Frequently Asked Questions


Periodised nutrition and nutritional training

1. What is periodised nutrition or nutritional training? I’ve also heard athletes talk about “training low and competing high’- what is this?

Before embarking on any nutritional strategy during training, one needs to determine the goal of the specific training session or training season. The primary goal of a training diet is to provide nutritional support for an athlete to stay healthy and injury free while helping the body to adapt and improve fuel usage for peak performance during races. Nutrition periodization is used to describe changes in nutritional intake in response to certain periods of training. For example, during certain periods of training there is a focus on weight management and lower energy intake, whereas during other periods there is a focus on recovery and performance and higher carbohydrate intake.

As we learn more about how the body responds to training, it is becoming increasingly clear that in some instances one might get better results during races if one is not fully fuelled during certain periods of training.This can mean either training while fasting or low carbohydrate intake in and around certain training sessions. 

Training low, competing high

“Training low, competing high”, refers to an acute pattern of dietary periodization during which an athlete follows a short-term high-fat, low carbohydrate diet for 1 to 3 weeks while training, and reintroduces carbohydrates after this period. During these sessions the goal is for the body to adapt to using fuel better, and not to perform at one’s best. Carbohydrates are then re-introduced before a race (‘competing high’).In some instances, you might need to perform at your best during certain training sessions and will then have to use a nutrition strategy that provides fuel before, during and after training (as you would during races) for optimal performance and recovery.

For these strategies to be effective it needs to be well planned and individualised and a dietitian with a special interest on sports nutrition will be able to provide a personalised plan based on your unique training and nutritional needs.

TAKE HOME MESSGE: Periodised nutrition refers to changes in nutritional intake during different cycles of training and races to help the body to improve adaptations to enhance performance.

Sports drinks?

2. Should I be taking sports drinks and gels during races, or just water and food?

There are a few factors that will help you perform at your best during a race, like refuelling glycogen stores, preventing dehydration, replacing lost electrolytes and preventing stomach discomfort/upset. What you eat and drink during a race should help you achieve these goals. For some athletes this can be achieved by food and water alone, while others will need specifically formulated sports foods. Various factors will determine whether these foods are useful such as the intensity and duration of the race, how easy it is to access food vs a sports drink or food during a race, appetite and individual response to food vs sports foods. During a shorter, technical mountain bike race, it might be easier to have a sports drink in a hydration pack because of little time and ability to eat whole food, while a runner might find a sports gel helpful to use towards the end of a race as it is compact to carry and easy to consume. For longer multi stage races with varying intensity, whole food will play a more important role because it provides nutritional support for the duration of the race. It is also important to remember that fluids consumed during races also replace electrolytes lost while sweating and this should be replaced by fluid and food. Adding electrolytes to water, using specifically formulated sports drinks and foods or eating salty food will assist with adding back these salts.

TAKE HOME MESSAGE:The need for special sports foods and drinks will depend on the type of sport, intensity, duration, environment and how well food and fluids are tolerated.

Stomach cramps and nausea during races

3. I struggle to eat enough during a race and often get stomach cramps or feel nauseous. Why does this happen and what can I do to prevent it?

During strenuous long lasting exercise, blood gets directed to skeletal muscle, the lungs, heart and brain, and shunted away from the gastrointestinal tract. This can lead to nausea, stomach and intestinal cramps, vomiting or diarrhea when taking food or fluids during exercise.

Ways to prevent this is to choose foods that are easy to digest (such as simple carbohydrate rich foods that are low in fat and fibre) and trying your nutrition strategy during training sessions so that the body can get used to the food and fluids used during exercise. Highly concentrated carbohydrate rich foods and fluids such as over concentrated sports drinks or gels can lead to these symptoms and should be avoided. Foods and drinks that contain caffeine can also lead to stomach cramps and diarrhea in sensitive athletes.

TAKE HOME MESSAGE: Test any nutrition strategy before a race to determine what works and are tolerated best.

Muscle cramps while exercising

4. I often have muscle cramps (legs) while exercising. Is this food related?

Skeletal muscle (large muscles in the limbs) typically cramp because of fatigue and an under-trained muscle will cramp easily. Muscle cramps can also be due to the body’s loss of water and electrolyte imbalances. In hot conditions, athletes that sweat a lot are at greater risk for cramping. Ways to avoid muscle cramps during training and racing include being well prepared for a race (training), consuming the right amount of fluids to prevent dehydration, having salty foods or sports foods and drinks that contain electrolytes, and acclimatising to the environment you will be competing in. Muscle cramps when at rest can be due to poor blood circulation, not stretching enough after exercise, magnesium or potassium deficiency or a side effect from medication. Speak to your doctor if muscle cramps occur frequently at rest.

HIgh fat, low carb diet for endurance athletes?

5. Should endurance athletes follow a high fat ketogenic diet? OR what about high fat low carbohydrate diets for endurance athletes?

Endurance athletes can develop the ability to use fat as a fuel as an adaptation to their training. In recent years there has been an interest in strategies to further up-regulate the use of fat as fuel for exercise. Ketogenic diets are a variant of high-fat diets and have increased in popularity in recent years. Nearly all ketogenic diets obtain at least 70 - 80% of their daily kilojoules (calories) from fat, contain moderate amounts of protein (20 - 25 %) and very little carbohydrate (10 - 40 g per day).  This diet leads to a greater reliance on ketones as fuel. While physiological changes may take place and the body can adapt to using ketones as fuel, the verdict is still out as to whether it leads to enhanced performance. For example, a study of well trained endurance athletes by Cox et al. demonstrated that a ketogenic diet can improve exercise endurance and performance, while a study in Olympic-calibre race walkers failed to show an increase in performance. Other studies have shown that well trained fat adapted ultra endurance athletes can benefit from this nutritional strategy. Available evidence are limited and mixed, and more research needs to be done before appropriate recommendations can be made towards the use of high fat diets for athletic performance. If you wish to follow a ketogenic diet, contact a dietitian with a special interest in sports nutrition that will be able to provide a personalised plan based on your unique training and nutritional needs.

6. Is a vegetarian diet suitable for athletes?

Athletes may choose a vegetarian diet for various reasons from religious, moral/ethical to health reasons. Vegetarians either include dairy products (called lacto-vegetarians), eggs (ovo-vegetarians) or both ( lacto-ovo vegetarians). Vegans follow a plant based diet that exclude all animal products or by products from their diet such as meat (including chicken, fish, shellfish, insects), dairy products, eggs and honey, and seeks to exclude, as far as is possible and practical, all forms of exploitation of, and cruelty to, animals.

Nutrient dense vegetarian diets contain whole grains, legumes& pulses, nuts, seeds, vegetables and fruits. Depending on the type of vegetarian diet one follows, nutrient concerns for the athlete will include low energy, protein, iron, zinc, vitamin B12, calcium and omega 3 intake.

A well planned vegetarian diet can support sports performance, but research is lacking regarding the influence on athletic performance from long-term vegetarianism among athletes. Vegetarian athletes may benefit from seeing a professional to do a comprehensive nutritional assessment and provide guidance to prevent nutrient deficiencies and hampered performance.


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