual athletes are different, and there is no one-size-fits-all approach to exercise nutrition.
GENERAL EATING FOR TRAINING AND EXERCISE
As discussed in previous chapters, it is critical that athletes consume appropriate intakes of energy, macro- and micronutrients for training and competition, to have appropriate energy and substrate availability for the exercise that they undertake and to enable tissue growth and repair. This means that it is important to consider their overall diet quality, and not solely what they eat before, during and after exercise. There are general macronutrient intake recommendations for athletes, which are summarised below.
Substrate
The substance, in this case the macronutrients carbohydrate, fat and protein, on which enzymes work.
Fat intake recommendations for athletes are consistent with public health guidelines and should be individualised based on training level and body composition goals.
Carbohydrate requirements vary greatly based on the type and intensity of sport/ exercise (Burke et al. 2011):
• Light exercise: 3–5 g/kg of body mass (BM) per day
• Moderate intensity: 5–7 g/kg BM/day
• High intensity: 6–10 g/kg BM/day
• Very high intensity: 8–12 g/kg BM/day.
Protein requirements also vary, with current data suggesting that the level of intake necessary to support metabolic adaptation, repair, remodelling and for protein turnover in athletes is likely higher than previously recommended, as studies’ previous recommendations were based on used methods which are now known to underestimate protein needs. The latest International Society for Sports Nutrition position stand on protein and exercise (Jäger et al. 2017) suggests that:
• Daily intakes of 1.4 to 2.0 g/kg/day should be the minimum recommended amount with higher amounts likely needed for athletes attempting to restrict energy intake while maintaining muscle mass.
• Meeting the total daily intake of high-quality protein (containing essential amino acids, especially leucine), preferably with evenly spaced protein feedings of 0.25–0.40 g/kg BM/dose, approximately every 3–4 hours during the day, should be viewed as a primary area of emphasis for exercising individuals. Higher doses may be needed to maximise muscle building for older/elderly individuals.
• Consuming 30–40 grams of casein protein before sleep can lead to acute increases in muscle protein synthesis and metabolic rate without influencing fat breakdown.
Casein protein
Casein is a family of related phosphoproteins, which are found in mammalian milk. About 80 per cent of the protein in cow’s milk is casein.
EATING AND DRINKING BEFORE EXERCISE
The key goal of eating and drinking before exercise is to optimise fuel and hydration levels and to make an athlete feel well-prepared for the exercise ahead. There is also now evidence that the nutrients consumed prior to exercise may impact on muscle protein synthesis following exercise.
Timing of meals
The right time to consume foods before training or competition will vary depending on when the exercise is to take place. It is generally recommended that consuming a ‘main’ meal about 2–4 hours prior to exercise will prevent any gastrointestinal issues arising; however, if an athlete is training or competing early in the day, or planning a long exercise session, then a small meal or snack 1–2 hours before exercise may be advised.
When working with individual athletes it is important to listen to their feedback regarding their preferences and past experience, as some athletes have no digestive issues (see Chapter 23) related to eating even within 15 minutes of commencing exercise, while others struggle if less than two hours has passed since their last meal. This simply emphasises that individual gastric emptying rates, as well as the type of food consumed, play an important role in what the best pre-exercise timing may be for an individual athlete.
Content of meals
It is well recognised that carbohydrate intake before exercise may provide fuel to allow the athlete to train harder or perform better during training and competition. Therefore, a meal or snack high in carbohydrate is generally recommended, as this enables the body to top-up its blood glucose and glycogen stores.
Recommendations vary regarding the amount and type of carbohydrate to consume. Low glycaemic index (GI) carbohydrates (see Chapter 4) have been promoted as a good choice, since they would be more slowly absorbed and lead to a rise in blood glucose in time for, or during, exercise; however, while some early research suggested this outcome, it has not been consistently supported by research. It appears that athletes can select whichever form of carbohydrate they tolerate best, as long as the amount they can consume is appropriate. It is also recommended that foods consumed should be those easier to digest—namely, foods lower in fat and fibre. The reason for lower fat choices is to minimise the length of time the food sits in the stomach, while the lower fibre also allows for food to transition faster, minimising risk of gastrointestinal discomfort (see Chapter 23).
