Published by The Consumer Education Project of Milk SA
https://www.rediscoverdairy.co.za/dairy-and-sport-2/sport-nutrition-and-the-role-of-dairy/
Published by The Consumer Education Project of Milk SA
https://www.rediscoverdairy.co.za/dairy-and-sport-2/sport-nutrition-and-the-role-of-dairy/
1. INTRODUCTION
What athletes and players eat affects their performance, and appropriate food choices will affect how well they train and compete. Good food choices planned at the right time may have the biggest impact on training. A good diet can support consistent intensive training, optimise recovery and limit the risks of illness or injury. Good food choices can also promote adaptations to the training programme to ensure improvement in training and competition performance over time.
This booklet contains information that will help athletes and players at all levels of participation to make informed choices to meet their nutritional needs. Every athlete or player is different and there is no single diet that meets the needs of all athletes or players at all times. The booklet aims to give practical information against a blueprint of basic sports nutrition principles but is not intended as a substitute for individual advice from a qualified professional.
The booklet has been compiled as part of the Consumer Education Project (CEP) of Milk South Africa. The CEP would like to thank dietitians Nicki de Villiers and Lize Havemann-Nel for their input and for sharing their years of experience in compiling this manual.
(This document is a general guideline for learners and athletes. For personal needs, consult a registered dietitian by visiting the website of the Association for Dietetics in Southern Africa at www.adsa.org.za.)
The CEP is an initiative of Milk South Africa that was formed to communicate health and nutritional messages regarding dairy products to consumers and health professionals in South Africa. The major objectives are to address the misconceptions and lack of information regarding the nutritional and health benefits of dairy products. The project requires expert knowledge from fields such as dietetics, nutrition, dairy technology, communication, and consumer behaviour. Through appropriate structures and processes, the CEP makes use of experts in the different fields to create an integrated, multi-faceted communication campaign. ‘Good nutrition and physical activity go hand in hand.
Physical activity promotes health and fitness. The benefits ascribed to physical activity include building and maintaining healthy bones, muscles and joints. Physical activity helps control weight, builds lean muscle, and reduces fat. It can also exert a positive effect on brain health, resulting in better memory and cognitive performance and reducing the symptoms of depression. Establishing an active lifestyle throughout the younger years can also prevent the risk factors contributing to various health conditions like heart disease, obesity and Type 2 diabetes.1,2
All adolescents and young adults benefit from physical activity. It is recommended that children and adolescents do 60 minutes or more of moderate, which refers to the energy that is available to the body after the energy cost of physical activity has been deducted from the daily energy intake to vigorous physical activity daily. Aerobic activity should make up most of the 60-plus minutes of physical activity each day. Muscle-strengthening activities such as gymnastics or push-ups should be included at least three days per week. Bone strengthening activities, such as skipping or running, should also be included three days per week as part of the recommended 60-plus minutes per day.1-3
Good nutrition and physical activity go hand in hand. Two main aspects of sports nutrition require attention: the quantity and quality of nutrients. The quantity of nutrients refers to a sufficient intake of energy and optimal hydration. Quality implies the intake of high-quality nutrients like protein, calcium and other micronutrients.3
Dairy products are included in the South African food-based dietary guidelines. Milk, yoghurt, maas and cheese are good sources of calcium and protein, which are vital nutrients for bones and muscle mass maintenance. Young athletes can benefit from the inclusion of dairy products to aid in bone growth and mineralisation, which occur during infancy and childhood and lead to peak bone mass after early adulthood. A low peak bone mass can increase the risk for osteoporosis and fractures later in life. Milk, a complete food matrix, has an effect on bone and muscle health that is more than the sum of its nutrients.4
Low-fat flavoured milk and drinking yoghurt not only provide fluid but also contain calcium, protein, carbohydrates and electrolytes in an ideal combination to prevent dehydration and fatigue. Research has shown that athletes find it easier to recover from dehydration when carbohydrates are supplied through drinks that come in a variety of flavours. The intake of protein together with fluids has also been shown to be ideal to help muscles recover after exercise.
Athletes and players who take part in sport need three to four servings of dairy products a day (low-fat milk, low-fat yoghurt, maas and/or cheese).5-9
Low-fat flavoured milk or drinking yoghurt is the perfect sports drink because it:
1. contains carbohydrates to boost energy, combat fatigue, fill up fuel stores and ensure hydration;
2. contains protein to help muscles recover, giving a rich supply of easily absorbed calcium to build and maintain strong bones;
3. contains potassium, sodium and magnesium to replace electrolytes lost through sweating;
4. contains fluid to prevent heat stress and exhaustion; and
5. comes in a variety of flavours to encourage youngsters to drink enough fluids.
The foods and beverages that athletes consume will affect their performance during training and competition. Good food choices offer the following to athletes or players:
4.1 Energy
Energy intake sets the quantity (budget) from which an athlete must meet their needs for macronutrients (carbohydrate, protein and fat). At the same time, the quality and variety of foods to provide adequate amounts of micronutrients (vitamins and minerals) are equally important.3
The energy needs of an athlete are determined by the baseline metabolic needs, growth and physical activity, and based on the intensity, duration and frequency of training sessions and competition. If the amount of food an athlete or player eats is equal to the energy expenditure, the athlete or player is said to be in energy balance.11
Energy availability, on the other hand, refers to the energy that is available to the body after the energy cost of physical activity has been deducted from the daily energy intake.11
The body can cope with a small drop in energy availability, but if it becomes too great, this will compromise its ability to undertake the processes needed for optimum health and functioning.11
4.2 Fuel foods
Physical activity and sport involve muscle contraction. For the muscles to contract, energy is required and supplied through the food that we eat. Getting the right amount and type of fuel from food will help athletes train well and stay healthy.
