born, and although she can no longer be an elite competitor. She is admired for her history of creating opportunity for women; but she is arole model nowas ahigh-profile 51-year-old who keeps in shape by running four or five times a week through a frenetically busy and mobile schedule, who lays down her briefcase and microphone to run the race with other mid-pack women.

That counts more now than winning. Switzer says, “Their role models are no longer Joan BenoitSamuelson and Frank Shorter, even though their names will always be revered. Now they look to Oprah Winfrey and Al Gore—famous and incredibly busy people who still made the time to train for a marathon, and completed it. The finish line doesn’t matter. It’s a case of ‘If Oprah can do it, I can do it. If fitness mattered that much to her, it should matter for me.’”

So for this new generation, which includes all age groups, the emphasis is on participation, not on pushing through personal records in a competitive career. That’s why the distances in the Global Women’s Circuit have to be attainable. Avon has a 10K run and 5K walk at each event, not marathons anymore. They provide advice on the very beginner’s basics of exercise: shoes, nutrition, sleep, organizing your time, how to begin, and above all answering the question “Why do it?”

Twenty years ago, women’s running was a movement of women catching up with men, about being

combative. Now it’s part of a rise in consciousness about health and lifestyle, among both women and men. And women are leading it.

I didn’t only swan about Avon and blob out in front of the World Cup. I worked with circuit announcer Sharon Barbano to identify and call the names of as many finishers as we could (never as simple as it might seem).

Baltimore winner Alicia Harvey had an international career as a track runner (as Alicia Hill), but what mattered more was her combination of lissome fitness with graciousness and warmth. It was the fit woman, again, they applauded, more than the winning athlete.

There was equal acclamation for other finishers—for 80-year-old Hedy Marque (whose time of 62:53 is remarkable by any standard), and for the many Avon sales representatives who walked and ran. One of the best receptions was for Avon’s Director of Sports Marketing, Carolyn Aishton, another busy and fit woman, who ran the full 10K, rather as if Juan Antonio Samaranch should finish the Olympic Marathon.

So Sharon and I peered through binoculars at flapping numbers and fumbled through lists on elusive curling sheets of paper, and called the names. It matters. That public moment—your name announced or in print, the finish-line photo, the few seconds when a crowd is cheering for you—is one big reason why many of us run races instead of jogging another day in solitude round our subNovember/December 1998

urb. There is nothing vainglorious or unusual about that. Humans are social animals, and to win a place in the consciousness of others gives meaning to any activity. That applies to music, religious worship, study, playing football, or cooking. On which thought I left Switzer to her fans and went off to have breakfast and watch Italy vs. Norway.

TORONTO, CANADA, July 5, 1998—The same was trueas we called another 1,000 women across the finish line in Toronto a week later, despite the cultural differences those few hundred miles bring.

The Canada stop on the Avon Global Circuit was just as impeccably efficient and professional as Baltimore was in its operation and presentation. There was music, a bagpiper to lead the runners to the start, a professional broadcaster (Paul Kennedy) and a top marathoner (Olympian Peter Fonseca) as announcers, rousing speeches, start-line aerobics. Yet by comparison with Baltimore it was all—in a word—quieter.

I might even risk saying more “British.” Instead of zestfully swirling in red ripples around the whole start area, here the runners waited in quiet clusters inside Commerce Court. They trickled out after the bagpiper as if they had not quite noticed him. Their aerobic stretches were whoopfree. I’m familiar with these cultural differences in my international travels on the road of running. A month earlier I was an announcer at a top

New Zealand event, the Christchurch Marathon. Try getting low-key Kiwis to do aerobics or go whoop. They even stay taciturn doing bungee jumps.

As so often, in Toronto the course gave character to the race. Baltimore had taken the runners through a key moment of American history with the loop through Fort McHenry. The Toronto course toured the downtown in a way you could never do with traffic on the streets. From Wellington Street, across Yonge, down to the Harborfront (world famous for its literary festival), past the Archway of the Great Expo, and back up to Wellington—a big circle, in effect, around Toronto Tower. No Canadian could ask for a more privileged route. I sometimes wonder if runners know how many thousands of hours have to go into negotiations and planning to secure such a course.

The way around it was led by Elizabeth Carmichael of North York, winning her second 10K of the weekend in a commanding 35:55. Even at this late date in the history of women’s running it’s worth pausing over that word “commanding,” and the case for women-only races. Sometimes it is seen as reverse discrimination. But the reality is that Elizabeth Carmichael’s race could never have been called commanding if she had run it surrounded by minor male runners. For all the emphasis on lifestyle and health, Avon still aspires to create incentive and give support for rising competitors. Every local winner (and masters winner and first Avon repreNovember/December 1998

sentative) are funded to go to the National Championship—this year on November 8 in Chicago.

Since all the Avon races are women-only, every winner has had to take the burden of being in front, of tactics and breaking and leading, of being 1“ overall, not 21“ among men. To win as along-distance runner, you have to know how to be lonely. And how to be commanding. Those are not easy responsibilities, but they go along with the opportunity to compete.

Recently in a collection of old posters, I came across one for a rural sports festival in Wiltshire, England, in 1826. There were two events for women: “Girls running for smocks” and “Old women running for a pound of tea.” They are advertised alongside “Hunting a pig with a soaped tail” and “Jumping in sacks for a cheese.”

Another poster, from Alton, Hampshire, in 1835, advertised the “women’s smock race” as the intermission entertainment during a program of horse races, a glimpse of ankles, I suppose, to provide relief from the serious sport of horses.

So things do change. In 1998 big races around the world are reporting that their women’s entries are steadily overtaking the men’s. The recent Rock ’n’ Roll Marathon was one of the first megaraces where women were in the majority. The Avon circuit looks to be riding or creating a new wave, a health and fitness message taking running deeper into society than ever before.

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In 1989, two runners set off to become the first to run from Death Valley to Mt. Whitney and back— in mid-summer. Lottsa luck, fellers!

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SPECIAL SPORTS MEDICINE SECTION

Is a Heart Rate ‘Monitor Worth It?

A First-Ever International Conference of Coaches and Scientists Addresses Heart Rate and Exercise and Ways to Use Heart Rate Monitors to Their Full Potential.

HESE DAYS it’s pretty common to see runners wearing a heart rate

monitor (HRM) while they train and race. Pick up almost any health and fitness magazine and you ll find articles and advertisements on heart rate monitors. These fancy little devices have “captured the hearts” of people around the world. More importantly, heart rate monitors have survived the “honeymoon” period that so many other training aids and nutritional gimmicks have failed to pass. The fact that heart rate monitors have endured the test of time suggests that they have been warmly accepted by people who use them.

HEART RATE MONITOR HISTORY

Heart rate monitors, as we know them today, have been on the market for 15 years. The Sport Tester PE2000, produced by the Polar Electro company in Finland in 1983, was the first wireless heart rate monitor and consisted of a transmitter strap worn around the chest and a receiver worn on the wrist. The transmitter sent a signal to the receiver, coinciding with each heart beat. The signal was processed, converted to a heart rate in beats per minute, and displayed on the monitor worn on the wrist. Early validation studies showed that heart rate measured with these wireless heart rate monitors was very similar to heart rate measured with an electrocardiogram (ECG). This was considered breakthrough technology because it allowed heart rate to be measured under free living conditions, with relatively inexpensive equip-

ment. It created wonderful opportunities for athletes who wanted to monitor their performances in a systematic way.

The following year Polar Electro produced the Sport Tester PE3000, a unique model that was designed to store heart rate, which could be transferred to a computer at a later stage for detailed analysis. This model represented another big step forward in technology and immediately caught the attention of scientists and serious athletes. Scientists could measure heart rate under free living conditions in their experiments and analyze the data later, and serious athletes could analyze their training intensity after the training session.

The next 10 years saw heart rate monitor features become more sophisticated while the memory capacity of the monitors also increased. The latest models of heart rate monitors, for example, are able to store heart rate data for up to 134 hours (Polar NV Vantage).

APPLICATION LAGS BEHIND THE TECHNOLOGY

However, the increasing sophistication of the technology and the memory capacity of heart rate monitors soon exposed the lack of knowledge and understanding that scientists, coaches, and athletes had to interpret the heart rate measurements. While the electrical engineers involved in developing heart rate monitors had excelled, the exercise physiologists were lagging behind in their understanding of the relationship between heart rate and exercise intensity. As a first step to bridging this gap in knowledge, in December 1997 a first-ever “International Conference on Heart Rate Monitoring and Exercise” was organized at the Sports Science Institute of South Africa. Scientists and coaches from around the world met to further their understanding of heart rate and exercise, with the overall goal of discussing ways of using heart rate monitors to their full potential. We discussed the following points relevant to endurance running.

Heart Rate and Exercise Intensity

Heart rate can be used as a measure of exercise intensity. This is based on the understanding that there are linear relationships between heart rate, workload, and oxygen consumption. We must not forget, however, that the leg muscles are the structures in the body that determine the running speed and the rate of fatigue after running for a long time. Under most circumstances the harder the muscles work, the faster the heart beats. In a sense, the muscles of the legs drive the heart. This explains why there is generally a linear relationship between running speed and heart rate. But this relationship between running speed and heart rate can be affected by a number of factors, which, therefore, may affect

the interpretation of heart rate data. For example, the day-to-day variation in submaximal heart rate is about six beats per minute. In other words, heart rate measured in a runner under identical conditions at a fixed running speed may range between, for example, 130 and 136 beats per minute without any change in fitness. Obviously, this day-to-day variation needs to be considered when heart rate data are interpreted.