The recommended amount of carbohydrate to consume before exercise sessions lasting more than 60 minutes is 1–4 g/kg BM in the 1–4 hours beforehand. However, generally speaking, for training or events lasting less than 90 minutes, the consumption of a high-carbohydrate diet incorporating 7–12 g/kg BM of carbohydrates in the 24 hours beforehand should be adequate to meet the needs of most athletes (Thomas et al. 2016).
What about protein?
While the benefits of consuming protein immediately after exercise are well known, the benefits of consuming protein prior to exercise are less clear. Recent research suggests that protein consumption before and/or during exercise may further stimulate post-exercise muscle growth. Researchers working in this space have also suggested that the consumption of protein before or during exercise may offer an even greater benefit during the early stages of recovery from more intense training sessions (van Loon 2014). The International Society of Sports Nutrition position stand on protein and exercise suggests that timing of protein ingestion should be based on individual tolerance, since benefits will be derived from intake before or after a workout (Jäger et al. 2017). Although it diminishes with time, the anabolic (muscle-building) effect of exercise lasts for at least 24 hours (Jäger et al. 2017).
Research also suggests that pre-exercise consumption of amino acids in combination with carbohydrate can achieve maximal rates of muscle protein synthesis (Jäger et al. 2017).
Fluid
As discussed in detail in the chapter on hydration (see Chapter 11), being well hydrated prior to commencing exercise is important. The current recommendation is to aim for 5–10 ml/kg BM in the 2–4 hours prior to exercise. Depending on the length of the planned exercise session, and whether food is also being consumed, water or sports drink may be the best options.
Pre-exercise meals and snacks
Some suggestions of suitable pre-exercise meals and snacks are listed in Box 10.1. These are just ideas and may not be suitable for all athletes. Athletes should be supported in developing individualised plans based on personal preferences, and these should be trialled during training.
Common problems reported by athletes
Nerves
While being nervous is not uncommon in athletes before exercise, nerves can be particularly problematic prior to competition as they can impact on the athlete’s ability to fuel up appropriately. Athletes often report lack of appetite, a feeling of butterflies in their stomach and nausea as common symptoms. It is clear that such issues can impact on an athlete’s ability to consume a suitable meal or snack prior to training or competition. Athletes should seek support to develop specific strategies to manage and overcome these challenges. This may include finding foods that might be tolerated even with nausea, such as dry toast or plain pasta, or, if pre-exercise eating is not possible, planning the meal the night before an early session to maximise nutrition and hydration status.
Box 10.1: Examples of suitable pre-exercise meals/snacks
PRE-EXERCISE MEAL (2–4 HOURS PRIOR)
• Breakfast cereal with low-fat milk
• Pancakes with jam/fruit and fruit yoghurt
• Sandwiches/rolls with meat filling
• Pasta dish with low-fat, tomato-based sauce
• Low-fat rice dish
PRE-EXERCISE SNACK (1–2 HOURS PRIOR)
• Fruit
• Fruit yoghurt
• Low-fat fruit smoothie
• Sports bar/Cereal bar
• Toast with honey/jam
• Low-fat creamed rice
PRE-EXERCISE SNACK (<1 HOUR PRIOR)
• Carbohydrate gel
• Sports bar
• Sports drink
• Jelly lollies, e.g. jelly babies
Gastrointestinal discomfort
Gastrointestinal discomfort, which may include abdominal pain, flatulence and diarrhoea, can also be caused by nerves or by some of the foods/fluids being consumed by the athlete. This topic is discussed in more detail in Chapter 23. Athletes should never be encouraged to try a new type, amount or timing of food/supplement/sports drink during a competition, and should experiment with new foods and fluids only during training sessions where they have control over the environment and situation. The drinks/foods/gels that will be provided at competitions should be identified and trialled well in advance. If these options are not well tolerated by the athlete, individual nutrition provision needs to be planned, practised and brought to the competition.
EATING AND DRINKING DURING EXERCISE
Generally speaking there are two key approaches to food and fluid provision during exercise; one aims to replace as much of the fuel and fluid used during the exercise session as possible with the aim of maximising exercise performance, and the other focuses on the concept of ‘training low’ to enhance adaptation.
