Optimal Performance for Endurance Athletes

The Diet Controversy

Debate over what is the ideal performance enhancing diet for endurance athletes is still raging. Just how much carbs, proteins and fats should be eaten to give you a competitive edge?

Carb Mania

Many people, the scientific community included, still believe that a diet high in carbohydrates and low in fat is best for endurance athletes. Its enduring popularity is based on research that shows that if you do not have sufficient glycogen in the muscle obtained mostly through carbs in the diet, you will hit the wall.

The generally accepted dietary level of carbs for athletes is 55+ % and there seems to be little thought about the types of carbs consumed. Amongst the athletic community a carb is still a carb. Typically athletes consume 60-70% of their total food intake as carbs. And unfortunately it is common for athletes to consume donuts, cokes, cakes, biscuits, sweets and all manner of sugary and fat dense foods in the name of carbs and glycogen replacement. Natural medicine however takes a more sophisticated view on this.

Carbs are not all created equal. They are classified according to their glycemic index (GI), which is how quickly they secrete insulin in the body. A diet high in refined sugars (donuts etc) consists of high GI foods. They limit endocrinal balance, cause weight gain and mineral imbalances and are dubious as a health strategy for the general population let alone athletes!   With carbohydrate levels in excess of 60%, athletes also risk a diet of insufficient essential fatty acids and proteins.

Protein needs

Athletic interest in a diet higher in protein first started with bodybuilders and coaches as they tried to find ways of increasing muscle mass. Proteins are also important for endurance athletes. They maintain and build muscle mass, prevent weight gain by limiting insulin secretion, result in optimal power to strength ratio and ensure better endocrinal balance and improved overall health.

But the key and still contentious question shrouding protein is how much protein is enough. The answer seems to be between 1.2 to 1.4 g/kg of body weight per day (Fielding RA, Parkington J; 2002). This means that a 65 kg athlete needs between 7.8 and 9.1 grams of protein a day.

The Zone Diet

Interest in reducing the carbohydrate content of the diet was also spawned by the work of Maffetone, the father of the zone diet. The zone diet or the 30:40:30 diet prescribes 30% protein, 40% carbohydrates and 30% fats. It involves more protein, more good fats (flax seed, olive oil) and low glycemic vegetables classed as good carbohydrates. Underlying this diet prescription is the belief that real and minimally processed whole foods, will give you more energy for endurance. It represents a whole foods eating plan that addresses the endocrinal balance, weight, nutrition and therefore the health of the athlete.

Critics of the zone diet claim there is insufficient carbohydrate to ensure glycogen replacement, which will inhibit athletic performance. They prefer a 15% protein and 55% carbohydrate level. Maffetone and the zone enthusiasts argue these levels have insufficient protein to maintain lean body mass, and that too high carbohydrate levels disrupt hormones, restrict the flow of oxygen to muscles, inhibit the utilization of stored fat for energy and ultimately increase body fat.

There are no long-term trials that have tested the zone diet, largely due to the inherent difficulties in conducting long-term research on dietary regimes. In the absence of randomized control trials we must rely on anecdotal evidence. There is a significant weight of evidence through the work of Dr Phil Maffetone (“Eating for Endurance”) to suggest the zone diet works for endurance athletes when using low intensity training.

Fats Too

Interest and scientific support for higher levels of dietary fats also came from the zone diet. It is now generally accepted that the 30% fat component of the zone diet is an acceptable level rather than the low fat levels of the high carbohydrate and low fat diet (Brown, 2000). Fats at this level assist with reduction in lactate production due to lower carbohydrate burning. Research (Pendergast; 1994) has shown improved running performance over a two-month period on higher levels of fats.

The optimal diet for endurance athletes is slowly being defined. The 30% fat level should comprise good fats (olive, flax seed and fish oils) and should conform to a ratio of 2:1 olive:flax/fish. If body weight is a hindrance to athletic performance then the 30:40:30 is strongly indicated. Choice of carbohydrates should be complex and good quality carbs (cereals, fruit and vegetables). The weight of anecdotal research evidence supports the use of the zone diet for endurance athletes, specially when the exercise form is low intensity as in distance running.

All proteins are not created equal.

Having resolved the question of how much protein to have in your diet the next important question is what type of protein is best. Each of the protein types, of which we will be addressing whey, soy and rice have specific benefits and advantages to the athlete.

