Proper nutrition is important both on and off the bicycle. On the bicycle during a long training ride or race, it keeps fuel levels up. Off the bicycle, it refuels the body and allows it to rebuild between workouts.
This Section covers the basics of general nutrition. If you want to read in greater detail, check out any number of good nutrition books, some written specifically for endurance athletes. (We recommend Sports Nutrition for Endurance Athletes, by Monique Ryan.) You can also work with a registered dietitian to develop a nutritional program that suits your needs. Dietitians can provide in sight and advice that's hard to obtain from a book.
Almost all professional riders and teams work with a nutritionist.
NUTRIENTS
Six categories of nutrients are necessary for the human body to function: carbohydrates, fats, protein, vitamins, minerals, and water. These nutrients are responsible for every action in the body, including producing energy, building tissue, catalyzing chemical reactions, transporting oxygen and nutrients, and maintaining body temperature (thermoregulation).
Much research has gone into determining the optimal amount of each nutrient necessary to sustain and improve endurance performance. Too little or too much of any one may be detrimental to performance, so the nutritional goal of an endurance athlete is to get the right amount of each.
Carbohydrates
Carbohydrates are an extremely important fuel source for the human body. They are the only source of energy that the central nervous system can use.
(It's a shortage of carbohydrates that causes the feeling of light-headedness and disorientation when you "bonk.") Carbohydrates are converted to glycogen and stored in the liver for later use, and in the muscles for on-site energy production. (The glycogen that's stored in the liver is transformed into glucose for transport in the bloodstream; it's commonly referred to as blood sugar.) Glycogen is essential in metabolizing fat as fuel.
You want to optimize your carbohydrate in take by consuming the right type, as well as the correct amount, of carbohydrates. Fruits, grains, and vegetables are good sources of carbohydrates.
When choosing grains, select unrefined whole grains whenever possible. When grains are refined, they lose important nutrients, which makes them less beneficial. Choose complex carbohydrates (starches and dietary fibers) over simple carbohydrates (simple sugars). The glycemic index measures the ability of carbohydrates to affect blood glucose levels due to their rate of absorption into the bloodstream.
Foods that are low on the glycemic index (below 50) are slower to digest and don’t greatly affect blood sugar levels (large changes in blood glucose levels have a negative impact on the human body). Low-glycemic-index foods include pasta, beans, oatmeal (not instant), peaches, and grape fruit. Foods that are moderate on the glycemic index (50 to 70) have only a slight effect on blood glucose. Examples include cream of wheat, pine apple, pears, and whole-grain bread. Foods that are high on the glycemic index (above 70) can cause a spike in blood glucose levels. This spike causes a release of insulin beyond what is necessary (hyperinsulinemia). This spike in insulin causes a reduction in blood glucose (hypoglycemia) that can negatively affect the performance of the central nervous system. Foods high on the glycemic index include soft drinks, white bread, sports drinks, and energy gels. Foods high on the glycemic index do have a place in an athlete's nutritional strategy, however, which is discussed below.
Complex carbohydrates are usually, but not always, lower on the glycemic index than simple carbohydrates. Although many unhealthy foods fall into the high-glycemic category, not all foods with a high glycemic index are bad for you. Car rots, watermelon, and potatoes are healthy foods that have a high glycemic index.
Average individuals should consume about 50 percent of their total daily caloric intake in the form of carbohydrates. For endurance athletes, the recommended figure is 60 to 70 percent, depending on the volume of training. Endurance athletes deplete glycogen stores much more rapidly than sedentary individuals and therefore must take in larger amounts of carbohydrates to replenish those stores after every workout.
Endurance athletes should therefore stay away from low-carbohydrate diets. Some "experts" claim that endurance athletes should drop their carbohydrate intake to 40 percent of their total caloric intake and increase protein intake accordingly, but there is no substantial body of scientific evidence that even remotely supports this.
Fats
Fats (or lipids) are utilized by the body in the following ways: to assist in the production of hormones, as insulation, for carrying fat-soluble vitamins, to protect vital organs from trauma, and as an energy source. Fat stores provide a virtually unlimited supply of energy (70,000 to 80,000 kCal in most people), restricted only by the availability of glycogen. On long, low-intensity rides, fat is utilized as a main source of energy.
