Wednesday, April 8, 2009


By: Larry Green, PhD, and Russ Pate, PhD

(CT's COMMENT: A good read for coaches interested in youth development. The only thing I disagree with is the contention that high volume run training can damage epiphyseal plates in growing athletes - the research overwhelmingly demonstrates that high impact traumas (ie. getting tackled, a hard fall, etc) can damage the plates, but relatively low impact repetitive strain (ie. running) does not. I certainly don't advocate high volume running for young athletes, I'm just pointing out that the rationale against high volume presented below is not supported by research. The rest is quite good. Note the complete absence of any reference to "optimal windows of trainability" and the "10,000 hour rule". It would seem that Dr. Green and Dr. Pate have done their homework.)

Peak Development
Chapter 1

The greatest single challenge in training young distance runners is accounting for the physical and psychological changes that occur during adolescence. These developmental changes greatly influence nutritional needs as well as physiological, psychological, and biomechanical capacities, so you need to know a little about growth and maturation to determine the best training for adolescents. In this chapter we discuss 10 developmental principles that guide training and racing for young distance runners.

Developmental Principle 1: Limit Training Before Puberty
We're often asked what the best age is for kids to begin training for cross country, road racing, and the distance events in track and field. That's a tough question because there is limited scientific research on the subject and anecdotes simply aren't reliable. Even so, the question is too important to overlook, because researchers and doctors have raised many concerns about the effects of competitive running on young runners. We developed our answer to the question of when training should begin by considering these questions: At what age are young people physically capable of running long distances? Do they adapt physiologically to training? What are the long-term psychological effects of training and racing at a young age? Are any health risks associated with early participation in distance running?
You might be surprised to know that children as young as six years are physiologically well suited for aerobic activities such as distance running. We know this from research on children's V02max, which is a measure of how much oxygen the muscles are able to use to fuel their contractions during maximal exercise. Individuals with high V02max values have superior aerobic fitness, which means that their heart and vasculature can supply their muscles with a sufficient amount of oxygen-rich blood and their muscles can quickly process the oxygen to generate energy. V02max is vital to success in distance running because muscles fatigue quickly if their demand for oxygen is not fully met.
Research shows that, pound for pound, normally active 6- to 8-yearolds have V02max values as high as, or sometimes even higher than, recreational adult runners who train 30 to 40 miles a week. Based on these findings, some exercise physiologists contend that children are natural endurance athletes. This view is backed by age-group records for distance races, such as U.S. marathon records for young runners. The records for 8-year-olds are 3:37:26 for boys and 3:13:24 for girls; for 11-year-olds the record is 2:47:17 for boys and 3:03:55 for girls. Many adult marathoners have trained extensively for years without reaching these marks.
Research also shows that young children adapt physiologically to endurance training in several ways that, at least theoretically, will improve their running performance. Before puberty, for example, children who perform moderate levels of endurance training will experience about a 10 percent increase in V02max, slightly less than the 15 percent increase observed, on average, in adults. You might conclude from this information that young children are capable of training for and competing in long distance races, but before you start planning programs for 8-year-olds, consider a few important points:
▪ Neither scientific nor anecdotal evidence suggests that distance runners must start training at a young age to reach their greatest potential. Most world-class runners did not begin training until they were in their mid- to late-teens. And, with very few exceptions, the children who have held age-group records for the 5K through the marathon have not developed into elite adult runners.
▪ Research consistently shows that, before puberty, physiological adaptations to training aren't always correlated with performance in long-distance events. For prepubescent children, the factors that best predict distance-running performance are simply related to physical maturity: Taller, stronger, and faster children lead the pack in distance races, just as they excel in other sports like basketball, baseball, and soccer.
▪ While many children have naturally high levels of aerobic fitness, making them physiologically capable of performing low-intensity endurance activities, they are very limited in generating energy for high-intensity activities such as an 800-meter race. The body has two primary systems for producing energy during exercise: the aerobic system, which operates when a sufficient amount of oxygen is available to the muscles, and the anaerobic system, which operates when the oxygen supply cannot keep up with the muscles' demand during high-intensity activity. One of the most consistent findings in pediatric exercise science is that the anaerobic system is not fully developed in children because it relies on enzymes and hormones that are released and accumulate during puberty.
▪ Physically immature youth who undertake systematic training are at high risk for injuries, abnormal growth and maturation, and psychological burnout. These points convince us that youths who haven't yet reached puberty should not train systematically for distance running. One reason for limiting training before puberty is that normal pubertal development can improve running performance on its own (see table 1.1). For example, the growth spurt of the lungs and heart, which occurs at an average age of 11.5 years in girls and 13.5 years in boys, boosts the delivery of oxygen rich blood to the muscles, which naturally increases VO2max. Another example is the elevated levels of growth hormone, which enable stronger muscle contractions, increasing running speed and efficiency.

