Nutrition and Hydration
This chapter looks at two critical but often misunderstood factors in marathon preparation and racing—nutrition and hydration. Why are these matters critical? Because two of the factors that typically conspire to make you slow in the last few miles of the marathon are glycogen depletion and dehydration. By understanding the role of nutrition for marathon preparation and racing, you can develop strategies to optimize your marathon performance.
This chapter discusses the impact of hydration on performance and how to prevent excessive dehydration, the roles of carbohydrate and fat as the primary fuels for endurance exercise and how to prevent glycogen depletion, the role of protein for endurance athletes, the need to maintain normal iron levels, and other nutrition considerations for racing the marathon. Understanding the information in this chapter is an essential component of your marathon preparation.
THE ROLE OF HYDRATION
Staying well hydrated is vital to successful marathoning during training and racing. Becoming excessively dehydrated negatively affects running performance and also slows your ability to recover for the next workout. Your blood and other fluids help remove waste products and bring nutrients to tissues for repair. Replacing lost fluids after running, therefore, will speed your recovery.
Let’s take a look at the physiology of dehydration. When you sweat, the following chain of events occurs:
Your blood volume decreases, so
less blood returns to your heart; therefore,
the amount of blood your heart pumps with each beat decreases; and eventually
as you continue to sweat, less oxygen-rich blood reaches your working muscles; therefore, you produce less energy aerobically and must run at a slower pace.
These effects are magnified on a hot day because one of your body’s major responses to hot weather is to increase cooling by sending more blood to the skin to remove heat from the body; this process means that even less blood returns to the heart to be pumped to the working muscles. The result is a higher heart rate for a given pace and an inability to maintain the same pace as on a cool day. Looked at in another way, dehydration also reduces your body’s ability to maintain your core temperature because less blood is available to be sent to your skin, and your sweat rate decreases. Struggling to maintain a fast pace on a hot day becomes more dangerous as you become progressively more dehydrated and can lead to heat exhaustion.
The main benefit of drinking during the marathon is to reduce dehydration to a moderate level so running performance is not compromised. Staying well hydrated is also important during training. The amount of dehydration that starts to affect running performance varies
between individuals and depends on a variety of factors. The American College of Sports Medicine recommends preventing dehydration of more than 2 percent of body weight (Thomas, Erdman, and Burke 2016). Your body’s thirst mechanism will lead you to drink enough most of the time. During a heavy training load in hot conditions, however, it can be useful to have a plan to ensure your hydration level is normal before running, to take in fluids during running when you are likely to lose more than 2 percent of body weight, and to rehydrate appropriately after running.
Marathoners training in hot conditions sometimes become moderately dehydrated for a few days without realizing it, which can reduce training performance and increase perceived exertion (i.e., running at a given pace feels harder). For example, if your training schedule calls for a tempo run on Tuesday and a medium-long run on Wednesday, and you are training in hot or hot and humid conditions, it can be helpful to emphasize rehydration after your tempo run to ensure you are normally hydrated for the start of Wednesday’s medium-long run. Similarly, anyone training twice per day, particularly in warm conditions, should put some thought into rehydrating prior to their second run of the day. Interestingly, paying attention to your hydration level is also useful in the winter, when the need to offset sweat loss isn’t as obvious.
Sweat rates vary considerably between runners and depend on the environmental conditions, how intensely you are running, how acclimatized you are to the conditions, and your genetic predisposition to sweating. It’s not unusual to lose 3 to 4 pounds (1.4-1.8 kg) of water per hour when running on a warm day. At this rate, during a 2-hour run you would lose about 6 to 8 pounds (2.7-3.6 kg). For a 140-pound (64 kg) runner, this represents a loss in body weight of over 4 to almost 6 percent and a likely decrement in performance of several percent. The effect increases as the run progresses, so this runner wouldn’t be any slower the first few miles but would likely find that maintaining pace becomes harder and would slow progressively later in the run. Avoiding dehydration of more than about 2 percent of body weight, then, can be the difference between training hard enough to provide a strong stimulus for your body to improve and feeling like you are working harder but with less benefit.
A race-day hydration plan is key to running your best marathon.
Rebekah Downes/PA Images via Getty Images
MARATHONING AND CAFFEINE
Most runners have caffeine on a daily basis in coffee, tea, energy drinks, cola, or chocolate. Caffeine is part of daily life. It can also have a performance-enhancing effect, at least for some people.
A variety of studies have found performance-enhancing benefits from caffeine ingestion (Burke 2008; Gonçalves et al. 2017; Thomas, Erdman, and Burke 2016), and several have found no effect (Burke 2008). The different findings may depend on the study designs used but may also be related to recent findings (Guest et al. 2018) that an individual’s genotype for a gene that influences caffeine metabolism determines the effect of caffeine on their performance. Individuals who have the genotype that allows them to metabolize caffeine quickly typically get a performance-enhancing effect, while those with the intermediate genotype (moderate metabolizers) do not seem to receive a boost in performance. Those with the genotype associated with slow metabolism of caffeine typically perform worse after caffeine ingestion.
A few studies have found no performance-enhancing effect of caffeine for individuals who consume caffeine regularly (Bell and McLellan 2002; Burke 2008). This led to some athletes abstaining from caffeine for a week or two before competition to try to increase the performance-enhancing effect. More recent studies, however, have found a performance-enhancing effect from caffeine even for habitual users, particularly if they consume more caffeine prior to competition than their typical daily intake (Gonçalves et al. 2017). In fact, if you’re used to having a cup of coffee each morning, abstaining from coffee could have a detrimental effect on your performance because of the withdrawal effects of caffeine deprivation.
Extrapolating from run-to-exhaustion studies in the lab, the likely benefit of taking caffeine for individuals with the genotype for fast caffeine metabolism is in the range of 1 to 2 percent (perhaps 20 to 45 seconds in a 10K or 90 seconds to 4 minutes in a marathon). The effect of caffeine that is most likely to boost performance for marathoners is stimulation of the central nervous system, which increases alertness and concentration. There is intriguing evidence that central nervous system stimulation reduces perception of effort so that a given pace feels easier.
An appropriately conservative view is that runners should use caffeine with the intention of improving performance only if they are already training hard and intelligently, have an excellent diet, and are working to optimize other lifestyle factors that influence running performance. If you are doing everything else right and have the right genotype, a moderate dose of caffeine may allow you to gain a small improvement in performance. The International Olympic Committee Consensus Statement on dietary supplements for high-performance athletes (Maughan et al. 2018) reviewed the scientific literature and suggests a benefit to performance from 3 to 6 mg of caffeine per kilogram body weight consumed about an hour before exercise, although they mention that some studies find a benefit from lower levels of caffeine intake. A variety of gels, sports drinks, and other products contain specific levels of caffeine that are more dependable than estimating how much is in your cup of coffee.