Carbohydrates and fat are the preferred fuel sources for the working muscles, but carbohydrates are the main source of fuel.
Carbohydrates are the main fuel source for athletes, especially during high-intensity activities such as running, cycling, and squash, and team sports such as hockey, soccer, and rugby. The body stores carbohydrates in the form of glycogen in the liver and muscles. Liver glycogen is important to maintain normal blood sugar levels during exercise, and muscle glycogen is important to fuel working muscles.12
Good nutritious sources of carbohydrates are starchy foods (e.g. bread, rice, pasta, couscous, maize meal porridge, and cereals), fruit (fresh and dried), fruit juice, starchy vegetables (e.g. potato, sweet potato, corn, and beetroot) and pulses (e.g. beans and lentils). Milk, flavoured milk and low-fat flavoured yoghurt are also good sources of carbohydrates and at the same time contribute to the athlete’s protein needs. Sugar and sugary foods and drinks such as sweets, Coke and sports drinks are also high in carbohydrates and can be included as fuel sources during exercise.
Athletes generally need more carbohydrates compared to the general population. However, factors such as total daily energy expenditure, type of sport, sex, age and weight of the athlete need to be considered in estimating specific carbohydrate needs. The amount of carbohydrates is usually estimated based on the amount of exercise (taking into consideration the duration, frequency and intensity of exercise) and the athlete’s bodyweight as follows:
Try to eat five to six meals a day and include a carbohydrate food source with every meal. Athletes should also eat carbohydrates before and during hard or long exercise sessions to fuel the session, and thereafter to help with recovery.
Fat as fuel food
Fat provides more than double the amount of energy compared to carbohydrates, and the body’s fat stores are adequate to fuel many hours of exercise. However, since carbohydrates are more readily available and easier to use especially during higher intensity exercise, a high percentage of fuel comes from carbohydrates and only a small amount from fat. It is important to note that the body’s carbohydrate stores are small, so athletes competing in longer events (e.g. marathons and lengthy cycle races) will also use fat as fuel. Fat is not just a second fuel source, it is also important in an athlete’s diet as it provides fat-soluble vitamins and essential fatty acids, protects the internal organs, and keeps the body warm.
Not all fats are equal. Athletes need to include healthy (unsaturated) fats in their diets and limit the unhealthy (saturated) fats. Good sources of fat are plant-based fat sources including avocado, nuts and seeds, olives/olive oil and peanut butter. Eggs, full-cream yoghurt/Greek yoghurt also contain fat and are good sources of protein. Fatty fish (e.g. salmon, tuna, and sardines) is another protein-rich source that is high in omega-3, the heart-healthy fat.
Athletes do not necessarily need more fat compared to the general population. In fact, some athletes need to maintain a lean physique to perform well (e.g. runners and gymnasts) and should therefore carefully control the amount of fat they eat. The amount of fat is not only dependent on ideal body composition (associated with the type of sport), but also on total daily energy expenditure, the nature of the sport and the athlete’s sex. The recommended fat intake for athletes is from 20% to 35% of total daily energy intake. For an athlete weighing 70 kg, this amounts to approximately 80 g of fat per day.
The table below contains examples of good sources of fat with portion sizes that equal approximately 10 g of fat. Male athletes can choose seven to eleven servings per day, while female athletes should aim for five to eight servings per day.15
Fats/fat food sources are often combined with main meals (e.g. fish for supper), eaten in combination with other foods (e.g. butter on bread, olives in salads) or used in meal preparation (oil for frying/roasting). Athletes can also eat full-cream yoghurt, nuts and seeds, or boiled eggs as a snack in-between meals. However, fat or foods high in fat should not be eaten before or during exercise. Too much fatty or fried food on the day of a competition might lead to sluggishness. Fat decreases the transit time of food through the gut, which means that in the presence of a lot of fat, carbohydrates would not be readily available. Therefore, limit the use of fatty or fried foods on competition days.13,14
4.3 Building foods
Protein is involved in the development, growth, and repair of muscles and other bodily tissue and is therefore critical for recovery from physical activity.
Protein can also be used as a fuel; however, it is not used efficiently and therefore is not a fuel food preferred by the body. It can, however, boost glycogen storage, reduce muscle soreness and promote muscle repair. Those who are active regularly may benefit from consuming a portion of protein at each meal and spreading out protein intake throughout the day.13
Protein is found in a variety of foods, including grains and vegetables, but is mainly concentrated in milk, meat and beans (soya products, nuts, seeds, beans, and other non-animal products).13
Athletes participating in regular sport and exercise may need a higher protein intake to promote tissue growth and repair. However, it is not just the amount of protein that counts, but also when it is consumed. Protein should be consumed in the right amounts, at the right times, and when in a reasonably good energy-balanced state. Randomly eating more protein does not accomplish what the body needs.15
The protein recommendation for athletes is an intake of ± 1,2 to 2,0 g protein per kilogram body weight per day. Recent recommendations to stimulate muscle protein synthesis maximally suggest an optimal protein intake of 20 to 25 g (or the equivalent of ± 0,25 g/kg) per meal.12
It is recommended that athletes eat a building food (protein) every three to five hours throughout the day and specifically between 30 minutes and two hours after training. It is beneficial to take the building food with a fuel food (carbohydrate source).17
4. Protective food
Carbohydrates, fat and protein (fuel foods and building foods) help athletes train and compete, and repair muscle and other bodily tissue. But athletes also need to stay healthy and maintain their immune systems. Intense and continuous training causes oxidative stress, and combined with life’s other stressors (work, environment, not enough sleep, travel, and relationships) puts strain on an athlete’s immune system. A sick athlete cannot train or compete so it is important that athletes take care of their health. Although enough energy and macronutrients are also important for health, protective foods contain vitamins and minerals and other important nutrients that are especially important for the immune system (e.g. antioxidants [Vitamins C, E, and selenium], B-vitamins, Vitamin D, iron, zinc, omega-3, and polyphenols).18,19
The most important source of vitamins and minerals are fruit and vegetables. Since different colours of fruits and vegetables contain different vitamins and minerals, athletes should eat a variety of colours. The table below provides more examples of food sources for the specific nutrients that are important for a healthy immune system.19-21
Aim to eat at least five fruits and vegetables per day (including one to two green vegetables, one to two yellow vegetables and two to four different fruits). Include whole grains in your carbohydrate sources and ensure that you eat the recommended protein portions (including milk and animal proteins). If you are a vegan/vegetarian you will need to plan your food combinations carefully to ensure that you also meet your iron, zinc, and Vitamin B12 requirements.
