Nutrition for Sports and Exercise Performance

I am constantly asked about sports nutrition and what is best etc, etc and I find the majority of people are not doing what is best for their situation often. Below is an article by a well known naturopath, Leslie Bailey that covers much of what is often asked. Have a read through and enjoy!

By Lesley Bailey BSc DipEd ND

An athlete can participate in strength or endurance sport at an elite or recreational level. There is a difference between the dietary needs of the occasional athlete and the serious competitor who trains daily. One obvious difference is that the training athlete needs huge amounts of food compared to the average person.

Athletes need to consider several factors in determining a diet that will help them in reaching optimal health and peak performance. These include:

• Energy needs
• Macronutrient and micronutrient needs
• Fluid requirements
• Timing of intake
• Optimal weight range and body composition
• Special nutrient needs for specific training routines
• Supplement choices.

Performance and recovery from exercise are directly associated with optimal nutrition. All athletes should eat a varied and well-balanced, nutrient dense diet to ensure optimal health. A poor diet guarantees substandard performance. An elite athlete should consult with a qualified nutrition expert for advice concerning their individual dietary needs in relation to their designated sport.

Energy Requirements for Increased Exercise

The body is fuelled by the breakdown of the energy rich compound, adenosine triphosphate (ATP). The energy produced by the breakdown of this molecule is transferred to contractile filaments in the muscle preceding contraction. The production of ATP within muscle cells occurs through two pathways:

• Oxygen dependent (aerobic) – for moderate to low intensity exercise such as walking
• Non-oxygen dependent (anaerobic) – for high intensity, short duration exercise such as sprints.

Moderate intensity sports such as jogging, hiking and gymnastics obtain approximately half the energy requirements from the aerobic pathway and the other half from the anaerobic pathway.

Carbohydrates, fats and proteins are all possible food sources of fuel for muscle contraction. Low to moderate intensity exercise with a longer duration derives energy mainly from fatty acids. Fats can supply up to 60-70% of energy needs for an ultra-endurance event. When the duration is limited and the exercise intensity is high the main energy source is derived from carbohydrates. A high fat, low carbohydrate diet leads to low glycogen stores and limits the athletes’ ability to perform high intensity exercise. Protein is only used as a fuel source if there are insufficient carbohydrates. Hence a high carbohydrate diet plays an important role in sparing muscle protein.

Inadequate energy intake compared to energy expenditure decreases athletic performance. It may cause weight losses and less muscle resulting in loss of strength and endurance. Possible compromises in female reproductive function and bone health may also occur. All athletes should consume adequate energy to maintain their optimal weight and body composition as too little body fat can also result in a poor sporting performance².

Furthermore, long term low energy intake often results in poor nutrient intake especially of the micronutrients². The average person uses only 2000-2500 kcal per day. Energy intakes can range from 3000-5000 kcal per day for male endurance athletes.

Energy requirements for an athlete depends on their height, weight, age, gender and the type, frequency, intensity and duration of their training. The athlete should ideally consume macronutrients in the following proportions:

• 60-70% of total daily kcal from carbohydrates
• 10-15% from protein and
• 20-30% from fat.

These ratios are not vastly different from the guidelines recommended to the average person; 55-58% of energy from carbohydrate, 12-15% of energy from protein and 25-30% of energy from fat.

A Diet for Training

Although what is eaten immediately or shortly before and after an event is important, it is actually the training diet that holds the most potential to influence sports performance.

While the focus and specific details will differ between athletes there are some common dietary practices that should benefit all individual athletes:

• Include a variety of foods, emphasizing foods in season and trying different variations of the same group e.g. multigrain bread, rye bread, pita bread
• Reduce certain fats and oils especially from processed foods such as biscuits and pastries and fried and battered foods
• Increase carbohydrate foods especially fresh fruits, yoghurts, whole grain breads and pasta, whole grain rice and rice cakes, starchy vegetables and legumes
• Replace fluid losses during and after training
• Moderate alcohol consumption
• Spread food intake over 5-6 smaller meals.

A high carbohydrate training diet is important for optimal sports performance because it creates larger stores of muscle glycogen thereby increasing endurance. The bigger the glycogen stores the longer the body can exercise before fatigue sets in. Heavy training may require as much as 500-800g of carbohydrate per day to help prevent carbohydrate depletion compared to the average person who would consume about 240g of carbohydrates per day.