The potential side effects of caffeine include headaches, dizziness, anxiety, nervousness, gastrointestinal distress, and heart palpitations. Athletes vary widely in their sensitivity to and tolerance of caffeine, so you are an experiment of one. If you do not regularly consume caffeine, you will likely be more sensitive to the effects. You may also not have the genotype that has a positive performance response to caffeine intake. If you are considering using caffeine for your marathon, practice using it during a few of your longest training runs to see how your body responds.
How Much to Drink
For any marathoner training in warm conditions, preventing excessive dehydration that decreases performance is a priority. How much you need to drink to stay well hydrated during your marathon preparation depends on a number of factors, including the heat and humidity, your body size, how much you’re training, how acclimatized you are to the conditions, and how much you sweat. Because sweat rates vary greatly between individuals, it is useful to figure out whether you are a moderate or heavy sweater so you can better plan your personal hydration needs.
On top of your baseline fluid needs, you need to add your fluid losses from training and other activities. Weigh yourself before and after running and calculate how much weight you lost, then drink with the objective of bringing your weight back up to normal. Becoming fully hydrated typically requires drinking about one and a half times the amount of weight you lost—the extra amount is required because some of what you drink will quickly wind up as urine. So, for example, if you lost 3 pounds (1.4 kg) during a training run, you would need to drink about 4.5 pounds (2 kg) of fluid (4.5 pints [2.1 L]) prior to your next run to be fully rehydrated. (Sodium in your food and drinks provides the benefit of enabling your body to retain more of the fluid you take in.)
Maintaining normal hydration levels from day to day requires some planning, particularly for those with normal jobs. Keeping a water bottle at your workstation is a must. You’ll maintain your hydration status most effectively if you discipline yourself to drink regularly throughout the day. Try to avoid waiting until shortly before training to replace your fluids—if you rush the process, you’ll go into your workout either bloated from too much fluid ingested too quickly or dehydrated from not having enough fluid. Once again, while not sweating profusely, your thirst mechanism is a good guide, but if you feel thirsty before the start of a run, your hydration level is likely somewhat low.
How much you should drink during your race is discussed in the “Marathon Race-Day Nutrition and Hydration” section later in this chapter.
What to Drink
During the many hours a day you’re not running, water should be your primary beverage. Few people need to sip sport or energy drinks throughout the day. Water and carbohydrate-replacement drinks that contain sodium are excellent for maintaining hydration during running. The advantage of replacement drinks with 6 to 8 percent carbohydrate is that they’re absorbed as quickly as water and also provide readily usable energy. The carbohydrate can help your performance during workouts lasting longer than 1 hour. The exact carbohydrate concentration that’s best for you will depend on your stomach’s tolerance and how warm it is during training and during your marathon. On a cool day, you may want to use a carbohydrate content of 8 percent, whereas on a warm day, when fluid is likely more critical than extra carbohydrate, you may want to use a drink with 6 percent carbs. Many sports drinks are now designed with more than one type of carbohydrate (typically glucose-fructose mixtures) to increase the rate that is absorbed in the intestines. Sports drinks should also contain at least 110 mg of sodium per 8 fluid ounces to enhance glucose and water absorption and improve fluid retention.
Some of the world’s top marathoners, including 2016 Olympic champion Eliud Kipchoge, now use a higher-carb Swedish drink, despite reportedly not having endorsement deals with the company. The drink comes in two concentrations: one providing 40 grams of carbohydrate per half liter (16.9 ounces), the other providing 80 grams of carbs per half liter (16% carbohydrate). Drinks with this much carbohydrate have traditionally been problematic for runners because their high concentration slows gastric emptying, leading to bloating and other gastrointestinal issues. The Swedish drink attempts to get around that problem by turning into a more easily dispersed hydrogel once it reaches the stomach. Scientific evidence on this drink is currently limited, but several studies are underway. It may be a passing fad, but if more evidence emerges suggesting a benefit, then, as with anything new, curious runners should experiment with the drink in training before using it on race day.
Attempting to do high-mileage or high-intensity training in hot weather is a physiological challenge that requires you to be flexible with your training schedule. By planning your training, you can minimize the impact of hot weather. Start each workout fully hydrated by making rehydration a priority after the previous day’s run. When possible, run at the time of day when the weather is the least taxing on your body. On a hot, humid day, slow your pace from the outset rather than waiting until your body forces you to slow.
MARATHONING AND ALCOHOL
Alcohol is part of many runners’ diets. Is that good or bad for your running performance?
Alcohol (ethyl alcohol) primarily affects your brain. One or two drinks temporarily lead to reduced tension and relief from stress. In the short term, they will also increase dehydration and slow down rehydration. Where to strike the balance? The night before your marathon, reduced tension is a good thing, but as discussed earlier, it is wise to avoid any amount of dehydration as you toe the starting line. With this in mind, it’s best to limit yourself to one or, at the most, two beers or one glass of wine the night before the marathon. Take in enough extra fluid to make up for the dehydrating effect of the alcohol. Drink an extra ounce (30 mL) of water for each ounce of beer and an extra 3 ounces (89 mL) of water for each ounce of wine that you drink. The same guideline holds for the night before a long run.
After training or racing, wait until you’re reasonably well rehydrated to enjoy a postrun potable. Imbibing while you’re still dehydrated from running will slow your recovery.
Alcohol has long been part of running lore. Former New York City Marathon winner Rod Dixon famously said, “All I want to do is drink beer and train like an animal.” There is great variance in how much alcohol runners can tolerate. How much is too much? Be honest with yourself about whether drinking regularly detracts from your running such as by lowering your sleep quality or making you groggy and dehydrated when you wake. And right before training or racing, well, let’s not go there.
CARBOHYDRATES AND THE MARATHONER
The main fuels for endurance exercise are carbohydrate and fat. Protein also provides a small amount of energy. Carbohydrate supplies the majority of your energy during the marathon, and fat supplies the bulk of the remainder. If you want to run 26.2 miles (42.2 km) at a good pace, you had better like carbohydrate foods, because they’ll be a mainstay of your diet during most of your day-to-day training and especially in the final few days before the marathon.
Even if you’re a gaunt marathoner, your body has a large stockpile of energy in the form of fat. A 140-pound (64 kg) runner with a body fat level of 6 percent still carries around 8.4 pounds (3.8 kg) of fat. Each pound of fat supplies 3,500 calories of energy, so this individual has more than 29,000 calories stored as fat.
For the purposes of fast marathoning, what matters are your reserves of carbohydrate, not fat, and your carbohydrate stores are much more limited. If you do a good job of carbohydrate loading, you can store about 2,000 to 2,500 calories of glycogen (the body’s storage form of carbohydrate).