Fat stored in the body can be categorized as "essential" fat (the amount required to maintain normal daily functions) and "nonessential" (storage beyond that amount). Fat that you consume can be categorized based on the number of chemical bonds between the carbon atoms in the fat mol ecule. Unsaturated fats contain one or more double carbon bonds, whereas saturated fats contain no double carbon bonds. You want to limit the amount of saturated fats that you consume and keep the majority of your fat intake as unsaturated fats. This will help keep down your bad cholesterol (LDL, or low-density lipoproteins). Canola, sunflower, safflower, and olive oils are high in unsaturated fats.
Butter, lard, shortening, and coconut oil are high in saturated fats and should be avoided.
Trans-fatty acids, or trans fats, don’t occur naturally but are created when food processors add hydrogen to oils, through the process of hydrogenation, to increase the shelf life of products and keep oils from separating. This greatly increases the saturation of the fat, making trans fats among the unhealthiest of nutrients. Pack aged foods must currently list all trans fats on the label, and there is a move toward eliminating all trans fat from foods.
Staying away from foods high in saturated and trans fats is more a life-and-death issue than a matter of Cycling performance. There is a strong link between diets high in saturated and trans fats and cardiovascular disease. Both types of fat in crease the amount of low-density lipoproteins in the blood. This is the "bad" cholesterol that leaves plaque deposits on artery walls.
The attraction of fats is that they make food taste better, which is probably why the diet of the average American includes much more fat than necessary. About 20 to 25 percent of an endurance athlete's caloric intake should consist of fats, and these should be mainly unsaturated. Meat, fish, and healthy oils are good sources of fat in an athlete's diet.
Proteins
Proteins are used primarily for building muscle tissue and other components in the body. Although proteins can be broken down for energy, the body does not store excess protein, so if you're using protein as your main energy source, you have placed your body in a "starvation" situation and are breaking down tissue (primarily muscle) in order to form glycogen for energy.
Proteins are made of amino acids, of which there are twenty in the body. Eight of these amino acids are considered essential in adults (ten in children). This does not mean that the remaining, non essential amino acids are not important; rather, the nonessential amino acids can be produced by the body. The essential ones, therefore, are an essential part of your diet. A complete protein is one that contains all the essential amino acids, of which animal foods such as lean meat, eggs, and milk are good sources. Vegetarians need to monitor their diets carefully to ensure that they consume sufficient quantities of essential amino acids.
When we hear about the importance of protein in an athlete's diet, it is usually in reference to power sports such as power lifting, bodybuilding, or American football. But proteins are extremely important to the endurance athlete as well. Long, high-intensity training sessions and races place a major strain on the body, and protein is essential in repairing the damage. Therefore, the dietary reference intake (DRI) recommendation of 0.8 gram of protein per kilogram of body weight may not be adequate for most endurance athletes. Most research suggests that endurance athletes need about 75 percent more, or about 1.4 grams of protein per kilogram of body weight daily. This should account for about 15 percent of your daily caloric intake, with some give or take based on the intensity and duration of exercise.
Most Americans receive more than the recommended amount of protein in their diets. The body can’t store protein for later use; excess is excreted or stored as fat. Taking in overly large quantities of protein can place unnecessary strain on the liver and kidneys.
Vitamins
Vitamins don’t provide energy directly, but niacin, B vitamins, and pantothenic acid play key roles in the chemical processes that produce ATP (adenosine triphosphate), which is the only sub stance that can be used as energy in the body.
Vitamin D is important for maintaining bone density.
Vitamin C plays an important role in the synthesis of collagen (connective tissue) and in iron absorption. Vitamin E acts as an antioxidant. These are just a few of the reasons why vitamins are essential for athletic performance.
Adequate vitamin intake can be obtained through a well-balanced diet. Individuals on insufficient diets may not receive adequate amounts of all vitamins and may need to take supplements.
Because of the increased demands on the body due to exercise, endurance athletes may need to supplement as well. Keep in mind that insufficient amounts of specific vitamins can be detrimental to development and health, and that too much of certain vitamins can be toxic. To determine the amount of each vitamin needed, consult the published list of dietary reference intake (see Appendix). Antioxidants Free radicals are unstable molecules that are missing an electron. They are formed through the body's interaction with the environment and through its normal oxidative metabolic processes.