Proteins are needed to repair exercised-induced micro damage to muscles and to support gains in lean tissue mass. Protein needs are slightly increased for resistance and strength athletes compared to endurance athletes. High protein diets compromise an athlete’s carbohydrate status and hence affect peak performance. High protein diets can lead to diuresis, potential dehydration and possibly a disruption to calcium balance leading to the excretion of high levels of calcium in the urine (hypercalciuric effect).

Fats are important for athletes as it provides energy, fat soluble vitamins and essential fatty acids. Fat is the most concentrated source of food energy supplying more than double the energy of the same weight of carbohydrates or proteins. Excessive intake of fat has been associated with illnesses such as cardiovascular disease and obesity and severe fat restriction (<15% of energy intake) can limit performance by hindering intramuscular triglyceride storage, which provides a proportion of energy for all intensities of exercise.

The vegetarian athlete may be at risk for low intake of proteins and some micronutrients due to restrictions on dairy products and meat. Nutrients that may be at risk include the vitamins B12, riboflavin and D and the minerals iron, zinc and calcium. Vegetarian athletes need to pay particular attention to their protein choices and the amounts eaten. They should consider increasing their protein intake by 10% to make up for the fact that plant proteins are not as well digested as animal proteins.

Hydration

Sports performance is impaired when athletes become progressively dehydrated. Proper hydration during training and competition enhances performance, helps maintain body temperature and plasma volume, delays fatigue and helps prevent problems associated with dehydration and sweat loss such as heat exhaustion or heat stoke^.  Sweat rates vary depending on the athlete but can exceed 1800ml/hour. Sweating causes a loss of water, iron, calcium and electrolytes, particularly sodium and to a lesser extent potassium.

Guideline for proper hydration:

• Athletes need to be well hydrated before exercise. This can be achieved by drinking generous amounts of fluid in the 24 hours before an exercise session
• Athletes should drink 400-600ml of fluid 2-3 hour before exercise to optimize hydration and allow excess to be excreted via the urine before exercise begins
• When exercising for longer than 1 hour an athlete should consume fluids containing carbohydrates and electrolytes (4-8%) rather than water alone. There is no need to replace electrolytes during a single exercise session of moderate duration especially if sodium was present in the last meal
• Drinking 100-200ml every 10-15 minutes during exercise helps the athlete remain hydrated
• Fluid temperature should be cool as chilled fluids leave the stomach more quickly than warm ones and can help reduce body temperatures.

Pre Event Considerations

Eating a pre event carbohydrate meal gives the athlete a better chance of maintaining normal blood glucose levels and enhancing performance. In strenuous events of longer than 90 minutes duration, the athlete can consider low glycaemic index (GI) foods which supply a slow release of glucose to the blood stream for increased endurance and to prolong the time before exhaustion sets in. It is important to avoid food that causes the athlete to experience abdominal cramping or flatulence. There are plenty of low fibre, low GI choices such as certain pastas and noodles which are less likely to produce abdominal discomfort (for specific food product details see http://www.glycemicindex.com). The pre event snacks should be low in fat to promote gastric emptying. The athlete should experiment with pre event meal choices and the timing during training to determine their personal preferences which can then be implemented for the event.

Some pre event eating ideas

• Cereal/porridge with low fat milk and fresh fruit
• Fruit smoothie
• Fresh fruit salad with low fat yoghurt
• Baked beans or bean alternative with toast
• Spaghetti with a low-fat tomato based sauce.

Post Event Considerations

After an event or training session glycogen stores need to be replaced as soon as possible. Consumption of high GI food such as potatoes, rice (e.g. Calrose or Jasmine) and bread replenishes muscle glycogen stores rapidly. Eating carbohydrates with a high GI rating results in higher muscle glycogen levels 24 hours after exercise as compared with the same amount of low GI carbohydrates2. The athlete should aim to ingest 1g of carbohydrate per kg of body weight within 2 hours after an event with a total of 10g of carbohydrate per kg over the 24 hours following prolonged exercise. Including protein post event helps to provide amino acids for muscle repair.

Some post event eating ideas

• Selected carbohydrate containing sports drinks
• Baked potato with baked beans
• Raisin bread with ricotta cheese and honey
• Steamed rice and stir fried vegetables
• Meat and salad roll and fresh fruit.