When you run, your body burns a mixture of carbohydrate and fat. The harder you run, the higher the proportion of carbohydrate you use; the slower you run, the higher the proportion of fat you use. During walking, more than half of the calories you burn are provided by the breakdown of fat. As your pace increases, you use proportionately less fat and more carbohydrate. An easy recovery run may be fueled by 60 percent carbohydrate and 40 percent fat. When you race the marathon, over 75 percent of the fuel you use is supplied by the breakdown of carbohydrate. For those jogging the marathon, the proportion of carbohydrate used may be somewhat lower.
Carbohydrate is a more efficient energy source than fat. The breakdown of fat requires more oxygen per calorie released than does carbohydrate. Because fat metabolism doesn’t produce energy aerobically as efficiently as carbohydrate metabolism does, you can’t run as fast when burning just fat.
Your body uses several strategies to keep you from running out of carbohydrate stores. One of these strategies is to use relatively more fat as your carbohydrate stores become low. When your glycogen stores become critically low, you experience “hitting the wall” or “bonking.” A problem with glycogen depletion is that there aren’t warning signs that it’s going to occur until it’s too late. When you need to slow suddenly in a marathon, the culprit is probably glycogen depletion, not dehydration, which tends to affect you more gradually.
You can prevent carbohydrate depletion by glycogen loading. Glycogen loading (also known as carbohydrate loading) is the practice of manipulating your diet and training to increase your glycogen stores.
Marathoners can increase their glycogen stores for race day by tapering training and eating a high-carbohydrate diet for 2 to 3 days before the race as recommended in the training programs in chapters 9 through 13.
Rice, pasta, bread, sweet potatoes, pancakes, bagels, potatoes, corn, and raisins are excellent sources of carbohydrate. Expect to gain a couple of pounds and feel slightly bloated when you glycogen load, because your body stores 2.6 grams of water for every gram of glycogen. The added weight shows that you have done a good job of glycogen loading, and the stored water may help prevent dehydration as the marathon progresses.
If you eat a normal runner’s diet, with about 60 percent of your calories from carbohydrate, you probably store about 1,500 to 2,000 calories of glycogen in your muscles. If you glycogen load, however, your muscles have the capacity to store about 2,000 to 2,500 calories of glycogen. Each mile (1.6 km) that you run burns about 90 to 140 calories, depending on your weight and metabolism, and over 75 percent of those calories are supplied by carbohydrate. If you do a great job of loading, you’ll have just about enough glycogen for the marathon.
Glycogen loading is also useful before your long runs so you have plenty of fuel to go the distance. Carbohydrate loading before your long runs will help ensure that those runs are high quality, which will increase your confidence for the marathon. For some of your long runs, however, it may be beneficial to allow your glycogen tank to run low to stimulate increased glycogen storage. This strategy, called train low/race high, is explained in the following sidebar.
TRAIN LOW/RACE HIGH
In chapter 1, we discussed that one of the adaptations to endurance training is the ability to store more glycogen. This occurs because running low on glycogen provides a stimulus for increased activity of the glycogen synthase enzyme, which leads to increased glycogen storage. Recent evidence suggests that there may be other benefits of allowing your glycogen stores to run low during some of your training runs, including increased mitochondrial content, increased aerobic enzyme activity, and increased ability to oxidize fat (Burke 2010; Stellingwerff 2013).
Elite distance runners have used this “train low” approach for decades (without understanding the scientific rationale) by doing long runs in the morning with little or no carbohydrate intake and running twice per day with their glycogen stores partially depleted during the second workout of the day.
The most convenient way to train low is to do a long training run in the morning before breakfast (or after a very small breakfast) or at least 6 hours after a meal. It is
not yet clear how much or how often depletion is needed to stimulate these adaptations, but as with any change to your training, try this approach cautiously so you have plenty of energy for most of your training. With glycogen depletion there is a risk of delayed recovery from training and of immune system suppression.
Allowing your glycogen stores to run low (but not become entirely depleted) once or twice per week may provide a useful balance between gaining the positive adaptations from training low without it becoming a drag on your enthusiasm for training. Start with a moderately long run without stocking up on carbs before or taking carbs during the run, and progressively increase the length or intensity of the run from week to week. If you feel a bit more fatigued than usual in the last couple miles of your run, you have probably gauged it about right. If you feel wiped out during the latter stages of your run and need a couple days’ recovery, you have overdone it and should start with a shorter, easier run.
How Much Carbohydrate Do You Need in Your Daily Training Diet?
Your daily carbohydrate requirement depends on your weight and how much you’re training. If you’re averaging an hour to an hour and a half of training per day, you need approximately 2.3 to 3.2 grams of carbohydrate per pound (5-7 g/kg) of your body weight per day. If you’re training for an hour and a half to two hours per day, you need approximately 3.2 to 3.9 grams of carbohydrate per pound (7-8.5 g/kg) of body weight per day. Training for 2 hours or more per day requires at least 3.6 grams of carbohydrate per pound (8 g/kg) of body weight per day.
As an example, say Gary is running 80 miles (129 km) per week and weighs 154 pounds (70 kg). His average daily training time is about 80 minutes. Gary’s daily carbohydrate requirement is 350 to 490 grams (70 × 5 to 70 × 7). Each gram of carbohydrate supplies 4.1 calories, so Gary’s calorie supply from carbohydrate should be about 1,400 to 2,000 per day.
SHOULD YOU GO GLUTEN-FREE?
For much of the modern marathon era, runners took a more-is-better approach to gluten, or at least to the foods it’s most commonly found in—pasta, bread, bagels, muffins, and the like. More recently, the pendulum has swung in the other direction. One survey (Lis et al. 2015) of predominantly competitive endurance athletes found that 40 percent avoid gluten, far greater than the portion of the population thought to be diagnostically gluten sensitive. Anecdotally, you may have encountered many fellow runners who say they try to avoid gluten. As in most matters in running, the best approach for most people lies somewhere between the extremes.
Gluten is a protein found in wheat, barley, and rye. In North America and Europe, 1 percent of the population has celiac disease, an autoimmune disorder in which eating gluten causes damage to and inflammation in the small intestine. Untreated celiac disease can lead to poor nutrient absorption and a cascade of symptoms (diarrhea, bloating, fatigue, osteoporosis) that can harm normal health, not to mention marathoning. The best treatment for celiac disease is a strict gluten-free diet. High-level marathoning on such a diet is possible, as evidenced by the success of runners such as Stephanie Bruce, an American with a personal best below 2:30.
Things get a little trickier when the topic is gluten sensitivity or gluten intolerance. It’s estimated that about 5 percent of the population have some degree of sensitivity or intolerance. Some of the symptoms are similar to those of celiac disease, such as fatigue, headaches, and gastrointestinal issues. But there’s no reliable test for the condition. And it’s quite possible that many people’s symptoms aren’t caused by gluten per se. For example, bloating could stem from eating too much fiber, which glutenous foods such as whole-wheat bread are usually high in. Similarly, a challenging workout like a long tempo run will mean blood is diverted from your stomach, potentially leading to short-term trouble digesting glutenous foods. Eating the same foods long after the run might not cause symptoms.