Free radicals "steal" electrons from other molecules to stabilize. When this occurs, the other molecules are damaged or destroyed. Free radicals are linked to tissue degeneration and the development of coronary artery disease. Because metabolism increases with exercise, free-radical production also increases.
Antioxidants play an important role in pre venting free radicals from damaging the body, so it's important to consume adequate amounts.
Antioxidants fight damage caused by free radicals by donating electrons to the unstable free radical and by repairing damage caused by the free radical. Three of the most important antioxidants are the vitamins C, E, and ß-carotene (hereafter called beta-carotene). Fruits and vegetables are ideal sources of antioxidants; if you're eating a well-balanced diet, you should be getting enough antioxidants to handle free radicals.
Minerals
Nutritionally speaking, minerals are inorganic sub stances required for numerous chemical processes in the body. Some minerals, such as calcium, are needed in large quantities, whereas others, including zinc, are required only in small amounts.
Minerals are obtained through eating meats, dairy products, and plants. Three of the most important minerals-calcium, iron, and phosphorus-are discussed below.
Calcium
Calcium, by far the most abundant mineral in the human body, plays a key role in many of its chemical processes. Calcium is essential in building and maintaining healthy bones, which are 60 to 70 percent calcium. Throughout life we continually re-sorb old bone and construct new bone. Calcium deficiency can lead to low bone density, and prolonged deficiency leads to osteoporosis, in which the bones become brittle and susceptible to fractures. (Osteoporosis is discussed further in Section 15.) Calcium also plays an important role in muscle contraction.
Calcium can be obtained from dairy products and some plants, but few diets meet the minimum requirement of about 1,000 mg per day--the equivalent of 30 to 40 oz. of milk. You need to examine your diet and possibly consult a registered dietitian to ensure that you are taking in enough calcium.
If you're not getting enough calcium through your diet, you may want to consider supplementing, even though your body has more difficulty absorbing calcium from supplements in comparison to natural sources. Women are more susceptible to osteoporosis than men and need to be extremely vigilant.
Iron
Although essential, iron is required by the body only in small amounts. The majority of iron is used to make hemoglobin and myoglobin; the remainder is stored for later use. In order for oxygen to be transported in the blood, it must bind to the iron located on hemoglobin. A common sign of iron deficiency (also known as iron-deficiency anemia) is a feeling of constant fatigue, which severely limits your ability to function on a day-to-day basis, much less train or race.
Meat, particularly red meat, is the largest source of dietary iron. Liver is the richest source be cause the liver is where iron is stored in the body.
Nonetheless, it's better to eat lean meats to avoid excessive cholesterol intake. Iron can also be obtained from some plants, such as potatoes and beans, but absorption from these sources is limited.
Three categories of people are at high risk of developing iron deficiencies. Women are at risk due to blood loss during the menstrual cycle, coupled with frequently inadequate dietary intake of iron in their diets. Athletes are at risk due to iron loss through sweat and because of the increased turnover rate of hemoglobin and increased hemoglobin production that occur due to training.
Vegetarians are at risk because plant foods in general are not high in iron, and even the iron that is contained in some plant foods is not absorbed well. Anyone reading this guide is presumably an athlete, so if you are in one of these three high-risk categories, you need to be concerned with iron intake (and particularly so if you're a female vegetarian athlete). Be careful if you choose to take supplements because high levels of iron can be toxic. If you think you suffer from iron-deficiency anemia, consult your doctor, who will advise you on whether and how much to supplement.
Phosphorus Calcium binds with phosphorus to make calcium phosphate, an essential component in bones.
Phosphorus also plays an important role in energy production by assisting in the formation of ATP, ADP, and PCr. Phosphorus can be obtained from meats, dairy products, and cereals and is provided in more than adequate amounts by the average diet.
Fluids
Because our body consists of 60 to 70 percent water, it is vital to existence. About 75 percent of the weight of muscles is water. Water acts as a transport medium for gases, nutrients, and other compounds. Water is also vital in thermoregulation, cooling the body by providing fluid for sweat and absorbing heat in the body's core and moving it to the skin, where it can be cooled through the evaporation of sweat. Water does not compress and therefore helps provides structure to cells in the body.
