Nutrition in athletics is a very controversial topic. However, for an athlete to have confidence that his/her diet is beneficial he/she must understand the role each food component plays in the body's overall makeup. Conversely, it is important to identify and understand the nutritional demands on the physiological processes of the body that occur as a result of racing and training so that these needs can be satisfied in the athlete's diet.
For the above reasons, a basic nutrition primer should help the athlete determine the right ingredients of his/her diet which fit training and racing schedules and existing eating habits. The body requires three basic components from foods: 1) water; 2) energy; and 3) nutrients.
Water is essential for life and without a doubt the most important component in our diet. Proper hydration not only allows the body to maintain structural and biochemical integrity, but it also prevents overheating, through sensible heat loss (perspiration). Many cyclists have experienced the affects of acute fluid deficiency on a hot day, better known as heat exhaustion. Dehydration can be a long term problem, especially at altitude, but this does not seem to be a widespread problem among cyclists and is only mentioned here as a reminder(but an important one).
Energy is required for metabolic processes, growth and to support physical activity. The Food and Nutrition Board of the National Academy of Sciences has procrastinated in establishing a Recommended Daily Allowance (RDA) for energy the reasoning being that such a daily requirement could lead to overeating. A moderately active 70 kg (155 lb) man burns about 2700 kcal/day and a moderately active 58 kg (128 lb) woman burns about 2500 kcal/day.
It is estimated that cyclists burn 8-10 kcal/min or about 500-600 kcal/hr while riding (this is obviously dependent on the level of exertion). Thus a three hour training ride can add up to 1800 kcals (the public knows these as calories) to the daily energy demand of the cyclist. Nutritional studies indicate that there is no significant increase in the vitamin requirement of the athlete as a result of this energy expenditure.
In order to meet this extra demand, the cyclist must increase his/her intake of food. This may come before, during or after a ride but most likely it will be a combination of all of the above. If for some reason extra nutrients are required because of this extra energy demand, they will most likely be replenished through the increased food intake. Carbohydrates and fats are the body's energy sources and will be discussed shortly.
This is a broad term and refers to vitamins, minerals, proteins, carbohydrates, fats, fiber and a host of other substances. The body is a very complex product of evolution. It can manufacture many of the resources it needs to survive. However, vitamins, minerals and essential amino acids(the building blocks of proteins) and fatty acids cannot be manufactured, hence they must be supplied in our food to support proper health.
Vitamins and Minerals
No explanation needed here except that there are established RDA's for most vitamins and minerals and that a well balanced diet, especially when supplemented by a daily multivitamin and mineral tablet should meet all the requirements of the cyclist.
Proper electrolyte replacement (sodium and potassium salts) should be emphasized, especially during and after long, hot rides. Commercially available preparations such as Exceed, Body Fuel and Isostar help replenish electrolytes lost while riding.
Food proteins are necessary for the synthesis of the body's skeletal (muscle, skin, etc.) and biochemical (enzymes, hormones, etc.) proteins. Contrary to popular belief, proteins are not a good source of energy in fact they produce many toxic substances when they are converted to the simple sugars needed for the body's energy demand.
Americans traditionally eat enough proteins to satisfy their body's requirement. All indications are that increased levels of exercise do not cause a significant increase in the body's daily protein requirement which has been estimated to be 0.8 gm protein/kg body weight.
Carbohydrates are divided into two groups, simple and complex, and serve as one of the body's two main sources of energy.
Simple carbohydrates are better known as sugars, examples being fructose, glucose (also called dextrose), sucrose (table sugar) and lactose (milk sugar).
The complex carbohydrates include starches and pectins which are multi-linked chains of glucose. Breads and pastas are rich sources of complex carbohydrates.
The brain requires glucose for proper functioning which necessitates a carbohydrate source. The simple sugars are quite easily broken down to help satisfy energy and brain demands and for this reason they are an ideal food during racing and training. The complex sugars require a substantially longer time for breakdown into their glucose sub units and are more suited before and after riding to help meet the body's energy requirements.
Fats represent the body's other major energy source. Fats are twice as dense in calories as carbohydrates (9 kcal/gm vs 4 kcal/gm) but they are more slowly retrieved from their storage units (triglycerides) than carbohydrates (glycogen). Recent studies indicate that caffeine may help speed up the retrieval of fats which would be of benefit on long rides.
Fats are either saturated or unsaturated and most nutritional experts agree that unsaturated, plant-based varieties are healthier. Animal fats are saturated (and may contain cholesterol), while plant based fats such as corn and soybean oils are unsaturated. Unsaturated fats are necessary to supply essential fatty acids and should be included in the diet to represent about 25% of the total caloric intake. Most of this amount we don't really realize we ingest, so it is not necessary to heap on the margarine as a balanced diet provides adequate amounts.
What The Body Needs
Now that we have somewhat of an understanding of the role each food component plays in the body's processes let's relate the nutritional demands that occur during cycling in an attempt to develop an adequate diet. Basically our bodies need to function in three separate areas which require somewhat different nutritional considerations. These areas are: 1) building; 2) recovery; and 3) performance.
Building refers to increasing the body's ability to perform physiological processes, one example being the gearing up of enzyme systems necessary for protein synthesis, which results in an increase in muscle mass, oxygen transport, etc. These systems require amino acids, the building blocks of proteins. Hence, it is important to eat a diet that contains quality proteins (expressed as a balance of the essential amino acid sub units present) fish, red meat, milk and eggs being excellent sources.