Protective food sources such as vegetables and protein sources are ideal to include in main meals (salad during lunchtime; vegetables at supper time), while fruit and dried fruit are ideal snacks between meals.
Meal planning will help to fit all the pieces into a beautiful puzzle that supports training and competition performance. Herewith is a review of the basic principles:
Eat something within an hour of waking up. Eating breakfast on a consistent basis tends to result in a better nutritional profile and a lower risk of becoming overweight. It may also improve cognitive function.22
Keep the meal balanced: combine a fuel food (carbohydrate in starch) with a building food (protein) and a protective food (fruit or vegetable). Remember the intake of fluid with this meal.
Eat a snack or a meal every two to three hours for better blood glucose control. Keep snacks small and nutrient-rich. Remember to include a building food (protein) as part of the snack.15,23
Main meals (lunch and supper) should include a fuel food (carbohydrate source), a building food (low-fat protein choice) and a generous helping of protective food (vegetables or salad).
Drink fluids like water, milk, fruit juice or iced tea throughout the day.
Be sure to eat fuel food (carbohydrate-rich snacks) before training.12,15
For training sessions that last longer than 60 to 90 minutes, drink a carbohydrate-based drink during the session.12,15
Eat a recovery snack as soon as possible after the training session. Be sure to include fuel foods (carbohydrate source), building foods (protein) and liquid.12,15
*Carbohydrate portions *Protein portions *Add some vegetables to help fight flu or other infections!
Water is essential to life and has many important roles in the body. It maintains blood volume and regulates body temperature, and during exercise, the body cools itself by sweating. Sweating ultimately results in a loss of body water and potentially some electrolytes, which, if not replaced, can lead to dehydration and compromised performance. Therefore, athletes should make sure that they prevent dehydration by drinking enough fluid.
Sweat losses usually increase with an increase in exercise intensity, temperature and humidity. Athletes performing high-intensity exercise in hot weather should therefore pay special attention to replace fluid losses. In cool weather or when the exercise intensity is low, sweat loss may be small. Similar to not drinking enough fluid, drinking more than necessary can also interfere with performance and can be dangerous to health. Drinking too much fluid (or over-hydrating) during exercise can dilute the levels of sodium in the bloodstream resulting in hyponatraemia. Both dehydration and hyponatraemia should be prevented during exercise and athletes should aim to maintain optimal hydration status.
Dehydration results in an increase in heart rate and body temperature. There is also an increased perception of how hard the exercise feels, especially when exercising in the heat, resulting in a reduction in physical and mental performance (including concentration and decision-making). Dehydration can also increase the risk of nausea, vomiting, diarrhoea and other gastrointestinal problems during and after exercise.25,26
The past decade has seen controversy over guidelines for fluid intake during sport. Fluid requirements differ for different sports, but also for different individuals participating in the same event on the same day. What is clear is that fluid needs are highly individualised and there is no one-size-fits-all approach to fluid intake. Fluid intake depends on fluid/sweat loss, so athletes should be able to monitor their own hydration status in order to adjust fluid intake accordingly.25,26
Athletes can start to monitor their day-to-day hydration status when waking up every morning. Three easy indicators to monitor include body weight, urine colour and thirst. A daily loss of more than 0,5 to 1,0 kg of body weight, a small volume of dark-coloured urine (like apple juice or darker), and the noticeable sensation of thirst are all symptoms of dehydration. When two or more of these symptoms are present, dehydration is likely. If all three markers are present, dehydration is very likely and greater attention should be given to 24-hour fluid intake.27
A change in body weight is also an indication of an athlete’s hydration status following exercise. The percentage change in body weight can be calculated as follows:
Drinking fluid during exercise is necessary to replace the fluid lost through sweat. The amount of fluid consumed should therefore reflect the amount of fluid lost through sweat. As sweat rates vary among individuals, knowing your unique sweat rate and how much fluid you should be drinking is important.