Other factors such as duration of exercise and cardiac drift, environmental conditions, competition, the time of day, and a runner’s state of training affect the heart rate/running speed relationship. The first step in using a heart rate monitor effectively is to understand how these factors affect the heart rate/ running speed relationship.

Exercise Duration and Cardiac Drift

Heart rate increases gradually as the duration of exercise increases. This is known as cardiac drift. The magnitude of the cardiac drift is large and can significantly influence the heart rate/running speed relationship. For example, Elske Schabort from the Sports Science Institute of South Africa showed that the average heart rate of eight subjects who ran a 60-minute time trial in the laboratory (20 degrees C and 5 percent relative humidity) increased from 158 beats per minute during the first five minutes of the test to 177 beats per minute at the end of the test. Increasing ambient temperature and humidity during exercise exacerbates the cardiac drift.

John Booth of Australia conducted an experiment in which runners ran on a treadmill at 14.5 kilometers per hour (9.01 mile/hour) in a warm laboratory (32 degrees C and 60 percent relative humidity). The heart rates of the runners increased from 168 beats per minute to 188 beats per minute after 30 minutes. The body mass of the runners in the study also decreased 1 to 2 kilograms (2.2 to 4.4 pounds). The 20-beats-per-minute increase in heart rate of these runners, which may have been related to fluid loss, can perhaps be explained by the study from Austin, Texas. These scientists showed that for every | percent loss in body weight due to dehydration, heart rate increased by about 7 beats per minute. Their results also showed that adequate fluid replacement during exercise reduced the cardiac drift considerably. Table 1 shows the magnitude of heart rate increase after fluid loss and can be used as a guide for adjusting heart rate during exercise.

Environmental Conditions

Training and racing occurs in diverse environmental conditions. Many of the longer ultra races start in the early morning. By midrace the temperature can easily have increased by 10 degrees C. Anincrease in temperature of 10 degrees

TABLE 1 HEART RATE INCREASE AFTER FLUID Loss FOR RUNNERS OF DIFFERENT WEIGHTS

C may cause heart rate to increase by 10 beats per minute. This increase in heart rate as a result of increasing ambient temperature, coupled with the increase in heart rate as a result of dehydration and cardiac drift, can obviously alter the heart rate/running speed relationship quite significantly.

Competition

Competition is another factor that affects the heart rate/running speed relationship. In 1994 the second-placed finisher in the 90K Comrades Marathon claimed that he had under-performed in the race because he had adjusted his running pace according to a predetermined heart rate. After the race he believed the “heart rate-assisted pacing strategy” he adopted had caused him to run slower than he would have run had he paced himself without a heart rate monitor.

There are three possible outcomes from this example. Perhaps the runner ran to his full potential and with that pacing strategy did the best he could ever have done. Perhaps he would have won the race had he run at a faster pace earlier in the race, or perhaps he would have finished poorly had he run faster in the early stages of the race. Unfortunately, at present we do not know the answers to any of these questions.

The following year we conducted an experiment on running intensity during races and found by chance that runners’ heart rates during 10K and 21K races were higher than their heart rates at similar running speeds during noncompetitive training. We studied this phenomenon of a competitive-induced increase in heart rate further when we monitored the heart rate of an elite longdistance runner for five months during which time he participated in nine races over varying race distances (5K to 28K) on both the road and track. We found that during the competitive races there was absolutely no relationship between his heart rate and his running speed. For example, when he raced at 2:57 per kilometer (4:43 per mile), his heart rate varied from 148 to193 beats per minute.

Michael Lambert IS A HEART RATE MONITOR WORTH IT? 13

This finding has important implications for runners using heart rate monitors during competition as a gauge of their running pace: should your racing target heart rate be calculated on a heart rate determined during training, it would result in your running slower than expected during the race—exactly what the second-place Comrades runner claimed had happened to him.

Time of Day

The time of day during which training is carried out is another factor that can effect the heart rate/running speed relationship. A study has shown that the peak resting and exercising heart rate occurs at mid-to-late afternoon, and the lowest heart rate values occur in the early morning. The difference between the heart rate measured in the morning and mid-afternoon may be as muchas 10 beats per minute, which exceeds the day-to-day variation of heart rate under controlled conditions. It is clear, therefore, that the time of day should be considered when heart rate is used during fitness testing or as a marker of exercise intensity.

State of Training and Heart Rate

Most of the scientific studies on heart rate and exercise training have been conducted on unfit subjects who underwent exercise training as part of the study. The results in these studies are varied, ranging from no change to a decrease in heart rate of up to 10 beats minute at a fixed running speed.

The research data on changes in heart rate with training in already highly trained individuals is scarce. We studied a top-class half-marathoner and found that when his half-marathon (21.1K) race time improved from 64 to 62 minutes, his heart rate at 2:51 per kilometer pace (or 4:33 per mile pace) decreased from 164 to 160 beats per minute. This decrease in heart rate after training coinciding with improved running performance is within the day-to-day variation in heart rate. Collectively these studies show that the exercising heart rate of a sedentary person who trains and becomes fitter will be reduced and easily measurable. The same cannot be said for highly trained runners who might only have a marginal decrease in heart rate with improved running performance.

New Features—Heart Rate Variability

Another innovative feature of heart rate monitors is that the newer models (Polar’s NV Vantage, for example) are able to measure and store heart rate variability. A measure of heart rate variability can give some information about the underlying controlling factors that increase or decrease heart rate. This measurement offers great potential as a marker of one’s state of training and

more particularly as a predictor of the onset of overtraining as the control of heart rate changes under these conditions.

WHERE ARE WE NOW?

What are the relevant research questions that will improve the use of heart rate monitors? The concluding summary at the first “International Conference on Heart Rate Monitoring and Exercise” acknowledged that while it is generally accepted that heart rate monitors accurately measure heart rate under a variety of free living conditions, there is less agreement on how these heart rate data may be interpreted and used to optimize exercise prescription for health or performance. The following questions, which are relevant to long-distance running, arose from the conference and need to be answered before we can claim that heart rate monitors are being used to their full potential.

1, What heart rate training prescription produces optimum athletic performance? In other words, is it better to conduct long training runs at 70 percent of maximum heart rate or 75 percent of maximum heart rate? Or should runners start the training run at 70 percent of maximum heart rate and increase it to 75 percent as the run progresses? The answers to these questions are not presently found in the scientific literature, and coaches and athletes who use heart rate as a training aid do so merely on their own personal experience. Some probably get the formula right, others probably do not.

2. Do athletes who use heart rate monitors in training and racing perform better than those athletes who do not? This is the million dollar question! At this stage it cannot be proved that running performance is enhanced through the proper use of a heart rate monitor, although one can create a strong argument as to why athletes who use heart rate monitors have an advantage over athletes who do not. Should it ever be proved that heart rate monitors, if used properly, offer some advantage to athletes it will raise interesting questions about whether or not heart rate monitors can be used in competition.

3. Can heart rate monitoring be used to detect the early onset of overtraining? The biggest challenge for high-performance athletes is to get the balance correct between training too little or training too much. Although some researchers have monitored runners’ heart rate during sleep as a way of predicting the onset of overtraining, the greatest potential for monitoring overtraining symptoms lies in measuring heart rate variability as discussed earlier.

=) Michael Lambert IS A HEART RATE MONITOR WORTH IT? 15

IS A HEART RATE MONITOR WORTH IT?

How can you use your heart rate monitor to optimize your long distance training and racing performance? The first step in using a heart rate monitor effectively is to understand that the heart rate/running speed relationship, although generally linear, can be affected by a number of factors. Having said that, training intensity can be prescribed for a runner based on a certain heart rate. This approach has been described in many articles written for coaches and runners and does have potential for being a precise way to regulate running intensity in training, particularly for novice runners. However, at present there are no scientific data to support an ideal specific heart rate for different types of training, and much of what is written is based on anecdotal experiences. There is no doubt that future studies will refine this area, making the prescription of training heart rate a more exact science. Asa starter, however, the advice offered by Pete Pfitzinger is as good as any. It is described in Table 2.

As discussed previously, heart rate during competition is not an accurate marker of exercise intensity and therefore cannot be used as a sensitive gauge of running speed during competition. However, when we understand better the factors causing the elevated heart rate so that we can “correct” the heart rate/ running speed relationship, determined under noncompetitive conditions, then it may be possible for runners to use heart rate during competition to assist their judgement of running pace. This area needs to be addressed in future studies. The prudent advice at present, then, is to pace running speed during races according to perceived effort.

As explained earlier, the heart rate is an imperfect marker of exercise intensity. However, if we can control the factors that affect heart rate, then the heart rate/running speed relationship is fairly constant with a day-to-day variation of up to six beats per minute at any submaximal speed. The fairly constant heart

TABLE 2. TRAINING INTENSITY BASED ON HEART RATE

rate/running speed relationship under controlled conditions can be used to assess a runner’s state of training. But, as the changes in heart rate after training are likely to be rather small, hovering on the upper limit for day-to-day variation in heart rate, it is important to monitor trends in heart rate over time, rather than place too much emphasis ona single measurement. In other words, runners who use heart rate monitors need to become proficient at recording details of training so that trends in changes in their heart rate become apparent.