As always, the RDA's for vitamins and minerals must also be met but, as with the protein requirement, they are satisfied in a well balanced diet.
This phase may overlap the building process and the nutritional requirements are complimentary. Training and racing depletes the body of its energy reserves as well as loss of electrolytes through sweat. Replacing the energy reserves is accomplished through an increased intake of complex carbohydrates (60-70% of total calories) and to a lesser extent fat (25%). Replenishing lost electrolytes is easily accomplished through the use of the commercial preparations already mentioned.
Because the performance phase (which includes both training rides and racing) spans at most 5-7 hours whereas the building and recovery phases are ongoing processes, its requirements are totally different from the other two. Good nutrition is a long term proposition meaning the effects of a vitamin or mineral deficiency take weeks to manifest themselves. This is evidenced by the fact that it took many months for scurvy to show in sailors on a vitamin C deficient diet. What this means is that during the performance phase, the primary concern is energy replacement (fighting off the dreaded "bonk") while the vitamin and mineral demands can be overlooked.
Simple sugars such a sucrose, glucose and fructose are the quickest sources of energy and in moderate quantities of about 100 gm/hr (too much can delay fluid absorption in the stomach) are helpful in providing fuel for the body and the brain. Proteins and fats are not recommended because of their slow and energy intensive digestion mechanism.
Short, one day rides or races of up to one hour in length usually require no special nutritional considerations provided the body's short term energy stores (glycogen) are not depleted which may be the case during multi-day events.
Because psychological as well as physiological factors determine performance most cyclists tend to eat and drink whatever makes them feel "good" during a ride. This is all right as long as energy considerations are being met and the stomach is not overloaded trying to digest any fatty or protein containing foods. If the vitamin and mineral requirements are being satisfied during the building and recovery phases no additional intake during the performance phase is necessary.
Basically, what all this means is that good nutrition for the cyclist is not hard to come by once we understand our body's nutrient and energy requirements. If a balanced diet meets the RDA's for protein, vitamins and minerals as well as carbohydrate and fat intake for energy then everything should be OK nutritionally. It should be remembered that the problems associated with nutrient deficiencies take a long time to occur. Because of this it is not necessary to eat "right" at every meal which explains why weekend racing junkies can be quite successful on a diet of tortilla chips and soft drinks. However, bear in mind that over time, the body's nutritional demands must be satisfied. To play it safe many cyclists take a daily multivitamin and mineral supplement tablet which has no adverse affects and something I personally recommend. Mega vitamin doses (levels five times or more of the RDA) have not been proven to be beneficial and may cause some toxicity problems.
"Good" nutrition is not black and white. As we have seen, the body's requirements are different depending on the phase it is in. While the building and recovery phases occur somewhat simultaneously the performance phase stands by itself. For this reason, some foods are beneficial during one phase but not during another. A good example is the much maligned twinkie. In the performance phase it is a very quick source of energy and quite helpful. However, during the building phase it is not necessary and could be converted to unwanted fat stores. To complicate matters, the twinkie may help replenish energy stores during the recovery phase however, complex carbohydrates are probably more beneficial. So, "one man's meat may be another man's poison."
This term refers to the quantity of nutrients in a food for its accompanying caloric (energy) value. A twinkie contains much energy but few vitamins and minerals so has a low nutrient density. Liver, on the other hand, has a moderate amount of calories but is rich in vitamins and minerals and is considered a high nutrient density food.
Basically, one must meet his/her nutrient requirements within the constraints of his/her energy demands. Persons with a low daily activity level have a low energy demand and in order to maintain their body weight must eat high nutrient density foods. As already mentioned, a cyclist has an increased energy demand but no significant increase in nutrient requirements. Because of this he/she can eat foods with a lower nutrient density than the average person. This means that a cyclist can be less choosy about the foods that are eaten provided he/she realizes his/her specific nutrient and energy requirements that must be met.
Now, the definition of that nebulous phrase, "a balanced diet". Taking into consideration all of the above, a diet emphasizing fruits and vegetables (fresh if possible), whole grain breads, pasta, cereals, milk, eggs, fish and red meat(if so desired) will satisfy long term nutritional demands. These foods need to be combined in such a way that during the building and recovery phase, about 60-70% of the total calories are coming from carbohydrate sources, 25% from fats and the remainder (about 15%) from proteins.
It is not necessary to get 100% of the RDA for all vitamins and minerals at every meal. It may be helpful to determine which nutritional requirements you wish to satisfy at each meal. Personally, I use breakfast to satisfy part of my energy requirement by eating toast and cereal. During lunch I meet some of the energy, protein and to a lesser extent vitamin and mineral requirements with such foods as yogurt, fruit, and peanut butter and jelly sandwiches. Dinner is a big meal satisfying energy, protein, vitamin and mineral requirements with salads, vegetables, pasta, meat and milk. Between meal snacking is useful to help meet the body's energy requirement.
All this gibberish may not seem to be telling you anything you couldn't figure out for yourself. The point is that "good" nutrition is not hard to achieve once one understands the reasons behind his/her dietary habits. Such habits can easily be modified to accommodate the nutritional demands of cycling without placing any strict demands on one's lifestyle.