Whey protein concentrate improves immunity, and as the stress imposed on the body during training and competition can suppress immunity, this is a good choice. Whey protein also has the highest biological value (BV) of the three. BV is a measure of how much of the protein is actually absorbed by the body. The higher the BV the better they are at reducing muscle loss. The gold standard, and the protein that all other proteins are measured against, is the egg. Eggs have a BV of 100. The BV rating of whey is 104 or higher, depending on the quality of the whey.

Soy protein has a lower BV of 74. Soy has had some bad press because they have been found to contain something known as "anti -nutrients" (lectins and protease inhibitors) that block the digestion and absorption of many nutrients. Manufacturers of high quality soy protein isolates have addressed this problem by removing or reducing their activity during manufacture. Soy protein is a good choice for athletes who are menopausal, who don’t tolerate dairy, have high cholesterol or cardiovascular problems and who may benefit from raising thyroid hormone output. If you tolerate whey then a ratio of 2:1 whey to soy will give you the best of both worlds.

Rice protein is the least reactive of the proteins and is therefore a low allergy protein. Rice protein is a good choice for anyone prone to inflammation, allergies and gut disturbances. It has the lowest BV of the proteins with a BV of 59. If you are in this group then seek assistance from a natural medicine practitioner in improving your food tolerance and inflammation.

Hydration

Athletes become easily dehydrated and poor performance is the usual outcome. Common side effects of dehydration are heat stress, headaches, fatigue and reduced performance. Because thirst is not a good indicator of fluid loss, the best solution for ensuring hydration is to drink before, during and after training. Try following these four simple rules:

·         Practice Drinking: condition your body to tolerate fluid while exercising;

·         Monitor: how much you are drinking in clearly marked bottles;

·         Replace: your fluid loss : 1 litre for every 1kg of weight loss; replacement should occur while training and after exercising. As an accurate measure of fluid loss weigh yourself after exercise longer than 1 hour.

·         Pre-load: Prior to exercising make sure you are hydrated to the point of your urine being clear/pale.

·         Mind your minerals: Iron, magnesium, calcium, & potassium

Iron

A lot has been written about the importance of iron in the diet of athletes and for good reason. The importance of good iron status is paramount. It enables oxygen transport from the lungs to cells (hemoglobin), and to the mitochondria of the muscle (myoglobin. It helps the removal of waste and helps buffer acidosis during intense exercise. Iron status is therefore intrinsically tied to performance. Unfortunately, it is only when athletic performance starts to slip that iron status is questioned.

Two factors are worth considering with iron. Endurance athletes have a higher iron requirement than other athletes and research has shown that female endurance athletes in particular have low iron intakes.

Endurance athletes need more iron because of the intensity of their training. Gastrointestinal bleeding, the physical trauma incurred by red blood cells during high impact running and increased iron loss due to sweat loss are causes.

The most at risk groups with low dietary intake of iron are vegetarians and those on a restricted dietary intake and fad diets. It is an inescapable fact that the iron sources of meat and meat products are both higher and more easily absorbed than iron from vegetable sources. The haem source of iron in meat has an absorption rate of about 23% versus 2-8 % in vegetables. For this reason iron supplementation is recommended for vegetarian endurance athletes who are serious about their performance.

Helpful ways of improving iron absorption are:

Ensure that your food choices are iron dense; green leafy vegetables, whole grains, lentils, kelp, brewers yeast, parsley, dried prunes, peaches, pears;

·         Cook vegetables to increase the amount of iron you absorb into your bloodstream;

·         Choose whole grain cereals and those enriched with iron;

·         Optimize your absorption with vitamin C; have a fruit juice or piece of fruit prior to eating your meal.

·         Avoid drinking tea or coffee at mealtimes if vegetable iron sources are being consumed.

Magnesium

Magnesium is the true ally of athletes. It single-handedly increases lactic acid clearance, muscle strength and power output and performance. It prevents muscular aches and cramping and also has an oxygen sparing effect (Kappes et al; 1992). Since magnesium is available in a wide range of foods most athletes assume that as long as they are eating a varied and healthy diet that they have sufficient magnesium.