To facilitate this process of record keeping, at the start of a season or training cycle, a runner must determine the relationship between running speed (ranging from a slow training speed to a 10K racing speed) and heart rate. A runner can easily do this on a track according to the procedure described by Selley et al, (1995). The procedure requires that you run a series of 1000m repeats on a 400m track. The pace for each kilometer repeat is kept constant. Run the first kilometer about 20 seconds per kilometer slower than your current 5K time. After a 2-minute rest, run the next kilometer 10 seconds faster. Repeat this pattern of 1000m followed by a 2-minute rest period until you have completed about 6K. Record your heart rate throughout the test. After the test, plot your average heart rate for the last 60 seconds of each kilometer against the average running speed for that kilometer. This test can be done more accurately if you use a heart rate monitor that stores the heart rate until after the test and if a helper assists with pacing. The relationship between your heart rate/running speed should resemble a straight line and should be fairly reproducible from day to day, providing the conditions during the test are the same. This relationship between heart rate/running speed should represent the standard baseline assessment.

Previous studies have shown that the relationship between heart rate and running speed is almost linear between about 40 and 95 percent of maximum heart rate. After this standard baseline assessment, the relationship between a runner’s heart rate/running speed needs to be performed regularly, and can even be done on a daily basis during training runs. The test can be structured into the beginning phase of the training session. The runner needs to wear a heart rate monitor that has the capacity to store heart rate. The athlete should run over a marked, calibrated distance (about 1K) on flat terrain, protected from the wind. This test should be performed after the runner has fully warmed up and reached a steady-state. Running speed does not have to be the same for each test, providing the running time for the known distance is recorded. After the training session the athlete’s running speed over the calibrated distance can be calculated and plotted on a graph against the average heart rate for that section of the training run. This graph can easily be compiled; calculating each data point should take less than a minute. In simple terms, a data point lying below the standard line of heart rate/running speed suggests that the runner was “more

Figure 1 The linear relationship between heart rate and running speed. A data point lying above the line of best fit represents a “less efficient” state, and a data point below the line represents a “more efficient” state. The details of the next training session can be adjusted based on the location of the data 230 240 250 260 270 280

point. Running speed (meters per min)

“less efficient”

“more efficient”

Heart rate (beats per min)

efficient” for that training session, in contrast to a data point lying above the line, which indicates “less efficiency” for that training session (see Figure 1). It may be speculated that “more efficient” is compatible with a better state of fitness than the “less efficient” state. The coach/runner can make decisions about the next training session based on the location of the data point (i.e., whether the data point lies above or below the standard line of heart rate versus running speed).

CONCLUSION

Heart rate monitors measure heart rate very accurately. However, the interpretation of these measurements is lacking. At present heart rate monitors can be used as a guide of exercise intensity providing that we can control those factors that effect the heart rate/running speed. At present heart rate monitors should be used with caution in races, as the heart rate is higher at any running speed compared to training.

It is tempting to speculate that in the future, as more knowledge becomes available, heart rate monitors will be used to a greater potential in training and racing, making them true “ergogenic” aids. Then runners who use heart ‘ rate monitors in training and racing will have a clear advantage over . runners who do not.

REFERENCES

Selley, E.A., Kolbe, T., Van Zyl, C. G., Noakes, T. D., and Lambert, M. I. 1995. Running intensity as determined by heart rate is the same in fast and slow runners in both the 10- and 21-km races. Journal of Sport Sciences, 13, 405-410.

SPECIAL SPORTS MEDICINE SECTION

The Ergogenic Answer

The Key to Improved Performance Is Better Energy Use. But There Are Few Shortcuts.

H OW CAN I improve my performance times? This is the ultimate question all endurance athletes ask themselves—whether they are Olympic contenders or back-of-the-packers simply attempting to set a PR.

Energy is the key to endurance, and the inability to optimize energy use during sport competition leads to premature fatigue. To understand how to become faster, you need to know what limits energy production, control, and efficiency during endurance events.

¢ Physical power, or the ability of your muscles to produce energy, is limited by your physiological traits. In essence, energy production for aerobic endurance exercise is dependent primarily on the capacity of your heart, lungs, blood, and muscles to consume and use oxygen.

Mental strength, or the ability of your nervous system to control energy production, is limited by your psychological attributes. Energy control for endurance performance may be contingent on your brain’s capability to prevent mental fatigue during very prolonged competition. Mechanical edge, or the ability of your body to use energy efficiently, is limited by your biomechanical traits. Energy efficiency may be influenced by your specific neuromuscular skills and your body mass and composition.

While the specific physiological, psychological, and biomechanical traits that you inherit from your parents establish the upper limits of your endurance capacity, optimal training is necessary to maximize your genetic potential. Although appropriate training is the best way to improve endurance performance, in attempts to go beyond training, many athletes turn to ergogenic aids, which may be defined as any substance or method designed to provide an athlete with a competitive advantage, possibly by augmenting his or her physical power, mental strength, or mechanical edge.

Melvin H. Williams THE ERGOGENIC ANSWER m 19

SOME HISTORY ON ERGOGENIC AIDS

Throughout history endurance athletes have used countless ergogenic aids in attempts to enhance performance. For example, blood doping was popular in the early 1970s, and, most recently, recombinant erythropoietin (rEPO, a hormone drug) has been used effectively to increase red blood cells, maximum oxygen uptake, and endurance performance. However, because such practices may provide an unfair advantage and cause adverse health effects, including death, the International Olympic Committee (IOC) has prohibited the use of such ergogenic drugs, hormones, and methods. Thus, athletes continue their search for effective, yet safe and legal, ergogenic aids—mainly nutrients and various dietary supplements.

The six major classes of nutrients in the foods we eat—carbohydrate, fat, protein, vitamins, minerals, and water—contain over 40 essential nutrients that are involved in human energy processes in one way or another. We may also consume other products that may influence energy processes during exercise, including food drugs and dietary supplements. Table 1 lists some nutritional substances that have been theorized to be ergogenic for endurance athletes. Although nutritional ergogenic aids may be used in attempts to enhance mental strength or provide a mechanical edge, this brief review will focus on several of those that have been used by endurance athletes in attempts to increase physical power.

FACTORS LIMITING PHYSICAL POWER

Your car gets its power for high speeds from the oxidation of gas in its engine. Your muscles get their physical power for high-intensity aerobic endurance exercise, such as running a marathon, from the oxidation of carbohydrate, the primary fuel, and fats, a secondary fuel.

One limiting factor to physical power is the ability of your muscles to metabolize appropriate fuels. ATP (adenosinetriphosphate), a high-energy compound, is the only immediate source of energy for all muscle contraction, but muscle ATP supplies are very limited, only lasting a second or so. To sustain high-intensity aerobic exercise, the body needs to replenish its ATP supplies, and the primary means to regenerate ATP rapidly during such endurance events is oxidizing muscle fuels, primarily carbohydrates and fats.

Although proper training will increase the capacity of your muscles to metabolize both carbohydrate and fat, athletes also use various nutritional ergogenics in attempts to optimize fuel usage for improved performance.

Another factor that limits physical power in endurance exercise is your ability to supply and use oxygen. Oxygen supply depends on the ability of your

TABLE 1 NUTRITIONAL SUBSTANCES THEORIZED TO BE ERGOGENIC FOR ENDURANCE ATHLETES

heart, lungs, and blood (cardiovascular-respiratory system) to transport oxygen to your muscles, while oxygen use is dependent on metabolic processes within your muscles. Again, proper training will increase the capacity of your cardiovascular-respiratory system to deliver oxygen and your muscular system to use it, but athletes are also using various nutritional ergogenics in attempts to augment this training effect.

NUTRITIONAL ERGOGENIC AIDS TO ENHANCE FUEL UTILIZATION

The foods we eat provide us not only with energy nutrients, but also with nutrients needed to release this energy during exercise. Nutritional ergogenics

Melvin H. Williams THE ERGOGENIC ANSWER 21

have been used in attempts to augment premium fuel sources or to exert favorable effects on muscle fuel metabolism during exercise.

Carbohydrate

Carbohydrate is a more efficient fuel than fat, requiring less oxygen to produce ATP. Carbohydrate gives you more miles per gallon, so to speak. Almost all of your dietary carbohydrate, such as bread, cereal, pasta, and fruits, is converted in the body to glucose. Glucose is the carbohydrate form that provides energy needed to form ATP. Excess glucose is stored as glycogen in the liver and muscles.

During exercise, muscle glycogen can break down to glucose for oxidation and subsequent ATP production directly in the muscle, while the liver can release glucose to the blood for delivery to the muscle.

However, muscle and liver glycogen stores are limited, and may become suboptimal within 90 minutes of high-intensity aerobic exercise. Therefore, carbohydrate supplementation may be ergogenic in two ways: increasing your initial fuel stores and refueling as you go.