If you’re not gluten sensitive, you might think there’s no harm in going gluten-free. But there’s unlikely to be gain, either. In general, dietitians don’t recommend avoiding an entire class of food without good reason. If you think you might have gluten sensitivity or intolerance, start by keeping detailed records of your diet, symptoms, and running performance to see if you can identify trends. If you decide you might be in the small minority of the population with the condition, consult a sports nutritionist.
High-Fat/Low-Carb Diets
Much has been written over the past several years on high-fat/low-carb (HFLC) diets for endurance athletes. A typical HFLC diet calls for 50 to 75 percent of calories from fat, up to 20 percent of calories from protein, and less than 50 grams per day from carbohydrates. The more extreme versions are also called ketogenic, or keto, diets because these diets increase ketosis, which occurs when the body metabolizes fat at a high rate and converts fatty acids to ketones. A number of ultraendurance athletes have switched to a HFLC diet, and a growing number of studies are looking into the impact of these diets on the metabolism of fat, weight loss, blood lipid levels, and performance.
Studies have found that a HFLC diet increases fat oxidation even if the athlete is only on the diet for a short time (Havemann et al. 2006). Longer-term studies have found an increased proportion of fat oxidation at higher exercise intensities; in other words, subjects burned relatively more fat at higher exercise intensities while on a long-term HFLC diet (Volek et al. 2016). Theoretically, this adaptation could help when racing a marathon in that you wouldn’t burn as much glycogen at a given pace and could therefore reduce your risk of hitting the wall.
Evidence of the impact of switching to a HFLC diet on cholesterol and triglyceride levels is mixed and may depend on what types of fats are emphasized in the diet. Subjects also tend to lose several pounds on a HFLC diet (McSwiney et al. 2018; Urbain et al. 2017; Zinn et al. 2017), likely due to less storage of water with lower glycogen stores and ketosis, and some maintain a lower body weight over time. For individuals with type 2 diabetes or high blood glucose levels, a HFLC diet may lead to reduced and stabilized blood sugar levels due to reduced production of insulin. On the other hand, there is evidence that exercise economy (the equivalent of running economy) is decreased on the HFLC diet, meaning more oxygen is required to maintain a given speed (Impey et al. 2018). There is currently no evidence that a HFLC diet will improve marathon performance compared to a high-carbohydrate diet.
Studies and anecdotal evidence have found that runners feel fatigued and endurance performance decreases in the first few weeks on a HFLC diet but that the fatigue decreases over time and endurance performance gradually returns to its normal level (Urbain et al. 2017; Zinn et al. 2017). As would be expected, studies have found that high-intensity exercise performance decreases on a HFLC diet, so the ability to do interval workouts such as 1200-meter repeats at 5K race pace would be impaired (Urbain et al. 2017; Havemann et al. 2006). It is not clear whether training at the intensity required for lactate threshold workouts (e.g., tempo runs) can be conducted as effectively on a HFLC diet, but with long-term adaptation that may be the case.
Currently, there is not enough evidence to recommend that marathon runners, particularly those who are trying to maximize their performance, switch to a HFLC diet. To date, the majority of evidence supports the view discussed in this chapter that carbohydrates are the primary fuel source for marathon training and racing. In coming years, more evidence will emerge on this interesting topic, but for now it is premature to change from the conventional approach of providing enough carbohydrates to fuel your training.
Tips to Replenish Your Glycogen Stores
If you follow a typical runner’s high-carbohydrate diet, you probably have enough glycogen to get you through a 20- to 22-mile (32-35 km) run or a hard interval workout. After a long run or a long interval workout, therefore, your glycogen stores are depleted. It typically takes 24 to 48 hours to completely replenish your glycogen stores. When you do two long or hard workouts in a row, therefore, you risk going into the second workout with partially filled glycogen stores, becoming depleted, and having a bad workout. The frequency with which you can train hard is determined by your recovery rate between workouts, and this will be increased by replenishing your glycogen stores quickly.
Here are strategies you can use to increase your rate of glycogen replenishment.
Don’t wait. Your body stores glycogen at a faster rate during the first two hours after exercise and at the fastest rate during the first 30 minutes after exercise, so have a carbohydrate drink with you when you finish your long runs or other glycogen-depleting workouts. Bring along some easy-to-digest carbohydrate foods as well. To speed glycogen resynthesis, take in a little under half a gram per pound of body weight (1 g/kg) in the first 30 minutes after the workout and another gram per pound of body weight during the following 2 hours, and have a meal within 3 hours of finishing training.
Increase your intake of carbohydrate. After a glycogen-depleting workout, increase your carbohydrate intake to at least 3.6 grams per pound of body weight (8 g/kg) during the next 24 hours.
Eat moderate– or high–glycemic index foods during the first few hours. The glycemic index of a food is determined by the effect it has on your blood glucose level. High–glycemic index foods cause a large increase in blood glucose levels, whereas low–glycemic index foods have a lesser effect. During the first few hours after a workout, your
glycogen stores will be replenished more quickly if you consume moderate– or high–glycemic index foods, such as sports drinks, recovery bars, fruit bars, potatoes, rice cakes, bread, bagels, raisins, and crackers.
Consume some protein with your carbohydrates. A small amount of protein (e.g., 15-20 g) consumed with carbohydrates has been found to increase glycogen storage and also stimulates protein synthesis for muscle repair.
Nancy Clark’s Sports Nutrition Guidebook and Endurance Sports Nutrition by Suzanne Girard Eberle are excellent and extensive resources for more information on nutrition for endurance athletes.
THE ROLE OF PROTEIN FOR MARATHONERS
Conventional wisdom indicates that strength-trained athletes such as weightlifters need lots of extra protein to build muscle but that the protein needs of endurance athletes are the same as for sedentary folks. Over the past several years, however, studies have clearly shown that endurance athletes have elevated protein needs. As a marathoner, your body needs protein to repair damaged muscles, make red blood cells to deliver oxygen to your muscles, make mitochondria in your muscles to produce energy aerobically, maintain a strong immune system, and make enzymes and hormones that keep your body functioning normally.
Sedentary individuals need about 0.35 to 0.45 gram of protein per pound of body weight per day (0.8-1.0 g/kg per day). Endurance athletes have elevated protein needs because of their greater wear and tear on muscle tissue and red blood cells, need for more mitochondria, and so on. Several formulas are used for calculating the protein needs of endurance athletes. The American College of Sports Medicine guideline for protein intake for endurance athletes had previously been 0.55 to 0.64 grams of protein per pound of body weight, but this range was recently broadened to take into account the specifics of the athlete’s training and the timing of protein intake (Thomas, Erdman, and Burke 2016). In the aforementioned Endurance Sports Nutrition, sports dietitian Suzanne Girard Eberle provides a guideline of 0.55 to 0.75 grams of protein per pound of body weight (1.2-1.7 g/kg of body weight) per day for endurance athletes. Table 2.1 presents daily protein requirements for marathoners using this formula.