This next study will change your mind (Stendig-Lindberg et al 1987). Twenty highly trained athletes that took 72 hours to complete a 120km hike took three months to replenish their magnesium levels by dietary means to their pre-hike level.

The reason for the slow magnesium rebuild is that the western diet can deplete magnesium. Alcohol, coffee, high sugar use, salt, soft drinks are all depleting in magnesium, making magnesium supplements are a necessity. Furthermore it is a worthwhile strategy to pre-load magnesium before a race (1.5 g three times a day for 2-3 days) and also ensure that your sports drink contains an easily digested form (magnesium diglycinate) to avoid intestinal upsets.

Magnesium, Potassium & Calcium

Minerals work together in the body to help balance out the effect of inadequate supply of other minerals. Low levels of magnesium will cause low potassium and calcium levels as the body loses these minerals in an attempt to offset the spasm resulting effect of low magnesium levels. Most sports drinks contain potassium, calcium and sodium but it is magnesium, which is the key regulator for the electrolytes and needs supplementing.

A winning strategy

Nutritional strategies are a key element to performance. You need to consider hydration, carbohydrates, protein, fats, iron and magnesium.

If training lasts longer than 1 hour, glycogen levels will fall. There is a shift from muscle glycogen over to blood glucose. When both muscle and blood glycogen levels are low you will start to lose muscle mass and you need to replace both carbohydrate and protein.

Cape Town researchers showed that fat loading is useful for long events (longer than 3 hours) of moderate exercise intensity. Higher fat stores will preserve your glycogen stores, which means you should have less fatigue and increased capacity to push hard at the end of the race.

Preloading

Focus on your hydration and drink at least 2 litres a day of water during your taper;

Commence pre-loading magnesium three days prior; 1.5 gm three times a day;

Racing is a highly stressful event for the body and the more relaxed you are in approaching your race the better your performance will be. So do ample meditation and yoga during your taper;

Preload fats for ten days prior to your race; ensure the fats are good quality in a 2:1 ratio of olive to flax seed/fish oils; 8 tablespoons olive and 4 flax seed/fish oil per day;

Preload carbohydrates up to 5 g of carbs per kilo of body weight for the last three days prior to the race.

Pre-race:

500-600 calories of carbohydrate in a form that is easy to digest (sports drink) at least 1 hour prior to racing.

Drink the equivalent of 2 cups of water in a sports drink 2 hours prior and 1 cup of sports drink, half an hour prior.

I recommend the use of a sports beverage, which contains carbohydrate, protein and magnesium for full race preparation.

Mid race:

During exercise most people can tolerate 1/2 to 3/4 cup of sports drink each 20 minutes.

Choose either water or a quickly absorbed sports drink, or a dilute carbohydrate-containing beverage.

During ultramarathon events a beverage that contains carbohydrate, protein and electrolytes should be consumed at regular intervals.

Post race:

50-75 grams of carbohydrate for every hour of exercise up to a total of 500 g.

The protein requirement of 1.4-2.0 kg of protein per kg of body weight should be achieved by the end of day.

1 litre for every 1 kg of weight loss should be consumed.

Supplements & Improved performance

Endurance training and races are very stressful to the body. A recent study from the University of Birmingham (UK) showed that low intensity and long duration exercise resulted in the lowest levels of immune response. This means that you are more exposed than most other athletes to infection. This effect can be countered by supplementing an immune boosting complex during training and racing. But don’t self prescribe. See a natural medicine practitioner for a complex to suit your individual needs.

Antioxidant support should be included in your daily supplements. Endurance training increases your metabolism resulting in the formation of higher levels of free radicals. Free radicals can damage and age the body. To counter their effects take an antioxidant supplement that includes both vitamin (A,C,E) and enzyme (selenium) classes. A whole foods diet is also essential in providing a good dietary source of antioxidants.

Health & Winning

It seems that the plethora of writing on athlete nutrition ignores the most important ingredient in performance. That ingredient is health. The stresses imposed on you as an endurance athlete are enormous and your tolerance to that stress is ultimately dependent on your health. The greatest impacts on your health are your diet, lifestyle and your peace of mind.

We have spent time discussing diet but what about lifestyle and state of your mind.  Endurance training is a high stress zone. This should be countered within your lifestyle to lower your stress threshold. Stress lowering and non-competitive activities of yoga, meditation and Tai Chi are excellent choices.