Carbohydrate-loading (technically called muscle glycogen supercompensation) is designed to increase muscle and liver glycogen stores, possibly 50 to 100 percent or more, prior to exercise. During the tapering week prior to the competitive event, athletes may consume 400 to 600 grams of carbohydrate for several days. In a recent review, John Hawley and his associates from the prestigious Sports Science Institute of South Africa indicated that carbohydrate-loading procedures may elevate muscle and liver glycogen stores, postponing fatigue and improving performance by 2 to 3 percent in endurance events where a set distance (such as a marathon) is covered as quickly as possible. Also, carbohydrate consumption during prolonged exercise is designed to provide additional glucose to the muscle. The optimal amount appears to be about 30 to 60 grams of carbohydrate per hour, an amount provided by consuming 4 to 8 ounces of a typical sports drink, such as Gatorade, every 15 minutes. Numerous studies worldwide have shown that ingesting either solid or liquid carbohydrate during endurance exercise enhances performance.

Carbohydrate By-Products

In the aerobic process of producing ATP, glucose is converted to over 20 metabolic by-products, or metabolites. Several of these by-products have been suggested to be more ergogenic than typical glucose supplements. In a recent review, John Ivy from the University of Texas suggested that supplementation with pyruvate and dihydroxyacetone phosphate (DHAP) could enhance endurance performance in untrained males, possibly by increasing muscle glucose uptake or sparing muscle glycogen. However, all human studies finding an ergogenic effect of DHAP were conducted in the same research facility, so confirming data are needed from other laboratories. Moreover, Ivy also indicated that the effect of DHAP supplementation on trained subjects is unknown.

Research with other glucose metabolites, such as fructose 1,6-diphosphate, and lactate salts (polylactate), has not shown any ergogenic effect beyond that provided by glucose.

Fat-Loading

Our major dietary lipid is fat, which is stored in the body mainly as triglycerides in adipose and muscle tissues. The triglycerides may be catabolized to free fatty acids (FFA), and the FFA are eventually oxidized to produce ATP. Muscle triglycerides provide FFA directly in the muscle, while FFA from the adipose tissue must be mobilized and delivered to the muscle via the blood. Although FFAare an important fuel source for aerobic endurance, they are not as efficient as carbohydrate. Fat use predominates in low- to moderate-intensity aerobic exercise, whereas carbohydrate use predominates in high-intensity aerobic exercise.

Your body supply of fat, and thus triglycerides, to support the energy needs of exercise is almost limitless. So why would you want to supplement your diet with fat to increase your endurance?

Most dietary strategies or supplements attempt to increase FFA oxidation and reduce reliance on your limited carbohydrate stores, sparing muscle glycogen for use during the latter stages of an endurance event.

Because ATP production from fat oxidation is less efficient than carbohydrate oxidation, you would have to slow down your pace if you were low in glycogen and dependent primarily on fat. Sparing muscle glycogen early in the race may help you maintain a faster pace during the latter part.

Fat-loading is a dietary strategy in which you adopt a high-fat, low-carbohydrate diet for several weeks in attempts to shift energy metabolism during exercise to fat instead of carbohydrate. Although several preliminary studies have shown some beneficial effects of fat-loading, most benefits were observed in low- to moderate-intensity, not high-intensity aerobic endurance exercise. A recent review concluded that although the fat-loading hypothesis is intriguing, the current scientific literature is not supportive.

Medium-Chain Triglycerides (MCT)

Most dietary fat we eat is digested and metabolized rather slowly. Mediumchain triglycerides (MCT) are oral water soluble supplements that may enter

the circulation more readily than normal dietary fats and move into the muscle cell mitochondria for oxidation more readily as well.

MCT have been theorized to be a more efficient lipid energy source during exercise. However, recent research has shown that oral MCT do not make any significant contribution to energy metabolism during exercise and actually impaired performance in high-intensity 40K cycling tasks. Oral MCT supplements cannot be recommended at this time.

On the other hand, Lambert and her colleagues from the Sports Science Institute of South Africa indicated that adaptation to a high-fat diet for 10 days, combined with carbohydrate and medium-chain triglyceride (MCT) intake during exercise, could enhance performance in high-intensity exercise bouts. Their procedure involved ingesting 100 milliliters (about 3.3 fluid ounces) every 10 minutes of a solution containing about 2 grams of MCT per 100 milliliters for 60 to 90 minutes prior to exercise, while during exercise consuming the same solution but adding 10 grams of carbohydrate per 100 milliliters. This study suggests that the combination of fat-loading, along with MCT and carbohydrate intake during exercise, may enhance endurance performance. However, Lambert and her colleague recommended that athletes rehearse this strategy during training, as it may cause diarrhea in some individuals. More research is needed to support this preliminary finding.

Caffeine

The drug caffeine, a potent stimulant, is found naturally in certain foods and beverages. For example, one cup of drip coffee contains about 100 to 150 milligrams of caffeine, a therapeutic dose. Caffeine may benefit performance in several ways, and for years it has been a favorite ergogenic aid for endurance athletes.

Caffeine may benefit performance by stimulating neurological functions. For example, recent research has shown that cyclists exercising at a set level of psychological effort can produce more work in 10 minutes when given caffeine. Caffeine supplementation has been shown to improve performance in a 1,500m run, an event that may be benefited by psychological stimulation. Although a 1,500m run is an abbreviated endurance task, caffeine-stimulated improvements in training may lead to enhanced competitive performance.

Caffeine may also benefit metabolic functions during exercise, either directly or indirectly, by stimulating the release of epinephrine (adrenaline), a potent hormone. Many studies have shown that caffeine supplementation can improve performance in prolonged aerobic endurance tasks greater than one hour in duration. One theory suggests caffeine increases the use of FFA for energy, sparing muscle glycogen, but other unresolved mechanisms, including

psychological effects, may be responsible for this ergogenic effect.

The IOC has restricted, but not totally prohibited, the use of caffeine. However, legal doses are effective ergogenics. For example, 5 milligrams of caffeine per kilogram (2.3 milligrams per pound) of body weight, the amount of caffeine found in 3 to 4 cups of coffee or 2 Vivarin tablets, is legal and has been shown to be an effective ergogenic.

Carnitine

Carnitine, a vitamin-like compound, may influence energy metabolism in several ways. Of possible ergogenic value for the endurance athlete, carnitine facilitates the transport of fatty acids into the mitochondria for oxidation, a function that might spare the use of muscle glycogen during exercise.

However, there are no scientific data to support a muscle glycogen-sparing effect of carnitine supplementation. Moreover, three recent detailed reviews of the available scientific research concluded that carnitine supplementation does not affect metabolic processes during exercise, nor does it influence actual endurance performance in events such as a marathon or 20K run.

Creatine

Creatine, a substance found naturally in small amounts in animal foods, is currently the hottest-selling dietary supplement for athletes. Creatine supplementation can increase the muscle supply of creatine phosphate, a high-energy compound used in very-high-intensity exercise, such as sprinting. Although creatine is not marketed to endurance athletes, some research suggests it may influence endurance performance, both positively and negatively.

On the positive side, some research has shown improved performance in 300m and 1,000m repeat sprints. If creatine supplementation could increase interval training intensity, you could possibly improve your competitive performance. Well-controlled research is needed to evaluate the effect of chronic creatine supplementation on the training response and subsequent competitive endurance performance.

On the negative side, creatine supplementation has been reported to impair performance in a 6K (3.6-mile) terrain run. One consistent side effect of creatine supplementation is a rapid body weight increase, possibly several pounds ina week. This rapid weight increase is primarily water, a possible mechanical disadvantage to the runner who has to move the additional body weight.

For those who desire to experiment with creatine supplementation in training, a loading-maintenance protocol has been recommended. To load, consume 20 grams of creatine (four doses of five grams) daily for five days; to maintain, consume one five-gram dose daily for eight weeks.

NUTRITIONAL ERGOGENIC AIDS TO ENHANCE OXYGEN METABOLISM

Many nutrients are involved in the transportation and utilization of oxygen in the body. Nutritional ergogenics, including essential nutrients and commercial dietary supplements, have been used in attempts to increase oxygen delivery via the red blood cells or to facilitate oxygen use in the muscles.

Iron is essential for forming hemoglobin, the compound in the red blood cells (RBC) that transports oxygen to the muscles. Iron deficiency is the most common mineral deficiency among endurance athletes, particularly female athletes onlow-calorie diets. Curing an athlete’s iron-deficiency anemia with iron supplementation will increase oxygen uptake and return endurance performance to normal. However, iron supplementation in athletes with normal iron and hemoglobin status has not been shown to enhance performance.

The United States Olympic Committee recommends female athletes undergo blood testing periodically to determine hemoglobin status. If low, iron supplementation under the guidance of a health professional may be recommended.

Phosphorus

Phosphorus is an essential nutrient present in the diet as phosphate salts. Phosphate is part of 2,3-DPG, a compound associated with hemoglobin in the RBC to facilitate oxygen release. An increased 2,3-DPG level and oxygen uptake is the prevalent theory underlying phosphate supplementation to endurance athletes.

Four well-controlled studies have shown that phosphate supplementation (about four grams sodium phosphate per day for three to six days) may increase maximal oxygen uptake (VO,max) by about 10 percent. Several of these studies showed increased endurance performance as well. However, other studies have not shown any ergogenic effects, and a recent review by Mark Tremblay and his colleagues has recommended more research to resolve this issue.