Although the protein intake of most Americans exceeds their requirements, this is not necessarily the case for marathoners, particularly those who restrict some aspect of their diets. For example, if you’re a vegetarian, it’s not difficult to meet your protein requirements, but it does require some knowledge and planning.
Eating too much protein can also have negative consequences for your running performance. If you eat too much protein, you may not be consuming enough carbohydrate, so such a diet would reduce your energy levels. Your body would use the excess protein as energy by removing the amino groups and oxidizing the resulting carbon skeleton. This process requires the removal of waste products, which can stress the kidneys.
TABLE 2.1
Daily Protein Requirements for Marathoners
Weight (lb)
Weight (kg)
Protein required (g/day)
100
45
55-75
120
55
66-90
140
64
77-105
160
73
88-120
180
82
99-135
200
91
110-150
THE IMPORTANCE OF IRON
Iron is vital to running performance. Despite this importance, many runners don’t monitor their iron levels.
Iron is necessary for producing hemoglobin in your red blood cells. Oxygen attaches to hemoglobin for transport in your blood to your muscles. If your hemoglobin level is low, less oxygen reaches your muscles, which means your muscles can’t produce as much energy aerobically. The result is that your O2max and lactate threshold are reduced, and you can’t maintain as fast a pace. In addition, iron is a component of many other substances in the body, such as enzymes in your muscle cells that affect aerobic energy production, so low iron levels may cause low energy levels by altering production of these other substances.
For many years, top athletes and coaches have recognized the benefits of a high red blood cell count; this awareness has led to the illegal practices of blood doping and using synthetic
erythropoietin (EPO) to increase red blood cell count. EPO is a hormone the body produces naturally that determines the body’s level of red blood cell production. When EPO levels rise through natural means or through injection of synthetic EPO, red blood cell production and hemoglobin levels increase. The result is that the runner can produce more energy aerobically and, therefore, maintain a faster pace.
The typical marathoner needs to ensure that he or she doesn’t have a low red blood cell count or low iron stores. Low iron levels may be the most prevalent nutrition deficiency in Western marathoners, particularly for women. With iron-deficiency anemia, your iron stores are gone and your hemoglobin level is reduced. With iron depletion, on the other hand, your iron stores are low but not gone, and your hemoglobin is still in the normal range. Although anemia is more detrimental, both of these conditions can negatively affect your running performance.
Why Do Marathoners Tend to Have Lower Iron Levels?
Runners may have slightly lower hematocrit and hemoglobin levels than do sedentary folks due to increased blood volume. Runners may have relatively low iron stores due to low iron intake, foot-strike hemolysis, damage to red blood cells from muscle contraction, and iron loss through sweat and urine and through the gastrointestinal (GI) system. For marathoners, the iron losses tend to be higher than for those doing shorter races, primarily because of higher training volumes. Let’s look at each of these factors.
◼ Increased Blood Volume. Endurance athletes have more blood than do normal people. This adaptation allows the stroke volume of the heart to increase, which allows O2max to increase. This is a good thing. The iron in a runner’s red blood cells, therefore, is diluted in a greater volume of blood. If the runner’s red blood cell mass doesn’t increase as much as the blood volume, hemoglobin concentration will decrease and may incorrectly indicate an iron deficiency.
THE NO-MEAT MARATHONER
People follow a vegetarian or vegan diet for many reasons—primarily health, ethical, or environmental—but few do so primarily to improve their running. Is it possible to run your best marathon while not eating animals or, in the case of veganism, not eating any animal products?
The short answer is yes, but you will probably have to pay more attention to your diet than would otherwise be the case.
That extra attention isn’t necessarily a negative. Of course, you could live on candy bars and potato chips and call yourself a vegetarian, but that isn’t the approach most take. Following a plant-based diet usually means greater awareness of the nutritional value of foods and striving to eat high-quality, nutrient-dense items. This might be one reason that in general health measures such as cholesterol and body mass index, vegetarians and vegans tend to have better profiles than the average person.
But what about marathoning? The few studies (Craig and Mangels 2009; Nieman 1999) that have compared vegetarian athletes to omnivorous athletes have found the groups to be roughly similar in measures such as thigh muscle size and lung function. There is also no evidence that a well-planned vegetarian or vegan diet will lead to being deficient in protein.
As noted on page 46, the biggest potential challenge for marathoning vegetarians and vegans has to do with iron. Only about 10 percent of iron from plant sources is absorbed, compared to almost twice as much from meat sources. And that assumes you’re regularly eating large amounts of iron-rich plants, such as spinach and kale. The same problem of lesser bioavailability from plant sources occurs with some macronutrients that have a role in endurance performance, such as vitamin B12, zinc, and omega-3 fatty acids. Vegans can also be short on calcium, which plays a role in bone health.
For these reasons, it is likely worth consulting a dietitian to ensure you are meeting your nutritional requirements if it’s important to you to follow a vegetarian or vegan diet.
Shalane Flanagan
Fastest marathon: 2:21:14 (Berlin, 2014) Marathon highlights: 1st place, 2017 New York City Marathon; 1st place, 2012 U.S. Olympic Trials Marathon; 6th place, 2016 Olympic Marathon; 10th place, 2012 Olympic Marathon
Shalane Flanagan began 2017 with a stress fracture in her back. She ended 2017 as the first American woman in 40 years to win the New York City Marathon. That trajectory perfectly captures the patience, persistence, and self-belief underlying Flanagan’s legendary career.
Flanagan has always risen to the level of her competition, whether while winning a high school national indoor championship, NCAA cross-country titles, and U.S. Olympic Trials races on the track, or medaling at 10,000 meters in the 2008 Olympics. So it was no surprise when she nailed her marathon debut, placing second against some of the world’s best at New York City in 2010. Given her standards for herself, it was also no surprise that Flanagan then set the goal of winning a major marathon.
One interesting aspect of her quest to meet that goal is that she didn’t immediately switch to a traditional regimen of two marathons a year. Flanagan continued to compete in cross country (she won bronze at the 2011 World Championship) and on the track (she ran the outdoor world meet as late as 2015). There are two lessons to draw from this approach.
First, Flanagan focused on shorter distances because they were still a passion of hers. (She still holds the U.S. indoor records at 3,000 and 5,000 meters.) There is no rule saying that once you start running marathons, you’re not allowed to step away from the distance and enjoy other aspects of running. You’re more likely to run your best marathon when you view the distance with enthusiasm, not obligation.
Second, Flanagan is one of many runners who have gotten faster at shorter races after becoming marathoners. She set her U.S. road records for 10K and 15K in 2016 and 2014, respectively. Being a more complete runner helps, rather than hurts, your marathoning.