There are many fluid options available, and it is important to determine what works best for you as an individual. Plain water can be an effective drink for fluid replacement, especially in low intensity and short duration sport. If you prefer an alternative, consider consuming a diluted sports drink or diluted fruit juice (two cups of water, one cup of fruit juice). Sports drinks (6% to 8% carbohydrate solution) can be useful during some activities, especially high-intensity or endurance sport, as they contain both carbohydrates for fuel and flavour, and electrolytes (sodium) to help the body ‘hold on to’ fluid more effectively and stimulate thirst. During ultra-endurance events, athletes may prefer to consume water and food; not only to match fluid to required energy intake but also to use the water to cleanse the mouth of flavours that can become unpleasant after prolonged consumption.12,26
Exercise requires energy, and in the section on fuel foods, we had a look at carbohydrates as the main fuel source during exercise. In some instances, athletes may prefer to train with a low carbohydrate availability (e.g. train early in the morning without eating a pre-exercise snack or meal) to benefit from specific training adaptations (e.g. improved fat oxidation). The choice of pre-exercise carbohydrate intake does not only depend on the intensity and duration of the session, but also on what the athlete wants to achieve with the specific exercise session (e.g. a faster time or improved performance vs. the activation of acute cell-signalling pathways). In some instances, athletes may not only benefit from a pre-exercise meal in the hours before the event to replenish liver glycogen stores, they may also benefit from a high-carbohydrate diet in the days leading up to the event (i.e. carbohydrate loading) to maximise muscle glycogen stores.28
Athletes taking part in activities likely to involve continuous exercise for more than 90 minutes, or activities that involve repeated high-intensity exercise bursts can consider carbohydrate loading. By maximising muscle glycogen stores, carbohydrate loading can help to postpone fatigue and maintain a higher work pace during exercise. However, athletes should experiment with carbohydrate loading before training sessions of a longer duration since it results in slight weight gain (additional water is stored with glycogen). Athletes may also experience gastrointestinal discomfort during the loading phase if they are not used to eating a high volume of carbohydrate-rich foods (like refined carbohydrates).
It is important to note that even if athletes are carbohydrate-loaded, they still need to eat additional carbohydrates during endurance and particularly ultra-endurance events to maintain normal blood glucose levels. Carbohydrate loading also does not increase performance when high carbohydrate availability is maintained with a pre-exercise carbohydrate meal and adequate carbohydrate ingestion during exercise. Athletes who experience discomfort with carbohydrate loading can therefore aim to normalise their muscle glycogen stores by including regular carbohydrate meals and snacks (as per their normal training diet) the day before. The inclusion of a pre-exercise meal and enough carbohydrates during the event is then very important (intake during exercise will be discussed in the next section).
Athletes taking part in endurance events or training sessions of longer duration (> 90 minutes) with the aim to perform, as well as athletes taking part in shorter high-quality training sessions or matches (where it is important to maintain a certain exercise intensity) should eat a pre-exercise meal to ensure that they start the event with enough fuel. The aim of a pre-exercise is not only to fuel muscle and liver glycogen stores but also to ensure that the athlete is well-hydrated. A pre-exercise meal can also prevent hunger and avoid gastrointestinal discomfort during the event and have psychological benefits.12
NOTE: For any individual differences or needs required for a specific sport, it is recommended to contact a professional dietitian to assist you with your personal meal plan.
The main considerations from a nutritional point of view are to maintain energy levels and hydration levels (refer to the hydration section for details on hydration). The body’s carbohydrate stores (liver and muscle glycogen) provide an important but fairly limited supply of energy during exercise. Athletes may choose to train with a low carbohydrate availability and not only skip the pre-exercise meal but also refrain from consuming carbohydrates and fluid during exercise to benefit from specific training adaptations. The choice of consuming carbohydrates during exercise mainly depends on the intensity and duration of the session, but the specific training adaptation that an athlete wants to achieve with the training session must also be considered (e.g. a faster time/improved performance vs. the activation of acute cell-signalling pathways).28
During very high-intensity exercise, the athlete predominantly uses carbohydrates as fuel. The liver glycogen stores that are responsible for maintaining normal blood sugar levels during exercise can be depleted within one to two hours of moderate to high-intensity exercise. Adequate carbohydrate intake during exercise can prevent hypoglycaemia and muscle breakdown when carbohydrate stores in the form of glycogen become depleted. Carbohydrate intake during exercise is also the best-proven strategy to enhance performance since it spares endogenous glycogen levels and helps athletes to sustain a higher exercise intensity. Even athletes who just rinse their mouths with a carbohydrate drink during exercise can benefit from the positive effects of ‘mouth sensing’ on the central nervous system.
Athletes taking part in endurance events or training sessions of longer duration (> 60 to 90 minutes), or in shorter events (45 to 75 minutes) with repeated intermittent high-intensity bouts (e.g. team sport including soccer, hockey, or rugby) should consider consuming carbohydrates during exercise. Sufficient carbohydrate intake during exercise is even more important when athletes start the event with low liver and muscle glycogen levels (i.e. if they did not eat a pre-exercise meal or normalised/maximised their muscle glycogen levels). Endurance and ultra-endurance athletes who aim to enhance their ability to consume and use more carbohydrates during events should train with a high carbohydrate availability and consume sufficient amounts of carbohydrates during training to train the gut.30
An increase in training load is associated with an increase in fitness level, but what is often overlooked is that real gains in exercise capacity occur when the body is at rest and able to recover. Recovery aims to maintain the athlete’s physical and mental readiness to perform. Recovery nutrition promotes muscle regeneration, glycogen restoration, reduces fatigue and supports physical and immune health, helping the athlete to prepare for the next competition or training session. Each training session is different regarding sweat rates, muscle fuel depletion, protein synthesis stimulation and damage or disruption incurred.12,32,33
Carbohydrate intake after a training session aims to restore depleted muscle and liver glycogen stores.
Refuelling is highly dependent on the extent of glycogen depletion (glycogen that was used) and the type, duration and intensity of the exercise.
Mix-and-match meal examples:
When exercise intensity is low to moderate, exercise duration is short (< 90 min), and when there is ample time before the next exercise occasion (>8 h) less emphasis is placed on optimising carbohydrate guidelines for recovery in team sport athletes. In such scenarios, regularly spaced and nutrient-dense meals are likely to be sufficient to meet the recovery demands of the athlete.