Inosine

Inosine, a nonessential nutrient, is theorized to enhance endurance performance by increasing 2,3-DPG, aiding oxygen delivery to the muscles in a fashion similar to phosphate supplementation. However, two well-controlled studies found that inosine supplementation did not improve oxygen delivery during either submaximal or maximal exercise, nor did it improve performance

in athree-mile run. Moreover, both studies found that inosine supplementation actually impaired performance in maximal runs to exhaustion on a treadmill.

Glycerol

Glycerol (glycerin), an alcohol by-product of fat hydrolysis, may be converted to energy in the body, but has been studied as a potential ergogenic for other reasons. When consumed with water (about one gram glycerol diluted in 20 to 25 milliliters of water), glycerol exerts an osmotic effect that helps increase total body water, including an increased plasma volume in the blood—an effect that could increase oxygen delivery to the muscles.

Several studies have shown that glycerol supplementation may improve cycling endurance performance, but other research has shown that carbohydrate supplementation improved cycling endurance as well as glycerol supplementation. Additional research is needed to evaluate the ergogenic effect of glycerol supplementation, particularly in distance running in which the extra body mass (water weight) must be moved as efficiently as possible. Glycerol capsules and a glycerol-containing sports drink, with proper instructions for use, are marketed to endurance athletes.

Coenzyme Q10 (Ubiquinone)

Coenzyme Q10 (CoQ,,), a vitamin-like compound also called ubiquinone, is a dietary supplement targeted to endurance athletes. CoQ,, is essential for oxidative energy production in heart and skeletal tissue mitochondria. Theoretically, improved oxygen usage in the heart and skeletal muscles could improve aerobic endurance performance.

However, most studies have shown that CoQ, supplementation in healthy, physically active individuals did not influence physiological functions during exercise, like heart rate or VO,max, or cycling endurance performance. Actually, one study reported that CoQ, , supplementation was associated with muscle tissue damage and impaired cycling performance.

Ginseng

Ginseng comes in many forms, but Panax ginseng (Chinese or Korean) and Eleutherococcus senticosus (Siberian or Russian) have been most studied for their ergogenic potential. Although the ergogenic effect of ginseng has been attributed to plant extracts called ginsenosides, no actual mechanism has yet been identified. Nevertheless, some investigators hypothesize that ginsenosides may increase cardiovascular capacity during exercise.

Older studies have shown beneficial effects of ginseng supplementation on endurance performance. However, in a recent comprehensive review, Michael

Melvin H. Williams THE ERGOGENIC ANSWER @® 27

Bahrke and William Morgan noted that these early studies were characterized by numerous shortcomings and concluded that there is a lack of well-designed research supporting an ergogenic effect of ginseng supplementation. Recent well-controlled studies have not shown any ergogenic effect of either Chinese or Siberian ginseng on endurance performance in moderately- or highly-trained runners.

The informed consumer should be aware that the ginsenoside content of commercial ginseng products may vary widely, being nonexistent in some products. Also, some products contain ephedrine, an IOC-prohibited drug.

SUMMARY

As endurance athletes, the key nutritional principle for you to follow is to consume a varied, balanced diet of wholesome, natural foods among and within the various food groups. A diet rich in fruits, vegetables, whole grains, lean meats, and low-fat dairy products will provide adequate calories, carbohydrate, essential fats, protein, vitamins, and water.

As noted in this review, however, several nutritional strategies may enhance endurance performance but most do not, and some may even impair endurance performance. Some dietary supplements may also pose health risks. For example, some products may cause gastrointestinal distress and diarrhea. Using products containing drugs such as ephedrine has been associated with more severe consequences, including death.

Ideally, if you desire to use nutritional ergogenic aids, consult with a sports nutritionist or sports-oriented physician before experimenting with such products. If not, experiment with the supplement in practice before using it in competition, keeping track of your performance and any possible side effects.

The old adage, “Caveat emptor!” (Let the buyer beware!) is apropos when considering buying dietary supplements advertised to increase endur- g ance performance. Some work, but most do not. es

REFERENCES

Bahrke, M. and Morgan, W. 1994. Evaluation of the ergogenic properties of ginseng. Sports Medicine, 18, 229-248.

Graham, T. and Spriet, L. 1996. Caffeine and exercise performance. Sports Science Exchange, 9, (1), 1-5.

Hawley, J.A., Schabort, E. B., Noakes, T. D., and Dennis, S. C. 1997. Carbohydrate-loading and exercise performance. An update. Sports Medicine, 24, 73-81.

Heinonen, O. 1996. Carnitine and physical exercise. Sports Medicine, 22, 109-132.

Ivy, J. L. 1998. Effect of pyruvate and dihydroxyacetone on metabolism and aerobic endurance capacity. Medicine and Science in Sports and Exercise, 30, 837-843.

Lambert, E. V., Hawley, J. A., Goedecke, J., Noakes, T. D., and Dennis, S. C. 1997. Nutritional strategies for promoting fat utilization and delaying the onset of fatigue during prolonged exercise. Journal of Sports Sciences, 15, 315-324.

Montner, P., Stark, D. M., Riedesel, M. L., Murata, G., Robergs, R., Timms, M., and Chick, T. W. 1996. Pre-exercise glycerol hydration improves cycling endurance time. International Journal of Sports Medicine, 17, 27-33.

Tremblay, M. S., Galloway, S. D., and Sexsmith, J. R. 1994. Ergogenic effects of phosphate loading: Physiological fact or methodological fiction? Canadian Journal of Applied Physiology, 19, 1-11.

Williams, M. H. 1999. Nutrition for Health, Fitness, and Sports. Dubuque, [A: WCB/McGrawHill.

Williams, M. H., and Branch, J. D. 1998. Creatine supplementation and exercise performance: An update. Journal of the American College of Nutrition, 17 (3), 216-234.

Parts of this manuscript have been adapted from Williams, M.H. The Ergogenics Edge: Pushing the Limits of Sports Performance, Champaign, IL: Human Kinetics, 1998, and Will Nutritional Ergogenics and Sports Performance, President’s Council on Physical Fitness and Sports Research Digest, Series 3, No. 2, June, 1998.

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The Painful Heel

For Distance Runners, the Heel Can Be the Source of Misery. Don’t Let It.

HE FOOT is a complex anatomical structure requiring the coordinated

movement of 28 bones, 58 tendons, and 112 ligaments to function properly. Running places on each foot strike a force equal to three times your body’s weight.

Given the foot’s complex anatomy, it is no wonder so many runners experience foot pain and foot problems in the course of their training and racing. Because of the direct pressure the heel absorbs when it hits the ground and the biomechanical stress placed on it during the process of running, the heel region is one of the most frequently injured areas on a runner’s foot.

The heel bone (calcaneus) is the largest foot bone and is a connecting point for the plantar fascia, Achilles tendon, and several other muscles and ligaments. Additionally, various nerves surround the heel on both sides.

The forces acting negatively on the heel as aresult of direct trauma, overuse, or faulty biomechanics can lead to injury in one of the largest categories in the lexicon of running injuries, including but not limited to plantar fascitis (heel spur syndrome), heel bursitis, calcaneal (heel bone) stress fractures, nerve entrapments, retrocalcaneal bursitis, and insertional Achilles tendonitis. Let’s take a look at each injury.

PLANTAR FASCIITIS/HEEL SPUR SYNDROME

Plantar fasciitis may be the most common overuse foot injury encountered by distance runners. The plantar fascia is a thick fibrous band on the bottom of the foot that extends from the heel bone to the base of the toes (see Figure 1) and supports the longitudinal arch and aids in foot propulsion while you run. The plantar fascia is relatively inflexible, and when overstressed, it will pull on the heel bone, causing pain and inflammation, a condition knownas plantar fasciitis.

plantar fascia

Figure 1: Plantar fascia

Over time, the constant pulling of the fascia on the heel bone can cause a bone spur to form on the bottom of the heel (see Figure 2).

A heel spur alone is not usually painful, but it represents a chronic irritation at the junction of the fascia and the heel bone. Plantar fasciitis generally does not result from a single traumatic episode, but rather from repetitive stress placed on the bottom of the foot. The early symptoms of plantar fasciitis are often described as feeling like a stone bruise on the bottom of the heel. Initially, the pain from plantar fasciitis will occur when you take the first few steps after

Figure 2: Heel spur

getting out of bed in the morning or after sitting for a long time. As the fascia stretches slightly, the pain usually disappears, allowing you to train with little or no discomfort.

However, if left untreated, this injury will become more severe, and you will feel pain throughout the day, and running will be very difficult. Plantar fasciitis can result from overtraining, worn-out or inappropriate running shoes for your foot type, contact with hard running surfaces (such as concrete), or structural or biomechanical abnormalities affecting the foot and leg. These abnormalities include rigid, high-arched feet and overpronation.

Runners with rigid, high-arched feet probably make up less than five percent of the running population. This foot type has an arch that remains high when bearing weight and is often equated with the term “oversupination.” When having your arch height evaluated, make sure you are standing, as it is common for an arch that appears high when not bearing weight to flatten when weight is placed upon it. The structure of a rigid, high-arched foot makes it a poor shock absorber, which in turn increases the stress on the plantar fascia and, therefore, the potential for injury.