Replacing nutrient and fluid loss
For exercise sessions up to 90 minutes, it is generally sufficient to simply replace fluid losses. For most athletes, water will be sufficient; however, for those athletes who are big or ‘salty’ sweaters, beverages containing electrolytes may be a better choice, particularly as sweat rates can vary considerably (from 0.3 to 2.4 L per hour). Furthermore, if athletes are training without having consumed an appropriate meal or snack containing carbohydrate leading up to the session, the consumption of carbohydrates via sports drinks is also often advised.
Electrolytes
Salts that dissolve in water and disassociate into charged particles called ions.
Stop-start sports
Sports in which the play is frequently stopped due to the ball going out of play or the referee stopping play because of violations of the rules. This includes sports like basketball and football.
For longer sessions, especially those focused on endurance-type exercise, it is important for athletes to consider their likely fluid and nutrient losses and plan suitable drinks/snacks to maintain their fuel and hydration levels and optimise the exercise session.
The recommended amount of carbohydrate to consume during training/events varies based on length and intensity, with 30–60 grams per hour recommended for endurance sports and stop-start sports lasting 1–2.5 hours and as much as 90 grams per hour (mixed-substrate) for ultra-endurance sessions/sports lasting in excess of 2.5–3 hours (Thomas et al. 2016). More details on the needs of endurance athletes, and strategies for fuelling endurance events, can be found in Chapter 14.
There are also specific recommendations from the International Society of Sports Nutrition based on the latest research (Kerksick et al. 2017).
• For extended bouts of high-intensity exercise lasting over an hour, carbohydrate should be consumed at a rate of 30–60 grams of carbohydrate per hour in a 6–8 per cent carbohydrate-electrolyte solution every 10–15 minutes throughout the entire exercise session.
• When carbohydrate consumption during exercise is inadequate, adding protein (0.25 g of protein/kg body weight per hour of endurance exercise) may help increase performance, minimise muscle damage and improve glycogen resynthesis.
• Carbohydrate ingestion throughout resistance exercise has also been shown to promote steady blood sugar levels and higher glycogen stores.
It is important to consider what the athlete will tolerate best, as some athletes have no problems consuming sports drink and a sandwich during an event while others struggle even to drink water without experiencing gastrointestinal issues. Nutrition plans should be based not only on the type and length of exercise, but also on the individual needs and preferences of the athlete.
As discussed in detail in Chapter 11, the current recommendation is to aim to consume 400–800 mL/hour of fluid during exercise, with the aim of avoiding body-water losses of more than two per cent. Cold drinks are recommended for hot conditions.
It is important to note that during exercise sessions exceeding two hours in length, gastrointestinal tolerance and availability of fluids will restrict what fluids will be accessible and tolerable to athletes. This makes it unlikely that athletes will be able to match sweat fluid losses with fluid intakes (Garth & Burke 2013). Athletes should be encouraged to commence exercise well-hydrated and to replace fluid losses after exercise.
Suitable drinks and snacks during exercise
Some suggestions of suitable snacks to consume during exercise are listed below. These are just ideas and may not be suitable for all athletes. Athletes should be supported to develop individualised plans based on personal preferences.
Suitable snacks/drinks providing 30–40 grams of carbohydrate:
• 600 mL sports drink
• 1 sports bar
• 1.5 carbohydrate gels
• 40 g jelly lollies
• 1.5 cereal bars.
Training low
The concept of ‘training low’ to enhance adaptation generally refers to training with low carbohydrate availability, but may also be practised with other nutrients. The aim of this approach is to integrate specific sessions into a training program where the standard practice of providing nutritional support to promote optimal performance is replaced by deliberately withholding nutritional support prior to and during the session. There is some evidence to suggest that the absence of certain nutrients (for instance, carbohydrate) around exercise leads to an increased training stimulus and/or an enhanced metabolic adaptation to exercise. There are numerous different ways in which athletes can ‘train low’, with different metabolic outcomes. Refer back to Chapter 9 for more detail regarding the evidence and recommendations for training low.
EATING AND DRINKING AFTER EXERCISE
The key aim of eating and drinking after exercise is to replenish the body’s fluid and fuel stores used during exercise and optimise recovery post-exercise. The provision of nutrients after exercise may also enhance metabolic adaptations to exercise.
Carbohydrates
One of the goals of post-exercise nutrition is to restore glycogen levels; this requires adequate carbohydrate intake and time. The glycogen resynthesis rate appears to be around five per cent per hour. The consumption of 1–1.2 g/kg BM/h of carbohydrate early in the recovery period (during the first 4–6 hours) has been shown to be effective in maximising refuelling time between workouts (Thomas et al. 2016).