Flanagan, a Massachusetts native, set her sights on winning Boston after placing 10th in the 2012 Olympic Marathon. She first raced in Boston in 2013, when she placed fourth. The following year, she ran aggressively from the start to ensure a fast pace. Flanagan led through 19 miles before finishing sixth. A slight consolation was that her time that day, 2:22:02, remains the fastest on the course by an American woman in race history.
In the fall of 2014, Flanagan went to the Berlin Marathon to try to break Deena Kastor’s American record of 2:19:36. She was on pace for that mark as well as the win until the final 10K, when she slipped to third. A personal best of 2:21:14 again provided some consolation, but Flanagan remained eager for an international marathon win. She returned to Boston in 2015, but was never a factor en route to placing ninth. The Olympic year of 2016 meant running the U.S. trials in February and the Rio Games in August, so Flanagan couldn’t take another shot at Boston or New York City. She did finish sixth, however, at the Olympics, leading the way for a strong U.S. team performance resulting in all three women placing in the top 10.
Imagine Flanagan’s frustration, then, when the lower-back discomfort she felt early in 2017 was diagnosed as a stress fracture. She had to take several weeks off from running and withdraw from that spring’s Boston Marathon. With Flanagan’s 36th birthday approaching, even some of her most stalwart fans wondered if her time for winning a major marathon had passed.
Flanagan continued to believe otherwise. That belief was so even though her return marathon, New York City in 2017, featured Mary Keitany, who had won the three previous editions and earlier that spring had become the second-fastest female marathoner in history. Flanagan ran confidently and patiently through the first 20 miles, covering Keitany’s key moves but making none of her own.
Then, when she sensed Keitany was struggling, she seized the opportunity. She pushed hard, then harder, running some of her final miles in just over 5:00, or close to her 10K race pace. With a fist pump and a shouted expletive just before the finish, Flanagan captured the joy and satisfaction of any runner meeting a years-long goal. The New York City Marathon title was hers.
Before winning New York City, Flanagan had talked about retiring, especially if she won. But she found she still wanted to train for and race marathons. Any notion of her phoning it in was disproved by her fighting through horrific weather to finish seventh at Boston in 2018, then running with Keitany as long as possible and placing third in her New York City title defense. As she did throughout her career, Flanagan showed the best way forward is to follow your heart.
◼ Low Iron Intake. Many endurance athletes have low iron intakes. Low iron intake can be a problem for vegetarians and runners who eat red meat less often than once a week. The typical high-carbohydrate, low-fat, low-cholesterol runner’s diet often includes little or no red meat. Red meat contains heme iron, which is more easily absorbed than plant sources of iron. Runners who don’t eat meat can obtain sufficient iron through dietary sources but only by carefully selecting their foods. Enette Larson-Meyer’s book Plant-Based Sports Nutrition (2019) is a good resource for more information on proper nutrition for athletes who limit or avoid meat. The No Meat Athlete Cookbook by Matt Frazier and Stepfanie Romine is a good recipe source. For more on marathoning while following a vegetarian or vegan diet, see the sidebar “The No-Meat Marathoner.”
◼ Foot-Strike Hemolysis and Damage from Muscle Contractions. Foot-strike hemolysis is the breakdown of red blood cells when the foot hits the ground. Foot-strike hemolysis is potentially a problem for marathoners who run high mileage on asphalt or are heavier than most runners. In addition, recent evidence from athletes across a range of sports suggests that muscle
contractions from heavy training loads can also damage red blood cells.
◼ Iron Loss Through Sweat and Urine. A relatively small amount of iron is lost through sweat and urine, but for high-mileage runners training in hot, humid conditions, this iron loss may add up. For marathoners living in the South or training through the summer in preparation for a fall marathon, sweat may be a significant source of iron loss.
◼ Iron Loss Through the GI System. Loss of iron through the GI tract (primarily the stomach or large intestine) is a problem for some marathoners. Low levels of GI bleeding occur in some runners, especially during prolonged or high-intensity training. The bleeding is fairly minor each time and generally not noticeable, but there may be a cumulative effect over years of running.
All the preceding factors in combination make it important for marathoners to monitor their iron intake and their iron levels. The highest risk occurs in premenopausal female runners, whose iron intake often doesn’t meet their needs.
How Do You Know if You Have Low Iron?
If you have low iron, first, you’ll be dragging. Your heart rate may be elevated, and your enthusiasm for running will have sunk. You may also feel cold much of the time and have generalized fatigue throughout the day. These symptoms tend to come on gradually, however, so you may not suspect that you have low iron levels until they’ve had a large impact on your training. You can confirm your suspicions only with a blood test. You should find out your hemoglobin level (the iron in your red blood cells) and your serum ferritin level (your body’s iron stores).
Normal hemoglobin concentration ranges vary between countries and labs but are typically from 14 to 18 grams per deciliter (g/dL) of blood for men and 12 to 16 g/dL of blood for women; for an endurance athlete, the lower end of normal should be extended by about 0.5 g/dL because of his or her larger blood volume.
Normal reference serum ferritin levels also vary between countries and labs but are typically 12 to 200 nanograms per milliliter (ng/mL) for women and 12 to 300 ng/mL for men. Conflicting schools of thought exist on the relationship between ferritin levels and running performance. One opinion is that ferritin levels aren’t directly related to performance, but if your ferritin level falls, eventually your hemoglobin and performances will decline too. Low ferritin, therefore, can be viewed as an early warning sign.
The other school of thought is that ferritin also reflects the iron stores the body can use to make enzymes for oxidative energy production; therefore, they have a direct impact on performance. The level of serum ferritin below which performance is affected seems to differ among individuals. Physiologists have found that training and racing performance is frequently impaired when serum ferritin levels fall below 20 ng/mL, whereas a serum ferritin between 20 and 40 ng/mL may be low or normal depending on the runner’s individual physiology (Eichner 2012; Peeling et al. 2008; Schumacher, Schmid, and Grathwohl 2002). A sports doctor can provide expert guidance if your iron levels are borderline or low.
How Much Iron Do You Need?
The U.S. recommended daily intake (RDI) for premenopausal women is 18 milligrams of iron a day, compared to 8 milligrams of iron a day for men and postmenopausal women. According to the American College of Sports Medicine’s 2016 Position Stand on Nutrition and Athletic Performance, iron requirements for women athletes may be up to 70 percent higher than for nonathletes, and distance runners and vegetarian athletes should be screened regularly and maintain iron intakes higher than the RDI (Thomas, Erdman, and Burke 2016). Iron requirements haven’t been established for high-mileage runners, so all that can be said with confidence is that marathoners need at least the RDI. As with any mineral, too much iron can be a health hazard. In fact, the typical American man is more likely to get an iron overload than to be iron deficient.
How Can You Prevent Iron Depletion?
As with other running problems such as injuries, the best strategy is to avoid low iron in the first place. Good food sources of iron include liver, lean red meat, poultry dark meat, fish, oysters, egg yolk, dark green leafy vegetables, legumes, dried fruit, lentils, and whole-grain or enriched cereals and bread.