A much more common biomechanical fault that can cause plantar fasciitis is overpronation. Pronation is the normal foot motion that gives the appearance of the heel rolling inward and the arch flattening out. Pronation helps the body absorb the impact of the footstrike. Overpronation occurs when the foot rolls inward more than normal, effectively lowering the arch excessively and making the foot less stable. Any time the foot overpronates, the plantar fascia can become stretched at its origin, which may lead to plantar fasciitis.

Overpronation can result from inherited foot structure or from a runner compensating because of some biomechanical abnormality, including leg length differences, ligament laxity (hypermobility), and muscular imbalances.

One of the most common causes of overpronation in runners is tightness in the gastrocnemius and soleus (calf) muscles. When this muscle group lacks adequate flexibility, the upward motion of the ankle is restricted, which causes the foot to overpronate to make up for the lack of motion.

Treating Plantar Fasciitis/Heel Spur Syndrome

The first step in treating any overuse injury is to self-evaluate any factors that may have led to the injury. This evaluation may include a review of your current training mileage and intensity, shoe gear, training surfaces, flexibility, and other variables that may have contributed to your symptoms. By changing or modifying these factors as appropriate, you will reduce the likelihood of your injury becoming a lingering problem.

Specific treatment for plantar fasciitis/heel spur syndrome breaks down into two categories:

1. Pain reduction, and

2. Correction or control of the causative factors

You can reduce pain and inflammation by applying ice over the heel region for 15 minutes two to four times a day. This treatment has the advantage of providing both an anti-inflammatory effect and pain reduction directly to the heel with little risk of undesirable side effects.

Nonsteroidal anti-inflammatories such as ibuprofen can also alleviate discomfort; however, these pills do not “cure” plantar fasciitis, and in most cases they provide only temporary relief. Cortisone injections should not be a firstline treatment for plantar fasciitis, but it can be effective when chronic inflammation persists. In general, you should not have more than three cortisone injections in one localized area of the foot because of the effects cortisone can have on the surrounding tissue.

The most important aspect in treating plantar fasciitis/heel spur syndrome is to correct or control the biomechanical factors that may have led to the injury. Since the most common cause of plantar fasciitis is a repeated stretching of the fascia itself, treatment should be directed toward supporting the fascia and addressing any indirect causes that place undue stress on it. As mentioned previously, the most common cause of indirect stress on the plantar fascia comes from tightness in the calf muscle group. A tight gastrocnemius—soleus muscle group prevents the ankle from being able to bend sufficiently for normal motion to occur while you run. To make up for this lack of motion, the foot may overpronate and strain the fascia. Thus, an important component in the longterm management of plantar fasciitis is ensuring adequate flexibility in the calf muscle area.

There are many excellent stretches for the calf muscles; be sure to use good technique for the stretch you are performing and avoid overstretching. In some circumstances you may use a device called a dorsiflexion or night splint (see Figure 3), which keeps the foot ina 90-degree po- _ sition, stretching the calf Figure 3: Dorsiflexion splint

muscle while you sleep. Maintaining adequate calf flexibility is an integral component in the treatment and prevention of plantar fasciitis and other lower extremity overuse injuries.

Although the bottom of the heel is often the primary area of discomfort in plantar fasciitis, the actual mechanism of injury causing the pain is a stretching of the plantar fascia itself. For this reason heel cups or heel cushions seldom offer significant relief from this condition. The goal of treatment should be to provide support for the fascia to prevent it from pulling excessively.

Supporting the longitudinal arch can be accomplished by taping or padding, using over-the-counter arch supports, or custom-made, functional orthotics. Taping techniques that support the arch can help relieve stress on the plantar fascia. The disadvantages to this form of treatment are that you have to know how to tape the foot correctly and that the tape has to stay on the foot to be effective. Taping can sometimes result in blisters and skin irritation when used for an extended period. Over-the-counter arch supports will usually provide greater support for the foot than the sockliners typically found in running shoes. There are many kinds of these arch supports available from your local running store, and you should make sure they fit comfortably before you run in them. In general, avoid arch supports that are rigid, since they are not custom-molded to your foot and can create areas of irritation. If, despite these self-treatment methods, your heel pain persists, your sports medicine physician may recommend functional orthotics, which differ from arch supports. These orthotics require a mold of your foot and are designed not only to support the arch, but also to place the foot in a more biomechanically correct position, thereby controlling the forces contributing to plantar fasciitis (see Figure 4).

Functional orthotics should be considered after other forms of treatment have failed to alleviate your symptoms. In these resistant cases, biomechanical control of the foot can have a significant role in treating and preventing plantar fasciitis/heel spur syndrome. Almost all cases of plantar fasciitis/heel spur syndrome will improve or resolve with conservative treatment.

Heel Surgery

If your heel pain persists after you have exhausted these forms of treatment, surgery may be indicated. Traditionally, surgery for heel spur syndrome and plantar fasciitis required a large open incision to release the fascia from the bone and removal of the bone spur. However, since almost without exception the bone spur itself does not cause the pain associated with this injury, newer procedures have been developed that can release the fascia without significant trauma to the surrounding tissue.

One such procedure is endoscopic plantar fasciotomy (EPF),which uses a small camera called an endoscope that is inserted near the heel through two

Figure 4: The overpronated foot (left) controlled with an orthotic (right)

small incisions and allows the surgeon to visualize the fascia. The fascia is then partially released with a special instrument. The heel spur is not removed in this procedure.

Although recovery from EPF is less involved than undergoing open heel surgery, it will still take several weeks for full healing to take place. After a few days, however, you can return to activities such as pool running and bicycling to maintain aerobic fitness.

Although plantar fasciitis/heel spur syndrome is the most frequent cause of heel pain in distance runners, other conditions can also cause heel pain. Be aware of these other injuries to ensure that you are accurately diagnosed and that your treatment is specific to your particular problem.

Let’s look at other conditions affecting the heel, including heel bursitis, calcaneal stress fractures, nerve entrapments, and retrocalcaneal problems.

HEEL BURSITIS

neath the heel. However, with heel bursitis, the pain will usually persist with any weight-bearing activity, whereas with plantar fasciitis the sym-ptoms tend to diminish after the fascia “warms up.”

Treating heel bursitis usually includes replacing worn-out shoes, using a cushioned footbed in your running shoes (and dress shoes as appropriate), and icing the heel region to reduce inflammation. If these measures do not resolve the problem, your physician may recommend a cortisone injection into the bursa.

CALCANEAL STRESS FRACTURES

A stress fracture is a break in the bone as the result of repetitive, low-grade impact or trauma that eventually weakens the bone to the point of fracture. As mentioned earlier, while you run your heel bone is subject to a great deal of impact stress, often exceeding three times your bodyweight. Overtraining, worn-out running shoes, training on hard surfaces, and metabolic considerations such as eating disorders, menstrual irregularities in women, and decreased bone density can predispose a runner to a stress fracture.

Symptoms of a calcaneal stress fracture differ from plantar fasciitis in that the pain is usually present with all weight-bearing activities. There may be slight swelling, and there is often discomfort if you press the sides of the heel.

Because of the irregular shape of the heel bone, these injuries may be difficult to detect on normal X rays (see Figure 5), and a bone scan may be required to confirm if a stress fracture is present.

Figure 5: x ray showing a stress fracture of the heel

Once a stress fracture is diagnosed, treatment consists of stopping all weightbearing exercise for at least six weeks but could extend to six months. A cast is often not necessary, but you may need crutches for a few weeks if it is too painful for you to walk or stand.

Cross-training activities such as bicycling, pool running, and swimming are permissible while the injury is healing, but a premature return to running can result in prolonged healing and possible complications, including a complete fracture of the heel bone.

NERVE ENTRAPMENTS

Although uncommon, irritation to the nerves on the inside of the heel region can also result in heel pain. The most common nerves affected are the posterior tibial nerve on the side of the ankle or one of its branches, the medial calcaneal nerve. The tissue surrounding these nerves can become inflamed or the nerve itself entrapped as a result of tendonitis, varicose veins, or biomechanical factors such as overpronation. When the posterior tibial nerve is affected, the condition is known as tarsal tunnel syndrome. Symptoms of nerve-related problems may include numbness, a sensation of pins and needles known as parasthesias, or shooting pain in the heel, foot, or leg.

The diagnosis of a nerve injury may involve specialized tests such as nerve conduction velocities, electromyography, or magnetic resonance imaging (MRI). Treatment is often geared toward reducing the inflammation around the nerve and addressing the factors that may have contributed to the condition. As with other heel problems, surgery should be contemplated only as a last resort.

RETROCALCANEAL HEEL INJURIES

Heel pain occurring on the back of the heel is often due to injury to the Achilles tendon or its related structures. The Achilles tendon inserts into the posterior aspect of the heel. Underneath the tendon is a bursa called the retrocalcaneal bursa. Don’t confuse pain in this area with the pain of plantar fasciitis/heel spur syndrome. This injury is the result of Achilles irritation where the tendon inserts into the heel bone.

The treatment for pain in this region depends on whether there is calcification in the tendon, whether the tendon or retrocalcaneal bursa is inflamed, or whether there is a bony prominence contributing to the symptoms. These injuries tend to be slow to heal because of relatively poor circulation to this area.