Protein in the recovery meal facilitates muscle repair, muscle remodelling and immune function. Multiple factors modulate the response of muscle protein synthesis to protein intake, namely:
Rapidly digested protein sources (high in whey) that are particularly suitable for a post-exercise protein boost include the following:
Rehydration is an important part of the recovery process, particularly when athletes need to participate in a subsequent exercise session within a short period (e.g. two sessions per day or when playing tournament matches).
YOUR ROAD MAP TO RECOVERY
REMEMBER
If training only in the afternoon, the morning snack (before or during training) will fall away. When training only in the morning, move the afternoon snack a bit later, e.g. to 16:00. Take note that the snacks during training and recovery will then fall away but you will still have your normal supper and a late-night snack.
The following combinations provide ± 60 g carbohydrates and ± 10 g protein:
10.1 How can a balanced diet enhance an athlete’s performance?
Numerous factors contribute to success in sport, and diet is a key component. An athlete’s dietary requirements depend on several aspects like the sport, the athlete’s goals, the environment, and practical issues. Specific dietary advice suited to the individual is increasingly being recognised, including day-to-day advice and specific advice before, during, and after training and/or competition. Recent research into energy availability shows the negative physiological and performance effects when training with low energy availability. Therefore, it is crucial that athletes make sure they get adequate energy intake to support training loads for optimal health and functioning.11 Optimal carbohydrate availability is a key strategy for many athletes. Recent research investigated the concept of periodised training with the emphasis on ‘eat for what you are going to need’. This places dietary strategies at the core of training session outcome goals.12,13
Carbohydrate intake during exercise maintains high levels of carbohydrate oxidation, prevents low blood sugar (hypoglycaemia), and has a positive effect on the central nervous system. Recent research has focused on athletes training with low carbohydrate availability to enhance metabolic adaptations, but whether this leads to an improvement in performance is unclear.
The benefits of protein intake throughout the day following exercise are well recognised. Athletes should aim to maintain adequate levels of hydration, and they should minimise fluid losses during exercise to no more than 2% of their body weight.12
A balanced diet consisting of the following components will enhance sports performance:
During times of high-intensity training, an athlete needs adequate energy intake to maintain body weight, maximise training effects, and maintain good overall health. Carbohydrates are the main fuel source for athletes, who need larger amounts than the general population. However, factors like total daily energy use, type of sport, sex and age of the athlete, and environmental conditions need to be considered to estimate carbohydrate needs. Carbohydrate intake before and during exercise delays fatigue. It enables athletes to train for longer and increases carbohydrate oxidation to help maintain a higher intensity or to maintain their pace. Rinsing the mouth with carbohydrates during training can also lessen the perception of fatigue. It can therefore be used to minimise gastrointestinal symptoms due to carbohydrate ingestion.
Protein helps the muscle to recover
Protein requirements are higher for very active people. Protein intake will help the muscle to recover from damage brought on during training, and enhance muscle protein synthesis.13,14 Proteins should be consumed in the right amounts, at the right times and when in a reasonably good energy-balanced state. Randomly eating more protein does not meet the body’s needs.15 The requirement can be met through diet alone, without using protein supplements.13,14
Fat is important in an athlete’s diet as it provides energy, fat-soluble vitamins and essential fatty acids. It should make up no less than 20% to 30% of an athlete’s total daily dietary intake. For an athlete weighing 70 kg, this amounts to ± 80 g of fat a day. Too much fatty or fried food on a competition day might lead to sluggishness. Fat decreases the transit time of food through the gut, which means that in the presence of a lot of fat, carbohydrates are not readily available. Therefore, limit the use of fatty or fried foods on competition days.13,14
Dehydration decreases exercise performance. It is important for athletes to consume adequate fluids before, during and after exercise to maintain optimal hydration.13,14
10.2 How can dairy products aid muscle recovery after sport?
Post-exercise recovery is a multifaceted process that will vary depending on the type and duration of the exercise, the time between exercise sessions, and the goals of the exerciser. The main nutrition considerations are:
Research has shown that drinking milk after exercise can be beneficial for acute recovery and chronic training adaptation. Milk enhances muscle protein synthesis after exercise and decreases post-exercise muscle soreness.35
Skeletal muscle is important for athletes due to its important role in movement, strength and metabolic regulation. Optimising skeletal muscle mass is important for health and performance. Exercise stimulates muscle building, but the process needs appropriate protein intake to optimise muscle protein synthesis. The source, amount and pattern of protein intake after exercise influence this synthesis. An intake of 20 g of high-quality protein can be enough to maximise muscle protein synthesis after exercise. A litre of milk contains ± 36 g protein, which means that ± 600 ml should be adequate to maximise muscle protein synthesis. The high essential amino acid and leucine content of milk helps to maximise muscle protein synthesis and can reduce muscle soreness after some form of exercise.35
10.3 What if an athlete needs to lose weight while training? (and a few words on intermittent fasting)
Many athletes aim to lose weight for aesthetic reasons (i.e. gymnasts), to ‘make weight’ for competition (i.e. combat sports) or to optimise their ratio of strength, power, or endurance to bodyweight for performance advantage. Optimal training requires energy, while weight loss often requires a restriction of energy intake. How can athletes maintain their energy levels during training, especially during endurance training, and at the same time create a big enough energy deficit to lose weight? More importantly, how can athletes lose unwanted fat mass, without losing muscle mass (referred to as high-quality weight loss). There are a number of major dietary strategies to optimise weight loss and performance in athletes, ranging from low-fat to low-carbohydrate/ketogenic diets. Intermittent fasting (IF) is also one of these major dietary strategies and has recently received a great deal of attention.36
A few words on intermittent fasting37,38
Intermittent fasting (IF), also known as intermittent energy restriction, is an umbrella term for various meal-timing methods. The emphasis of IF is on restricting the feeding time-window, rather than restricting energy intake. IF consists of a combination of voluntary fasting (usually > 12 hours) and non-fasting (re-feeding) over a given period. The method that is receiving the most attention from athletes is ‘time-restricted feeding’ (TRF), also known as the ‘16:8’ method. This method recommends fasting for 16 hours and shortening the duration of the daily eating window (during active daylight) to a maximum of 8 hours, without altering energy intake or diet quality. TRF can include food intake during the first half of the day (06:00 to14:00 = early time-restricted feeding [eTRF]) or during the second half of the day (12:00 to 20:00 = delayed time-restricted feeding [dTRF]).