The following guidelines can help increase iron absorption to prevent iron deficiency.
Eat 3 ounces (85 g) of lean red meat or dark poultry at least 3 times per week.
Don’t drink coffee or tea with meals because they reduce iron absorption.
Eat or drink foods rich in vitamin C with meals to increase iron absorption.
Have meals containing both heme iron (from animal sources) and nonheme iron to
increase absorption of the nonheme iron.
Eat iron-enriched breakfast cereals.
Use cast-iron cookware (particularly for acidic foods such as spaghetti sauce).
Although these recommendations may seem like subtle changes in diet, they can have a powerful effect on your iron levels. For example, you’ll absorb three times as much iron from your cereal and toast if you switch from coffee to orange juice with breakfast. Women distance runners may consider taking iron supplements after consultation with their physician, only if necessary after making the recommended dietary changes.
SUPPLEMENTS AND OTHER POTENTIAL ERGOGENIC AIDS
There are myriad types of nutritional supplements, with more coming on the market each year. Unfortunately, many are backed by false or exaggerated claims, and the supplement industry is not well regulated in most countries, including the United States. In addition to wasting your money, taking supplements poses a risk of negative side effects. Let’s look briefly at several major categories of nutritional supplements.
Protein Supplements
As discussed earlier in this chapter, marathoners have higher protein requirements than sedentary people, but these moderately increased requirements are easily met by a well-balanced diet. Most runners don’t need to take protein supplements to meet their needs.
Vitamin and Mineral Supplements
Meeting your baseline need for vitamins and minerals is important for good health and for positive adaptation to training. This is easily accomplished without supplements for runners who eat a healthy diet. Runners whose diets may be deficient in certain key vitamins and minerals, however, should consult with a doctor or appropriately qualified sports dietitian. Vegetarians, for instance, often have a difficult time getting enough iron (as previously discussed), zinc, and vitamin B12 from natural food sources, and they may also be low in omega-3 fatty acids. In that instance, appropriate nutritional supplements might prove beneficial to their running and overall health. More is not better, however, and excessive supplementation with minerals and fat-soluble vitamins can be toxic.
During the winter, the recommended 1,000 international units (IU) of vitamin D can be difficult to obtain through sunlight and diet alone. That’s especially true if you work a normal schedule and do almost all of your running in the dark for a few or more months per year. Insufficient vitamin D levels can suppress your immune system, thereby potentially leading to catching more colds and generally not recovering from your training as well. A doctor or dietitian may recommend a vitamin D supplement for marathoners in this situation.
You also need to be mindful of the ways isolated vitamins and minerals in supplements may interact with one another, which is another reason we strongly recommend taking the advice of a doctor or dietitian before consuming supplements. Trying to time your supplements so they don’t interfere with one another is a hassle you don’t need. Better to just avoid nutritional deficiencies by eating a well-rounded diet.
Other Nutritional Supplements
This category includes the hundreds of nutritional supplements on the market claiming to improve various aspects of athletic performance. Among these, most focus on strength and power performance, but an increasing array is marketed toward endurance athletes. Decades of experience has shown that spending your hard-earned cash on miracle cure supplements is a monumental waste. To run your best, stick with a healthy diet and lifestyle combined with intelligent training, and steer clear of quick fixes claiming to enhance running performance.
According to the 2018 IOC Consensus Statement: Dietary Supplements and the High-Performance Athlete, which reviewed the evidence behind hundreds of types of supplements, two potential exceptions in this regard are caffeine and nitrate (Maughan et al. 2018). We’ve discussed caffeine elsewhere in this chapter. You may not have heard about nitrate, but you’ve probably heard about the performance-enhancing promise of beet juice. Well, beet juice is rich in nitrate, which is converted to nitrite by the saliva in your mouth, which then is converted to nitric oxide in your body. Nitric oxide is said to improve various running-related processes, such as muscle contraction and blood flow. Some research has found that, after drinking beet juice, athletes’ oxygen consumption is a little lower at a given workload (in other words, maintaining that pace is a little easier) (Bailey et al. 2009; Jones 2014). There is some evidence that beet
juice, with its not-great taste and potential for causing digestive issues, may be more effective than an isolated nitrate supplement (Flueck et al. 2016).
It’s not yet clear exactly what produces the beet juice effect, what the right amount might be for most people, and whether the effect is universal. Some studies (Wilkerson et al. 2012) have found that the fitter the subjects, the smaller the effect. As with almost all nutritional matters, be cautious and don’t look at beet juice as a magic bullet.
MARATHON RACE-DAY NUTRITION AND HYDRATION
So you’ve followed the advice in this chapter by eating properly and staying well hydrated throughout your months of preparation. Guess what—your work isn’t done yet. Your strategies for taking calories and fluid on race day can have a strong influence on your marathon performance.
Let’s assume you’ve done a good job of glycogen loading during the previous several days and you’re well hydrated. Before the race, you want to take in between 200 and 500 calories of mostly carbohydrate to top off your glycogen stores. It’s best to ingest these calories 3 to 4 hours before the race. This shouldn’t be a big deal for races with late starts, such as New York City or Boston, which have wave starts beginning at 10 a.m. But for a race such as Chicago, which starts at 7:30 a.m., or Honolulu, which starts at 5:00 a.m. (!), you may have to get up a bit on the early side, eat something, and then try to doze a while longer. (Good luck with that on race morning!) You should also take in about a pint (0.5 L) of fluid to replace fluids lost overnight and ensure that you’re fully hydrated.
Even if you carefully carbohydrate load for several days leading up to the marathon, you don’t have much of a buffer against glycogen depletion. The solution is to take in additional calories during the race.
How much you need to drink during the marathon depends on your body size, the heat and humidity, and your sweat rate. The target is to replace the fluid you lose from sweating so you do not lose more than 2 percent of your body weight during the marathon. As we will see later, that is a challenging target to achieve, particularly on a warm day. The maximum amount you should drink during running is the amount that can empty from your stomach or the amount required to avoid excessive dehydration from sweat loss, whichever is less. Drinking more than you have lost brings the risk of hyponatremia, which is discussed later in the chapter.
Research has shown that runners’ stomachs can typically empty only about 6 to 7 ounces (177-207 mL) of fluid every 15 minutes during running, representing about 24 to 28 ounces (710-828 mL) per hour. If you drink more than that, the extra fluid will just slosh around in your stomach and not provide any additional benefit. You may be able to handle more or less than the average, however, so experiment with how much liquid your stomach will tolerate.
During training, it’s relatively easy to stop and drink as much as you want whenever you feel like it. All that’s required is a bit of planning and perhaps a few containers strategically placed before your long run. During the marathon, however, it’s very difficult to drink 6 to 7 ounces (177-207 mL) of fluid at an aid station without stopping. In fact, a study by Dr. Tim Noakes and colleagues (2007) found that most runners drink less than 16 ounces (473 mL) per hour when racing.