MEDICAL HEEL PAIN

Although most heel pain in runners is related to overuse, abnormal biomechanical function, or impact-related causes, some heel pain can be due to diseases or problems that originate in other parts of the body. Medical conditions such as gout, diabetes, and certain types of arthritis can affect the heel before showing signs elsewhere in the body. When symptoms are not consistent with biomechanical heel pain, or when discomfort is not relieved by conservative treatment, your sports medicine physician may want to order additional tests to determine whether your heel pain is medically related.

PREVENTING HEEL PAIN

Distance running presents a unique biomechanical challenge that forces the lower extremity to absorb continuous repetitive impact of over three times our body weight, often for several hours at a time. Injuries to the foot, ankle, and leg are not uncommon in runners, and the heel region is one of the most frequent areas.

Common sense can often prevent many of these injuries from occurring. Following a realistic training program that allows for a gradual increase in distance and intensity can help your body adapt better to the increasing demands placed on it. Alternating your running surfaces and seeking out softer surfaces such as trails can reduce impact stress to the foot as can wearing appropriate running shoes for your foot type and replacing them before they are significantly worn out.

Maintaining adequate lower extremity flexibility can also reduce the chance of abnormal compensation taking place, which can contribute to overuse injuries. Be aware of biomechanical faults such as overpronation, leg length differences, and rigid high arches, and take steps to control these when appropriate.

Heel injuries can be challenging to resolve the longer they are left untreated. If self-evaluation and care does not provide relief, and your pain persists longer than seven days, gets worse, or reoccurs, get your heel evaluated by your sports medicine physician so you can learn what further forms of treatment are ‘ necessary to get you back on the roads and trails as quickly as possible. es

SPECIAL SPORTS MEDICINE SECTION

Too Darn Hot?

The Effect of Heat Stress on Marathon and Road Race Injury and Performance is Predictable. Knowing When It’s Too Hot for You to Run Could Save Your Life.

By WILLIAM O. ROBERTS, MD

\ ] EALL knowrunners who never miss a day out on the roads. Torrential

downpour, three feet of snow, fever, cold—it doesn’t matter. The Run or The Race rules. You may even be this runner. As much as you don’t want to hear it, there are days when you would be better off skipping your run—or cross-training or exercising indoors. A brutally hot and humid day may be one of those days. The effect of heat stress on marathon and road race injury and performance is predictable, and this article aims to make you a more informed competitor so you know your personal limits regarding heat stress and can answer the question, “When is it too hot for me to run safely?”

SOME BACKGROUND INFORMATION

Body heat is distributed in the core and shell of the body. The body shell is the surface for heat exchange and varies in “thickness” based on the need to lose or conserve heat. Cellular heat is accumulated during running along with a corresponding rise in body temperature. The rise in cell temperature in the essential organs causes the syndrome of exertional heat stroke (EHS).

Core temperature is a sum of exercise-produced metabolic heat plus environmental heat added to the body minus heat lost to the environment. Metabolic heat is a function of intensity and duration of exercise. Environmental heat is gained when the ambient air temperature is greater than skin temperature or from the sun’s radiant heat. Heat is lost from the body by evaporation, conduction, convection, and radiation.

Evaporation is the most powerful means of heat loss to the surrounding environment. High humidity limits evaporation heat loss, and high ambient

temperature limits conduction and convection heat loss. Dehydration limits heat transport to the body surface and also limits sweating.

A SHARED RESPONSIBILITY

Heat-related running injury and heat stroke caused by the exertion of running can be prevented with proper planning by the race organizing committee and proper preparation and good judgment by you. Preventing all exertional heat stroke (EHS) is probably not possible because we cannot control the individual risk variables during running. Primary prevention of EHS is the responsibility of the race administration, but each of us also has the responsibility of knowing how well we cope with hot running conditions.

The race administration is also responsible in high-risk conditions for the secondary prevention of excess morbidity and mortality associated with exertional heat stroke in the circumstances where it is likely to occur. Ironically, it has been shown that participants in shorter, faster road races are at greater risk for EHS than participants in longer, slower races like the marathon, although EHS can—and sometimes does—occur in marathon and longer distance races. The rapid generation of excess metabolic heat in a runner combined with delayed or impaired heat removal puts the faster-paced runners at greater risk.

EHS AND EXERTIONAL HYPERTHERMIA

Definitions of exertional heat stroke and exertional hyperthermia are not chiseled in stone and include a “floating” temperature based on the presence of heat stroke symptoms. These symptoms are normally associated with abnormal brain function. In general, a rectal temperature greater than 104 degrees F is considered exertional hyperthermia.

The clinical picture of EHS is best described as elevated body temperature and altered central nervous system function. EHS victims will most often be sweating and will not always feel hot to the touch. The only adequate assessment of body temperature in the suspected EHS casualty is to take a rectal temperature. The aural canal or tympanic membrane temperature analog thermometers measure a shell temperature in sweating athletes and can easily miss the heat stroke victim.

The symptoms and signs to watch out for with EHS include these: ashen skin color, vacant stare, dizziness, fatigue, weakness, impaired judgment, hyperventilation, flushing, chills, and intense thirst. None of these symptoms or signs is specific for heat stroke, but they should raise the suspicion that heat stroke may be present.

The most ominous sign of heat stroke is the presence of abnormal brain function involving bizarre behavior, memory loss (especially event details and name), loss of hind limb function, inability to walk alone, collapse, delirium, stupor, or coma. The presence of the symptoms and signs should alert runners and medical staff of a potential medical emergency. Immediate evaluation and cooling measures should be started.

If the rectal temperature is greater than 104 degrees F and central nervous system changes or other heat stroke symptoms are present, EHS is probably the cause. Immediate cooling treatment can be life-saving in this situation, and delays in applying a radical cooling treatment can result in increasingly severe complications.

There is probably a continuum of changes and symptoms that occur in a runner during the transition from overheated (external hyperthermia) to a full collapse from heat stroke. Exertional heat stroke can ultimately lead to a serious medical injury or death, so preventing EHS and knowing the signs of heat stroke are critical to your safety as a runner.

KNOW THE RISKS

Take it upon yourself to know the risk of variables for EHS and understand the environmental parameters that increase the risk of heat stroke. Be prepared to modify your physical activity to decrease your individual risk of EHS.

High humidity associated with high temperature poses the greatest risk to the body’s ability to dissipate heat and cope with elevated body temperature, especially if it is associated with intense activity or fast-paced races. The risk of heat injury begins to rise rapidly above 65 degrees F and 50 percent relative humidity. With intense work, you can generate 1,000 Kcal of heat per hour of activity, which can raise the body temperature of an averaged-sized runner into the hyperthermic range in 20 to 30 minutes. A fast-paced road race run in hot and humid conditions puts you at risk for hyperthermic injury in 30 to 45 minutes. In longer races, like the marathon, the prolonged, continuous activity can result in hyperthermia despite the slower pace.

Itis important to underscore the role of fluid in countering this process. How much fluid you take in while you run or race affects your body’s ability to transport heat through the circulatory system and to lose heat through sweating. There are numerous scientific studies graphically illustrating the effect of dehydration on heat storage and performance. A dehydrated runner will have a higher core temperature, an increased heart rate, a lower cardiac output, and an increased perceived exertion at the same workload compared to a well-hydrated runner.

Drinking fluids during races will not only improve your performance, it will also protect the cooling system during activity. Taking in fluids during your training is essential to being able to tolerate taking in fluids during a race. You have to “practice” this fluid replacement strategy on a regular basis on training runs.

GETTING COMFORTABLE WITH HEAT

Acclimatizing, or physiologic adapting, is critical to performing successfully in the heat and takes at least 10 days of exposure before it kicks in. Gradual and progressive exposure to increasing heat loads during training is the safest way to acclimatize your body to hot conditions. You can induce acclimatization more rapidly with harder training, and athletes who have a higher cardiorespiratory fitness level at the beginning of heat training and runners with a greater VO,max can acclimate to heat faster.

The physiologic effects of acclimatization include decreased heart rate, increased plasma volume, earlier and increased sweating, decreased skin blood flow, and decreased Na+ (sodium) losses with activity in the heat. The end result of acclimatization is decreased core body temperature, increased exercise tolerance time, and decreased perceived exertion in the heat. The greatest improvement in acclimatization occurs after 8 to 12 weeks of exposure, and nearly daily exposure to heat is required to maintain this adaptation. You can

remain acclimatized with as little as 30 minutes in the heat per day. You can lose your adaptation to heat in a few days to a few weeks.

With the ease of modern travel, it is possible for you to enter “hot” races elsewhere in the world during a cold season in your home state. You can induce partial acclimatization before you leave by wearing extra clothing while training in the cooler conditions. (An unexpectedly hot day in the spring or fall can also catch you unprepared for the heat, and in such unseasonably hot conditions, knowing that exertional heat stroke has occurred in relatively cool conditions with temperatures less than 60 degrees F, your decision to race is a personal one.)

When Does the Risk of Heat Injury Increase?

Several other factors increase the risk of heat injury in road racing. Younger adolescents and children as well as older adults are at greater risk in the heat— the younger groups because of their larger mass-to-surface area ratios, the older age group because of decreased efficiency of the heart pump (the circulatory system transports heat around the body as well as oxygen). Health deficits and recent illness will also decrease your resistance to heat and exaggerate the decrease in performance associated with heat. Finally, some medications and drugs will affect your ability to withstand heat during exercise. Always check with your doctor regarding the risk of activity in the heat while on prescription drugs, especially diuretics and tricyclic antidepressants. Remember also that over-the-counter drugs containing sympathomimetic amines (e.g., psuedofed, most cold preparations, ephedrine, antihistamines combined with decongestants) can interfere with your body’s ability to dissipate heat. Creatine and other supplements may also reduce heat tolerance. As always, alcohol and other recreational drugs can increase the risk of heat stroke and hyperthermia, and they will do little to improve performance.