IF induces fat loss, and is an attractive weight loss option since only the time of food consumption is restricted (no calorie-counting or adhering to difficult diets). Eating according to circadian rhythm (during active hours of the day when the sun is up) has also been shown to improve metabolism, blood sugar control, and cholesterol and triglyceride levels in overweight and obese individuals. It is important to note that most studies evaluating the effects of fasting on weight loss and athletic performance use different fasting regimes and protocols and vary in their outcomes. Data on athletes from the majority of studies are based on Ramadan data/overnight fasts that were < 12 h, with limited studies employing the TRF protocol (16:8 method). Although limited emerging evidence suggests that there may be a use for time-restricted feeding (combined with resistance training and high protein intake to preserve muscle mass and improve body composition), no performance benefit has yet been shown.
During the past decade, knowledge about the specific role of protein to manipulate body composition and attain high-quality weight loss has evolved considerably. Fat and carbohydrate (the body’s main fuel sources) intake needs to be carefully manipulated to create an energy deficit. But high-quality weight loss also requires adequate intake of high-quality protein distributed evenly and frequently in relation to exercise and recovery.39
10.4 How can sports drinks support training or performance?
Sports drinks (carbohydrate energy drinks) can be very useful for athletes participating in high intensity or endurance sport, as it contains both carbohydrate for fuel and flavour and electrolytes (sodium) to help the body ‘hold on to’ fluid more effectively and also stimulate thirst. In fact, carbohydrate energy drinks are the best proven ergogenic aid. However, sports drinks – whether homemade or commercial – should only be consumed during activity as they are a high-energy source specifically formulated to fuel the active body.
The fluids that sports drinks provide during exercise are important to replace fluid losses, prevent dehydration and help cool the body. Flavourings encourage regular drinking.
A 6% carbohydrate solution (6 g carbohydrate per 100 ml drink) strikes the optimal balance in taste, rapid fluid absorption and energy supply for working muscles. Undiluted juice or carbonated drinks should be avoided because they typically contain too much carbohydrate (10% to 12%) and may cause gastric discomfort and delay gastric emptying. Multiple carbohydrate sources are preferred because this helps stimulate fluid absorption.
The electrolyte content of a sports drink should attempt to replace both the potassium (30 mg/250 ml) and sodium lost through sweat. A potassium concentration of 30 mg/250 ml should be adequate. Sodium intake of approximately 100 mg/250 ml enhances the taste of a sports drink, facilitates the absorption of fluid and helps to maintain body fluids. Sodium may also stimulate voluntary drinking.
10 tablespoons sugar (120 g)
3/4 teaspoon salt (4,2 g)
1 package unsweetened powdered cold drink
Water to make up to a final volume of 2 ℓ
Per cup, the drink provides:
14,8 g carbohydrates (6%)
230 kJ energy
102 mg sodium
121 mg potassium
1/2 cup orange or berry juice (125 ml)
9 tablespoons sugar (110 g or 133 ml)
3/8 teaspoon salt (2,1 g or 2,1 ml)
1 package unsweetened powdered cold drink
Water to make up to a final volume of 2 ℓ
Ingredients other than fluid, carbohydrates and electrolytes are unnecessary in sports drinks because the body cannot use them during exercise.
Drink flavoured fluids through a straw to limit the amount of contact between the sports drink and teeth. This can reduce the risk of dental decay.
10.5 How should an athlete start a competition day?
Ideally, an athlete should start a competition day rested, relaxed, refuelled, and rehydrated. Try to get a good night’s sleep to ensure that you are rested, and plan and pack your cooler box the night before so that you can relax when it comes to your competition day nutrition (see the FAQ on ‘Is the food supplied at sports events recommended for athletes?’ for cooler box ideas). To ensure that you are fully refuelled and rehydrated before your competition event, you may also need to plan when and what you will be eating for breakfast on the competition day (e.g. if you need to get up very early to travel to the competition venue, you may need to eat on the run).
If you have to travel a long distance or need to make an early start before a game, pack an on-the-run breakfast.
On-the-run breakfast options
In situations where nervousness or excitement decreases appetite, use meal replacements or flavoured milk as a liquid meal.
Never experiment with something entirely new on competition day.
10.6 Can the food at sports events be recommended for athletes?
Food available from vendors at sports events (e.g. boerewors rolls, potato chips, chip sticks, and meat pies) is not ideal for athletes on competition days, as they are often high in fat and protein. Such foods take longer to digest.
10.7 What about supplements?
Supplements are often marketed as ‘ergogenic aids’, and claim to improve strength or endurance, increase exercise efficiency, achieve a performance goal more quickly, and increase tolerance for more intense training. Dietary supplements come in a variety of forms, including tablets, capsules, liquids, powders, and bars. Many of these products contain numerous ingredients in varied combinations and amounts. Among the more common ingredients are amino acids, protein, creatine, and caffeine, but can also include herbal ingredients, stimulants, hormone precursors and many more.30
As training programmes become more demanding, the role of nutrition becomes more important to sustain good performance. A varied diet that meets the energy needs of a training athlete should provide all the essential nutrients in adequate amounts to ensure optimal adaptation to training and performance. Athletes should therefore ensure that they have a good diet before contemplating supplement use.