Protein
Research has shown that the consumption of high-quality protein sources (0.25 g/kg BM or an absolute dose of 20–40 grams), rich in essential amino acids, within two hours of completion of exercise results in increases in muscle protein synthesis. (Jäger et al. 2017).
What about if rapid recovery is needed?
During times of intensive training or competition, rapid recovery and restoration of glycogen stores may be required. Where there is less than four hours of recovery time available, the following strategies—as recommended by the International Society of Sports Nutrition based on current research—should be considered (Kerksick et al. 2017).
• Intensive carbohydrate refeeding (1.2 g/kg BM/h) with high glycaemic index carbohydrates (see Chapter 4).
• Consumption of caffeine (3–8 mg/kg BM).
• Combination of carbohydrates (0.8 g/kg BM/h) with protein (0.2–0.4 g/kg BM/h).
Fluid
Hydration and rehydration are discussed in detail in Chapter 11. After exercise, it is recommended that athletes replace 125–150 per cent of fluid loss. For example, if an athlete has lost 2 kilograms of weight during exercise, they should aim to consume 2.5–3 litres of fluid following exercise to replace the loss. Eating solid food at this time will help maximise fluid retention.
Box 10.2: Snack/meal options for after exercise
• Sports drink with low-fat fruit yoghurt
• Low-fat chocolate milk
• Liquid breakfast substitute drinks
• Fruit smoothies made with low-fat milk/yoghurt
• Pancakes with fruit and low-fat yoghurt
SUMMARY AND KEY MESSAGES
After reading this chapter, you should understand that the athlete’s general nutrition is important for optimal health and wellbeing and poor general nutrition choices will impact on exercise performance. Making appropriate choices throughout the day, as well as optimising food and fluid intake around exercise, will help the athlete to undertake quality training sessions. The aim of food and drink consumption prior to exercise is to optimise fuel and hydration levels and enable an athlete to feel prepared for exercise. During exercise, the key objective is to try to manage the fluid loss and refuel with carbohydrate to maintain blood glucose levels and train harder or perform better. Following an exercise session, the aim is to refuel, rehydrate and enhance recovery or adaptation. Nutrition plans should be developed using the most suitable choices based on athletes’ specific requirements and personal dietary preferences.
Key messages
• Athletes’ general diets are most important for optimal health and exercise performance.
• Training and competition nutrition should be planned in accordance with the individual athlete’s training, goals and preferences.
• Nutrition should be provided before exercise to be well hydrated with full glycogen stores.
• During exercise, athletes should aim to top-up as much lost fluid and carbohydrate as possible, or utilise appropriate ‘train low’ techniques.
• After exercise, athletes should aim to rehydrate and refuel in time for the next exercise session, as well as consume the appropriate type and amount of nutrients to support metabolic adaptation and muscle growth.
Burke, L.M., Hawley, J.A., Wong, S.H. et al., 2011, ‘Carbohydrates for training and competition’, Journal of Sports Sciences, vol. 29, suppl. 1, pp. S17–27.
Jäger, R., Kerksick, C.M., Campbell, B.I. et al., 2017, ‘International Society of Sports Nutrition position stand: Protein and exercise’, Journal of the International Society of Sports Nutrition, vol. 14, suppl 2, p. 20.
Garth, A.K. & Burke, L.M., 2013, ‘What do athletes drink during competitive sporting activities?’, Sports Medicine, vol. 43, no. 7, pp. 539–64.
Kerksick, C.M., Arent, S., Schoenfeld, B.J., et al., 2017, ‘International Society of Sports Nutrition position stand: Nutrient timing’, Journal of the International Society of Sports Nutrition, vol. 14, suppl. 2, p. 33.
Thomas, D.T., Erdman, K.A. & Burke, L.M., 2016, ‘American College of Sports Medicine Joint Position Statement. Nutrition and Athletic Performance’, Medicine & Science in Sports & Exercise, vol. 48, no. 3, pp. 543–68.
van Loon, L.J., 2014, ‘Is there a need for protein ingestion during exercise?’, Sports Medicine, vol. 44, suppl. 1, pp. 105–11.