AT WHAT TEMPERATURES DOES THE BODY PERFORM BEST?

Athletic performance is best when your core body temperature stays in the normothermic body temperature range of 99 to 101 degrees F. Athletes who run in hot conditions almost all drop out of the activity once the rectal temperature is above the 101 to 104 degree F range.

When the winning times of various races are plotted against heat stress measures like ambient temperature, wet bulb temperature, and wet bulb globe temperature, there appears to be an optimum heat load above and below which

times are slower. For ambient temperature this is usually around 50 degrees F for the marathon.

Higher heat loads can also adversely affect other performance indicators like exercise time to exhaustion, perceived exertion, and personal motivation. At 50 degrees F, the time to exhaustion with continuous activity is 94 minutes, compared to 80 to 85 minutes at 40 degrees F and 70 degrees F. This finding is also seen at the finish line and in the medical care areas of distance running events where the incidence of race injury rises in the heat.

WHAT REALLY HAPPENS DURING ROAD RACES?

Data accumulated at several running events illustrate the increased risk that hot conditions create for the runners in competition. These data are especially powerful when you compare the same event under different conditions.

The 7.1-mile Falmouth Road Race on Cape Cod in Massachusetts is run on the third Sunday in August, approximately 60 days after the summer solstice. Each year, 7,000 to 8,000 entrants line up to begin the coastline race, which starts in mid-morning and is usually run under conditions of increased heat injury risk. The temperatures are often greater than 65 degrees F with relative humidities in the 50 to 90 percent range. It is not unusual for the race start temperature to be in the high 70s or low 80s.

Each year several participants finish the race with body temperatures greater than 106 degrees F, and 10 to 15 of these runners suffer EHS. The rate of EHS during the Falmouth Road Race is one or two per 1,000 entrants. The vast majority of the treated runners walk away from the finish area in good condition because the race medical team is able to identify and treat the runners with EHS immediately and effectively. Without the continued diligence of the medical team, the race could not be run in August.

In comparison, another race in Falmouth is run on the same course in November, and there are no problems with heat stroke in the cool fall conditions. The contrast on the same course in “hot” and “cool” conditions is striking from a medical perspective. It would be interesting to see the performance data for individual runners on the same course in the different conditions.

Now let’s examine the Twin Cities Marathon of Minneapolis-St. Paul, Minnesota. With approximately 100,000 entrants in 16 years, Twin Cities has had fewer than 25 runners with rectal temperatures greater than 106 degrees F, and only five finishers with EHS.

The race starts at sunrise and is scheduled for a cool time of the year in early October, approximately 100 days after summer solstice. Four of the five runners with EHS participated in the three races that had a start temperature greater

than 55 degrees F. The rates of heat stroke for the cool and warm conditions are 1.5 runners per 100,000 entrants and 8 per 100,000 entrants, respectively.

Even in the “hottest” conditions for Twin Cities, the races were in or very near the “green flag conditions,” with a wet bulb globe temperature of less than 65 degrees F. With most of the races run in cool conditions, the average allinjury rate is 18 per 1,000 entrants with a range of 13 per 1,000 entrants at 40 degrees F to 35 per 1,000 entrants at 65 degrees F. The “severe” medical injury rate is less than 2 per 1,000 entrants.

The Boston Marathon, run on the third Monday inApril, is scheduled roughly 100 days before the summer solstice. The National Weather Service records for average high temperature, average low temperature, and the average humidity on raceday are nearly identical to the average conditions for the Twin Cities Marathon in Minneapolis in the autumn.

The major difference, from the perspective of heat stress, is the noon start at Boston. The race has experienced a wide range of heat stress conditions, and the noon start requires the elite runners to race in the hottest part of the day while the slower runners finish in “cooling” conditions. Bruce Jones, MD, has shown that the incidence of “all injury” and the incidence of race dropouts increases with increasing wet bulb temperature. The average all-injury rate is 72 per 1,000 entrants with a range of 40 per 1,000 entrants at 45 degrees F wet bulb globe temperature to 125 per 1,000 entrants at 65 degrees F wet bulb globe temperature.

Of particular interest is the correlation coefficient for the data comparing injury and heat stress that shows that 70 percent of the risk of all injury in the Boston Marathon is correlated to the heat stress. Jones has also compared the Boston Marathon incidence of casualties on a warm (68 degrees F) versus a cool (48 degrees F) raceday. The incidence of symptoms associated with heat injury (including nausea, vomiting, and collapse) were all increased on the warm day. The occurrence of muscle cramping was equal in both warm and cool conditions, so we can assume that exercise-associated muscle cramping is probably not related to heat but rather to muscle and neural fatigue. Also of interest is the increased incidence of both ankle sprains and blisters in the warm conditions, possibly due to muscle fatigue and sweaty, wet feet.

Grandma’s Marathon in Duluth, Minnesota, is scheduled for the third Saturday of June, which is very near the summer solstice. Even with its current starting time of 7:30 a.m., the race has experienced a wide range of heat stress conditions. The odds ratio for “medical care” is 1.84 per 1,000 entrants if the average temperature is greater than 60 degrees F, and the odds ratio that runners will need to receive I.V. fluid in the finish area medical tent is 2 if the wet bulb temperature is greater than 55 degrees F, again pointing out the increased risk to the runner in warmer conditions.

PREVENTION STRATEGIES FOR EHS

As mentioned earlier, the primary prevention of EHS is a responsibility each runner shares with the race administration. Passive strategies—that is, ones that don’t require race participants to modify behavior—are the most powerful means of preventing heat injury and are within the complete control of the race administration.

Race scheduling, for example, determines the “inherent” risk of the race. A race scheduled away from the summer solstice will avoid peak radiant sun exposure and the highest ambient temperatures. Be an informed runner and find out what are the average high and low temperatures along with the average relative humidity and the extreme high temperature for raceday of the event you’re considering. You can learn this information via the National Weather Service in the reference section of any library. If the National Weather Service data indicate that a particular day in a particular location is beyond your personal heat limits, it may be prudent to avoid the race. Common sense dictates so.

The next factor in preventing heat injury is the race start and finish time. From the perspective of heat injury, the “safest” races will have early morning start times to avoid the heat of the day. This allows the elite runners to compete in the cooler and faster conditions and the slower runners to finish in warming rather than cooling temperatures.

If arace does not have a plan for extreme heat conditions, develop your own individual cancellation policy. The unfortunate reality of road racing is that runners often surrender their normal behavior controls to the race administration, assuming the race will only be run if the conditions are in a safe range for all competitors.

The American College of Sports Medicine (ACSM) has road race recommendations for hazardous heat conditions, designed to guide race administrators in their effort to prevent heat injury. The ACSM heat stress prevention cascade is based on wet bulb globe temperature, which accounts for humidity, radiant heat, and ambient temperature.

Some simple heat stress guidelines are as follows:

* temperature of 65 degrees F and relative humidity of 100 percent increases the risk of heat injury

* temperature of 73 degrees F and relative humidity of 100 percent dramatically increases the risk of heat injury

* temperature of 82 degrees F and relative humidity of 100 percent is dangerous for vigorous and continuous activity.

The responsibility to “cancel” an event is shared by runners and the event. If an event does not intend to cancel under any circumstances, then the race administration should at least publicize the environmental conditions and risks to the runners before the start of the race so each athlete can make a wise decision regarding the environmental risk of the day.

Several factors can influence the outcome of a race in hot conditions. The heat wave of 1995 in the Midwestern U.S. was studied by the Center for Disease Control (CDC), which found that as little as one half hour per day spent in an air-conditioned environment could make a difference between life and death for the elderly. A prerace air-conditioned environment may help runners withstand the heat stress of a race.

Acclimatization to heat with a gradual increase in heat exposure to race conditions will help you resist heat stress during competition. It takes one to two weeks to improve heat resistance. Be leery of a second and third day in “unexpected” heat. Hydration is critical to heat response, and you need free access to fluids during training and before, during, and after races.

Races scheduled in moderate to high-risk heat conditions should anticipate heat injury and develop triage and treatment protocols for the race. The race medical team should train the volunteers to recognize and treat exertional heat stroke on-site to decrease the risk of death by heat stroke. Low-risk race volunteers should be trained in recognizing and treating EHS.

SUMMARY

Race organizers should strive to develop competition opportunities away from the hot times of the year and move the start times to the early morning hours to improve performance and reduce the risk of heat injury. You need to be aware of race cancellation and modification policies (including a “no cancellation” policy), so you can make a rational decision regarding at the start of each race. Your risk of heat illness increases if you have been ill, are not well hydrated, well nourished, and well rested, and if the conditions are warmer than you can normally tolerate. Runner safety should take priority over tradition, sponsors, coaches, and fans in all events and individual decisions to participate in road races. Understanding heat illness and knowing your personal heat limits will make for safer racing and could save your life. Can you answer the

question, “When is it too hot for me to run safely?” 1

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