However, over the years a culture has developed which believes that supplements can in some way compensate for poor food choices and the increased stresses of modern life. Supplements are often used:
The benefit of most supplements is still inconclusive and often not scientifically proven. Individuals respond to and tolerate supplements differently and some can experience a placebo effect.30
There is no governing body to control or regulate the production, distribution or marketing of sports supplements in South Africa. Therefore, there is no way to ensure their safety or efficacy and products can be marketed with very little control over the claims and messages they provide – a situation of which many companies take full advantage.
According to the World Anti-Doping Agency (WADA), ‘most supplement manufacturers make claims about their products that are not backed by valid scientific research, and they rarely advise the consumer about potential adverse effects. The supplement industry is a money-making venture and athletes should get proper help to distinguish marketing strategies from reality.’
Supplements are big business. Athletes are often drawn by the images of picture-perfect bodies and the promise of enhanced performance or recovery by a certain product. Yet, there are many potential risks and little or no benefit.(31)
Many dietary supplements contain multiple ingredients. However, much of the research has focused only on single ingredients. One therefore cannot know or predict the effects and safety of single ingredients in combinations. The amounts of ingredients may vary among products and sometimes the products contain proprietary blends of ingredients without stating the amounts of each ingredient in the blend.30
Supplements can have side effects and may interact with prescription and over-the-counter medications. In some cases, the active constituents of botanical or other ingredients present are unknown. Many supplements that contain multiple ingredients have not been adequately tested in combination with one another.30 Supplements can also be contaminated by anabolic steroids and other prohibited stimulants. This means that an athlete’s use of a sports supplement may lead to a doping test turning out to be positive.32
Sports drinks are aimed at fluid and fuel delivery during exercise. In general, a sports drink that is used during exercise should contain carbohydrates (6% to 8%), sodium (20 to 30 mmol/ℓ) and potassium (3 to 5 mmol/ℓ). The recommendation for intake should consider the climate situation (cold or hot environment), the individual carbohydrate and fluid need of the athlete and the athlete’s tolerance for the drink. Sports drinks may be beneficial to athletes doing high-intensity exercise, endurance events, prolonged intermittent exercise or weight class sport for quick recovery.
Sports gels and sports or energy bars are a compact way of consuming a variety of nutrients and can be very useful to busy athletes. Solid bars are better as they provide more nutrients than energy drinks. It is important to consume these products together with adequate fluids to meet hydration needs and to reduce the risk of gastrointestinal intolerance.33
Protein and protein components
Athletes with a high protein need can use protein-rich food sources such as dairy products, meat, fish, eggs and soya. The intake of supplemental protein when the diet is already sufficient in protein will probably have no additional benefit for the athlete. There is also little supporting evidence that supplements with individual amino acids can benefit athletes who are following an adequate diet. Some athletes, however, find it difficult to consume protein food sources at the ideal time and a protein supplement may be convenient. Athletes should be aware of protein supplements that contain extra ingredients and impurities.
Amino acids are individual components of protein molecules and are sold with promises of superior functioning. However, most amino acids are found in abundance in food sources, making supplementation unnecessary and expensive.
Vitamins and minerals
Official recommendations for the vitamin and mineral intake for athletes do not exist, but it is generally accepted that athletes need more than sedentary people. These nutrients are best supplied through a varied diet based on nutrient-rich food. In athletes who restrict energy intake or when there is a limited food supply, a multivitamin-mineral supplement might be helpful. There is no justification for taking extra vitamin supplements. There is very little evidence to suggest that extra vitamins and minerals will benefit athletes who do not present with a deficiency.33
Caffeine
Caffeine is a legal and known stimulant. Athletes have used caffeine to enhance performance for decades. Known side effects are irritability, nervousness, increased heart rate, headaches, and loss of sleep. If you are not a regular caffeine user it would be wise not to start, as it can be very addictive.14
Creatine
Creatine is found naturally in skeletal muscle tissue and liberates adenosine triphosphate (ATP) for brief high-intensity exercise. The human body can make creatine from amino acids that become available after the digestion of protein. Creatine is also found in food sources, with meat and fish being the richest natural sources of creatine. As a supplement, creatine is available in powder, liquid, and capsule form. Creatine supplements have become popular among competitive athletes in an attempt to enhance energy production, increase the body’s ability to maintain force and delay fatigue. However, products containing creatine do not work by themselves; instead, they help athletes maximise their training or performance only because of the improvement in recovery time. Strength and muscle mass changes associated with creatine use, therefore, occur because athletes are able to do more work but with less fatigue in a specific period of time.
Creatine supplementation has been shown to be most beneficial in repeated bouts of high-intensity exercise, separated by short recovery intervals. However, not all studies have shown that creatine improves athletic performance or that everyone responds the same way to creatine supplements. People who tend to have naturally high stores of creatine in their muscles don’t get an energy-boosting effect from extra creatine.