Water is lost from the body mainly through respiration, urination, defecation, and sweating.
Exercise increases losses due to respiration and sweating, and inadequate hydration can negatively affect health and performance. When training in hot conditions, it becomes even more imperative to monitor water loss and intake.
NUTRITION AND EXERCISE
To perform optimally and stay healthy through out the season, it's important to develop a dietary strategy that covers nutrition before, during, and after training.
Individuals' reactions to type, quantity, and timing of fueling are highly variable, so no single program suits everyone. For example, "normal" insulin levels vary from individual to individual and affect the storage and transport of carbohydrates; rates of digestion vary, so the timing of intake must vary; and some individuals' sweat contains higher levels of sodium, so they need to ingest more salt. Because a proscriptive approach isn't feasible, here are some general guidelines that will help you develop a dietary strategy to meet your specific needs.
Before Training and Events
Make sure you are well hydrated before training or racing. Monitor your weight to ensure that you're replacing water lost during exercise. You don’t want to start a road trip with your radiator half empty.
Through trial and error you will determine how much and how soon to eat before a ride. If you're planning an easy ride, you probably need not be overly concerned with amounts and timing.
However, it wouldn't be wise to go to your favorite all-you-can-eat buffet and jump on the bicycle five minutes later.
Harder days require more planning. Through the process of auto-regulation (see Section 10), blood is directed where it's needed most-to working muscles and skin during exercise, and to the digestive organs after eating. If you eat too soon before exercising, your working muscles and digestive system will compete for blood flow, and this will decrease your ability to perform and may lead to gastrointestinal distress.
Some athletes can’t function without a "healthy" breakfast. To make sure this does not interfere with competition, these individuals need to get up early in order to have 2 to 4 hours in which to digest the meal. Other individuals are better served by eating a small meal 1½ to 2 hours before the race starts. Find out by trial and error during training so you know how your digestive system normally functions and thus avoid an upset stomach during an event.
Stay away from meats just before competing because they take a long time to digest. Eat carbohydrates that are low on the glycemic index, such as slow-cooked oatmeal, and avoid high-fat, heavy foods such as bacon-egg-and-cheese croissants.
Many cyclists eat an energy gel just prior to a long event to reduce the rate of glycogen depletion. This is a good idea as long as you time it correctly. Energy gels are high on the glycemic index and lead to low blood sugar levels and fatigue if they're taken 15 to 30 minutes prior to exercise.
Instead take the gel 5 minutes before starting to exercise. This will help keep blood glucose levels up, spare glycogen stored in the liver for later use, and not have a negative effect.
During Training and Events
On rides longer than 1½ to 2 hours, it's important to reduce the rate of glycogen loss. I use the phrase "reduce the rate of glycogen loss" for a reason. When you ingest glycogen during strenuous exercise, it does not go to the liver for storage, so you are not replenishing glycogen stores. Instead you're increasing blood glucose levels. The glycogen is taken up by the working muscle, thus sparing glycogen stored in the liver.
Research has demonstrated that ingesting carbohydrates during endurance activities increases performance by delaying the onset of fatigue. This is where carbohydrates that are high on the glycemic index become important. Because of the immediate energy demands while cycling, ingesting carbohydrates during the activity avoids the cascade effect-normally associated with high-glycemic carbohydrates-that leads to low blood sugar. Make sure you have enough gas in the tank when you sprint for the finish line. If your glycogen supplies fall short, so will your race.
Cyclists should ingest 30 to 60 grams of carbohydrates per hour during rides lasting longer than two hours. This recommendation depends on three factors:
__Intensity. At low-intensity workouts (less than 60 percent of VO2 max), supplementing carbohydrates is usually not necessary due to the low percentage of glycogen and the high percentage of fat being used for energy.
At moderate intensities, 30 grams per hour is sufficient, and at high intensities you will need up to 60 grams per hour.
__Distance. Longer races require much larger amounts of glycogen.
__Body size and muscle mass.
The larger the body and the greater the muscle mass, the more glycogen will be required.