For serious marathoners going for a personal best time, if you drink 3 ounces (89 mL) at 8 to 10 drink stops during your marathon, you will have done a typical job of hydrating. Let’s look at fluid balance and carbohydrate intake from a practical level of 24 to 30 ounces (710-887 mL) of fluid intake during the marathon. If you run the marathon in 3 hours and are losing 3 pounds (1.4 kg) per hour, you will lose 9 pounds (4 kg) and take in 1.5 to 2 pounds (0.7-0.9 kg), for a net loss of 7 to 7.5 pounds (3.2-3.4 kg). If you weigh 150 pounds (68 kg), you will have lost 4.7 to 5 percent of your body weight; this will likely contribute to slowing down moderately late in the race.
Drinking 24 to 30 ounces (710-887 mL) of an 8-percent solution will supply 56 to 72 grams of carbohydrate. Each gram of carbohydrate contains 4.1 calories, so you’ll be taking in 230 to 295 calories during the race.
A complementary method of taking in carbohydrate during the marathon or your long runs is to use energy gels. Depending on the brand you choose, each gel packet typically contains between 80 and 120 calories of carbohydrate. You should follow most gels with a couple of sips of fluid to wash them down, and you should take in approximately 4 to 6 ounces (118-177 mL) of water afterward to help absorb the gel. Some gels, however, are isotonic (check the label), so you do not need to take in fluid to help with absorption. The best time to take an energy gel that is not isotonic is shortly before an aid station.
As always, don’t wait until race day to try an energy gel because it takes practice to get the water intake right and to feel comfortable running after taking a gel. You should develop a plan
for taking in sports drinks and gels during your marathon. The makeup of your personal plan will depend on how warm and humid your marathon is likely to be, how much carbohydrate you intend to take in during the race, and what types of carbohydrate you are most comfortable taking while running. A typical plan for a sub-3-hour marathoner would be to drink 24 to 30 ounces (710-887 mL) of a sports drink with 8 percent carbohydrates, divided between 8 to 10 aid stations, and to take gels providing 100 calories of carbohydrates each at about 1 and 2 hours into the marathon. This plan would supply 430 to 495 calories of carbohydrates. During the marathon, a typical 140-pound (63 kg) male burns about 100 calories per mile. Of those 100 calories, about 80 are supplied by carbohydrate. This plan, therefore, supplies enough carbohydrate fuel to last an extra 5 to 6 miles (8 to 10 km) and substantially boosts your likelihood of reaching the finish line without running critically low on glycogen. Slower marathoners can further boost their carbohydrate intake by taking another gel after about 3 hours (and after 4 if you’re still going).
Recent evidence (Burke and Maughan 2015) has found that even just rinsing your mouth with a carbohydrate drink can enhance performance. The mechanism seems to be that receptors in the mouth sense the carbohydrate and signal reward centers in the brain. You can use this strategy as a boost in the last two miles of the marathon when it is too late for carbs to be absorbed in your intestines.
Avoiding Hyponatremia
If you run the marathon in more than 3 hours on a warm day and drink large amounts of plain water during the race, you are at risk of hyponatremia. This is a condition caused by unusually low sodium levels in your blood; a large proportion of your body fluid is replaced with water, thereby reducing your body’s sodium content. There is evidence that women have a moderately higher risk of developing hyponatremia than do men. The symptoms of hyponatremia include weakness, nausea, disorientation, bloating, dizziness, seizures, and coma. Hyponatremia typically occurs only toward the end of ultramarathons or Ironman triathlons, but it can occur in the marathon on warm days, especially for 4-hour-plus marathoners who consume only water. The simple way to avoid hyponatremia during a hot-weather marathon is to consume fluids containing at least 250 milligrams of sodium per liter and to not drink more than you have lost as sweat.
How to Drink on the Run
The race nutrition plan described above assumes you’re regularly taking in a good amount of fluid, as opposed to most of it spilling down your front. Practice drinking while running at close to marathon race pace until you get good at it. It makes sense to slow a bit at the aid stations, but if you’re competitive, you won’t want to lose time to the runners around you. By practicing drinking on the run, you can greatly improve your proficiency at this skill.
If you’re an elite runner, you can usually arrange to have squeeze bottles at the aid stations along the course. This is optimal but obviously not readily available to everyone. Non-elites can help themselves by choosing marathons where friends or family members can meet them regularly along the way and give them bottles. Still, the majority of marathoners must master the paper cup.
A convenient way to practice drinking from cups is the round-and-round-the-track method—simply set up some cups at the local track and practice drinking every couple of laps. The advantage of the track is convenience. The disadvantage is that, if you’re running intervals, you’ll be breathing so hard that you’ll get to experience the dubious thrill of getting water up your nose. This approach works really well during a tempo run. If you do a 20- to 30-minute tempo run on the track and take a drink every two to three laps, you will quickly improve your drinking-while-running technique.
Another convenient way to practice drinking on the run is the road-loop method. Back your car to the end of the driveway, put a few cups of the beverage you’ll drink during the marathon on the back of your car, and head out for a repetitive loop run, grabbing a cup every time you pass your car.
Race-Day Technique
If volunteers are handing out fluids during the race, try to make eye contact with one and point at the cup so that you don’t surprise him or her. (If the cups are on a table, eye contact with the cup generally won’t help.) If volunteers are offering both water and a sports drink, begin yelling your preference as you approach the aid station so that the right volunteer hands you a cup.
Slow slightly and try to move your arm back while you grab the cup so that you don’t hit the cup with your full running speed. Squeeze the top of the cup closed so that all of the liquid
doesn’t slosh out, and take a swig. This will help prevent fluid from going up your nose when you tip the cup up to drink. The trick is to breathe normally. Always take a couple of normal breaths between swigs. When you’re done drinking, accelerate back to race pace.
Unless you’re an elite marathoner, the best strategy on a warm and humid day may be to stop and drink at the aid stations. Marathons typically offer aid stations every two miles to 5 kilometers, although some larger races have stops every mile. Let’s say that, from the start, you stop to drink every 2 miles. That’s 12 stops between the start and finish. If you spend 10 seconds drinking at each stop, you’ll add 2 minutes to your time. If you run through the stops while drinking, you’ll slow a little anyway, so stopping isn’t going to add much time, and stopping helps ensure that you take in enough fluid to fight off dehydration. On a warm day, an extra 2 minutes at the water stations can repay you with 10 to 20 minutes gained by the finish of the marathon.
What and when you eat and drink play an important role in how you adapt to training for a marathon. As we’ve seen, neglecting proper nutrition and hydration will mean not reaping the full benefits of your hard work. The same is true for not paying attention to easy days and other aspects of managing recovery from taxing training. Let’s look at what to do to maximize your chance of marathon success during the many hours each week when you’re not running long or hard.