At present, creatine seems relatively safe for use with minimal to no side effects if taken as directed. Failure to do so may negate its proposed benefit or even lead to decreased performance because of intestinal distress.14,32
Creatine as a supplement has been studied for short-term use only. Although creatine is not banned by the International Olympic Committee, using it for athletic performance is controversial, because:
There is concern over the marketing of creatine-containing supplements to teens since neither safety nor effectiveness in persons younger than 18 have yet been tested. The efficacy of creatine supplementation in children and adolescents is questioned for the following reasons:
Factors such as optimal training, sufficient rest and sleep, good nutrition, the right equipment and the correct mental attitude will produce much larger performance gains than any supplement. Any athlete will improve their performance by focusing on these basics, rather than relying on a ‘quick fix’ that most probably doesn’t work or has potentially adverse effects.14
Providing children with supplements creates a false sense of security and may encourage faulty eating habits. Another disadvantage of supplement use is that young athletes may erroneously associate improvements in performance with whatever supplements they may be taking. They may be less likely to attribute progress to training, hard work and a balanced diet. This type of false reinforcement may also encourage children to try other types of supplements and substances and lead to a snowball effect with undesired consequences.14
‘For the young athlete, the key to health and performance cannot be found in any one food or supplement, but in a proper combination of foods that provide many different nutrients that the body requires. Variety and moderation are the best strategies to achieve balance.’
A professionally trained dietitian can add value for athletes or players. Sports coaches can benefit from the following:
PRODUCT DEFINITION
Cereal bar: a snack made of breakfast cereal and other sticky ingredients into a chewy bar; also called a breakfast bar.
Drinking yoghurt: low-fat, flavoured and sweetened drinking yoghurt.
Energy bar: a bar-shaped snack intended to boost physical energy, typically containing a combination of carbohydrates, protein and fat, and fortified with vitamins and minerals.
Flavoured milk: low-fat, flavoured, and sweetened milk.
Maas/Amasi: full-cream soured milk, typically containing 3,66 g of fat per 100 g.
Meal replacement: formulated food that can replace one or more daily meals. It supplies the necessary macronutrients as well as vitamins and minerals of a typical meal. It comes in a powdered form that is reconstituted with either milk or water.
Nutritional supplements: concentrated sources of nutrients or other substances with nutritional or physiological effects that complement the normal diet and can be in a tablet, capsule, syrup, or powder form.
Sports drink: a flavoured and sweetened commercial drink with a typical 6%–8% carbohydrate concentration.
Sports snack bar or liquid meal supplement: specially designed convenience bar or liquid that helps an athlete address the special nutritional needs for their specific sport in situations where everyday foods are not practical to eat.
Yoghurt: low-fat, flavoured, and sweetened yoghurt.
TERMINOLOGY:
Adaptation: the changes in body systems due to the stress of exercise over a period.
Branched-chain amino acids (BCAA): three essential amino acids (leucine, isoleucine, and valine) that help form muscle tissue.
Carbohydrate-electrolyte solutions: fluids containing water, various forms of carbohydrate such as glucose and fructose, and various electrolytes such as sodium, chloride, and potassium, in a solution designed to maintain optimal hydration and energy during exercise.
Carbohydrate loading: a dietary method used by endurance-type athletes to help increase the carbohydrate (glycogen) levels in their muscles and liver.
Creatine: a nitrogen-containing compound found in the muscles, usually combined with phosphate to form phosphocreatine.
Dehydration: a reduction of the body water to below the normal level of hydration; water output exceeds water intake.
Energy availability: the energy that is available to the body after the energy cost of physical activity has been deducted from the daily energy intake.
Ergogenic aids: work-enhancing agents that are used in attempts to increase athletic or physical performance capacity.
Essential amino acids: those amino acids that must be obtained in the diet and cannot be synthesised in the body. Also known as indispensable amino acids.
Fatigue: a generalised or specific feeling of tiredness that may have a multitude of causes, either mental or physical.
Food fads: the use of dietary fads based upon theoretical principles that may or may not be valid; usually used in a negative sense, as in quackery.
Glycaemic index: a ranking system relative to the effect that consumption of 50 grams of a particular carbohydrate food has upon the blood glucose response over the course of two hours. The normal baseline is 50 g of glucose, and the resultant blood glucose response is scored at 100.
Glycogen: a polysaccharide that is the chief storage form of carbohydrate in animals; it is stored primarily in the liver and muscles.
High-quality weight loss: unwanted fat mass loss, without losing muscle mass.
Hyperhydration: the practice of increasing the body-water stores by fluid consumption prior to an athletic event; a state of increased water in the body.
Hypoglycaemia: the decline in blood glucose levels (usually below 3,5 mmol/ℓ), which can happen during prolonged or repeated bouts of high-intensity exercise when the liver glycogen store is depleted and carbohydrates are not being consumed.
Hyponatraemia: the decline in sodium levels, which can happen during prolonged exercise with excessive fluid intake and/or sodium losses.
Intermittent fasting: a dietary strategy that focuses on meal timing and consists of a combination of voluntary fasting (usually more than 12 hours) and non-fasting (re-feeding) over a given period.
Ketogenic diet: a diet that is very high in fat, adequate in protein and very low in carbohydrates (usually less than 50 g of carbohydrate per day).
Low carbohydrate availability: limited or low body carbohydrate stores (low muscle and liver glycogen levels).
Osmolality: the osmotic concentration determined by the ionic concentration of the dissolved substance per unit of solvent.
Periodisation: a technique applied to resistance training, as well as other forms of exercise training, that modifies the amount of exercise stress placed on the individual over the course of time. Various cycles, such as the microcycle, mesocycle, and macrocycle, are designed to allow the body to adapt to exercise stress in ways beneficial to performance enhancement.
Recovery: the rest intervals between exercise sessions.
Sports gels: commercial food products targeted to athletes, consisting primarily of carbohydrates in a gel form.
Time-restricted feeding: a specific intermittent fasting method that recommends fasting for 16 hours and shortening the duration of the daily eating window (during active daylight) to a maximum of eight hours, without altering energy intake or diet quality.
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