In general, sports drinks and gels work better than energy bars and "normal" food during high-intensity activities. They are easier to digest and they enter the bloodstream faster. At lower intensities, solid foods work just as well. Typical sports gels contain about 25 grams of carbohydrate; sports bars contain about 45 grams; and a 12-ounce sports drink contains 60 to 80 grams. If you use energy gels, take one every 40 to 60 minutes, depending on intensity and duration.
Never try a new food strategy during a race. If energy bars, gels, or drinks will be offered on the course, find out the brand and flavors in advance and try them in training to determine how your body reacts.
Most individuals ride centuries at moderate to low intensities, finishing in five to seven hours.
That's a long time to go without "real" food. If gels do not keep hunger at bay, you may need to eat some fruit or a sandwich.
It is imperative to stay well hydrated during an event, drinking 15 to 35 ounces of water for every hour ridden, and not waiting until you feel thirsty. The distance of the event and the environ mental conditions (heat and humidity) will affect the amount of water you lose. Keep in mind that you sweat the same amount in a hot, dry environment as in a hot, humid environment, although it may seem quite different due to the rate of evaporation.
Thirst is a defense mechanism reminding us that we need to drink when hydration levels are low. Note the present tense: when hydration levels are low. Cycling is a relatively steady-state exercise with a long duration, placing a large amount of stress on the circulatory and cooling systems.
When you start feeling thirsty, it's already too late and you're on a downward spiral. When water loss equals 2 to 3 percent of body weight, the plasma volume is reduced enough to negatively impact performance. Your health will begin to be affected at a water loss of about 5 percent of body weight. At a loss in excess of 8 percent, plasma volume has dropped so low as to impair the body's ability to cool itself, leading to serious health implications including heat stress and/or heatstroke (see Section 5).
Water is sufficient for your fluid needs on rides less than two hours and on days that are not excessively hot. On longer rides or extremely hot days, you should use sports drinks as well. These will replace sodium lost in sweat and help support glycogen stores.
As bad as dehydration is, over-hydration, or hyponatremia, is also dangerous. It usually occurs during rides of 70 miles or longer, where individuals are worried about becoming dehydrated.
A combination of three factors usually leads to hyponatremia:
__The athlete drinks more water than is lost.
__There is a decrease in sodium levels through sweat. (The athlete may have insufficient sodium levels to begin with due to poor diet.)
__During exercise, auto-regulation leads to decreased renal blood flow, resulting in a decrease in urine production and an increase in water retention.
----Sports gels consumed during exercise can help limit glycogen depletion.
The imbalance created by a high concentration of water and a low concentration of sodium can cause headache, nausea, cramping, seizures, coma, heart attack, and death. Unfortunately, many of these symptoms also apply to dehydration.
Many times, hyponatremic athletes think they are dehydrated, causing them to increase their water intake, which makes the situation worse.
After Training and Events
Nutrition is an essential component of recovery. After a hard day in the saddle, you need to replenish glycogen stores in the muscles and liver. After a moderate- to high-intensity workout lasting longer than two hours, it will take about twenty-four hours to fully replenish glycogen stores with proper nutrition. You have a small window of opportunity, occurring within the first two hours post exercise, to maximize your recovery potential. For optimal results you should attempt to replenish within the first thirty minutes. Most athletes don’t refuel properly and thus enter their next training bout with low glycogen stores.
For quick absorption, replenish with foods that are high on the glycemic index. Add protein to your recovery meal to aid in muscle recuperation. Also, it is theorized that because protein influences insulin levels, it will assist in glucose and amino acid uptake into the muscle. A 4:1 ratio of carbohydrate to protein (4 grams of carbohydrates for every gram of protein) is recommended.
For some people, eating a meal of solid food during the first two hours after a hard workout can cause gastrointestinal distress, and at times it may be simply inconvenient. "Recovery drinks" are available with the correct 4:1 ratio of carbohydrates and protein. Beyond the two-hour window, continue replenishing glycogen stores by consuming carbohydrates that are low on the glycemic index to prepare for the following day's workout.
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Recovery drinks containing a 4:1 ratio of carbohydrates and
protein can increase recovery after an intense workout.
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