Not all developmental changes automatically improve running performance, a point that also supports curbing early training. Take rapid growth in height-at the average age of 10.5 for girls and 12.5 for boys, the growth rate increases dramatically from approximately 5.5 centimeters (2.1 inches) per year to approximately 10.5 to 12 centimeters (4.1 to 4.7 inches) per year. The highest rate of growth, which is called peak height velocity, occurs at around age 11.5 for girls and 13.5 for boys. Now consider the 13-year-old boy who grows 4 inches over a single summer suddenly he's all legs. The growth spurt should improve his running by increasing leg length and thus stride length. However, he now has trouble coordinating his longer legs because the nervous system, which controls movement, doesn't immediately adapt to changes in limb length. Also, during the growth spurt different body parts grow at different rates. The feet and legs, for example, usually lengthen faster than the trunk, making many teenagers seem gangly or awkward. These developmental changes cause the rapidly growing runner to temporarily perform worse because his uncoordinated stride wastes energy, causing early fatigue.
Rapid limb growth also means that children who train intensely for distance running are at high risk for muscular and skeletal injury. Bones lengthen at each end in soft tissue called epiphyseal growth plates, which are very weak before and during the pubertal growth spurt. If the growth plates are stressed by heavy loads of running, fractures can occur. The growing athlete's joints and muscles are also susceptible to injury because muscle mass and strength develop more slowly than bone. Eventually the epiphyseal growth plates will ossify, or harden, and muscle mass will increase, but until these two critical growth processes are complete, youth risk serious injury from excessive training.
Training before puberty can also affect sex-specific hormones, disrupting physiological development. Estrogen, for example, is a hormone that ensures normal growth and development in girls. Under certain conditions, including insufficient energy replacement through diet, some female runners do not experience the cyclic increases in estrogen that should begin during puberty. Girls who train excessively and do not consume a sufficient number of calories can not only experience delayed menarche, they can also experience amenorrhea, or cessation of menstruation. Although researchers have not discovered all of the long-term health effects of these conditions, they have linked them with extremely low bone density, because estrogen promotes bone development, much of which occurs during puberty. In the short term, low bone density can lead to stress fractures. In the long term, it can lead to osteoporosis, a severely disabling bone disease.
Fortunately, most young runners will avoid harmful levels of training. They'll stop pushing themselves long before reaching their limits. However, we've known at least a few young runners who were self-motivated to push to extremes, and we've known coaches and parents who pushed young runners too far. For these children, running injuries are common. Psychological burnout is an even more likely outcome. Take the 10-year-old who's running 40 miles a week and racing 10Ks on a regular basis. Eventually he'll grow tired of running, especially because improvement depends on increasing training loads over time. If a child is running 40 miles a week at age 10, at age 16 he'll need to run 70, or maybe even 90 or 100 miles, in order to keep improving. That much running leaves little time for activities other than school, sleep, and eating. When training becomes that consuming, it isn't fun any more, and most youths will drop out of running.
By the age of 12 for girls and 14 for boys, most youth will have experienced key developmental changes that enable them to safely begin a low mileage, low-intensity training program, leaving lots of room for gradual improvement over time. This doesn't mean that younger children shouldn't participate in distance running; they just shouldn't train systematically. Beginning at age 8 or 9, children who enjoy running may participate in fun runs and organized track and field programs that last a few months each year. Future distance runners will benefit from participating not only in middle-distance races (up to a mile), but also in sprinting, jumping, and throwing events. When track season is over, they should participate in soccer, basketball, and other youth sports, because it's important to develop all-around physical fitness before beginning specialized training for track and cross country (see developmental principle 3).

Effects of Puberty on Performance in Boys and Girls
Boys and girls experience several common developmental changes that lead to improved running performance, including increases in limb length and height, muscle mass, and dimensions of the heart and lungs. However, due to the effects of sex-specific hormones that are released during puberty-estrogen in girls and testosterone in boys-some changes tend to favor boys. For example, testosterone stimulates greater production of hemoglobin, an iron-containing protein in red blood cells. Hemoglobin is the vehicle for transporting oxygen in the blood, so blood with a higher concentration of hemoglobin can carry more oxygen to the working muscles. As a result of increased testosterone levels during puberty, then, boys experience an automatic improvement in VO2max, while in girls hemoglobin levels remain the same or decline.
Testosterone also stimulates muscle growth and the ability to produce anaerobic energy. At puberty, girls do get a little boost because their bodies produce a small amount of testosterone, but boys are at a much greater advantage because they produce far more testosterone than girls.
As a result of increased estrogen levels during puberty, girls tend to experience greater deposits of body fat. The average body-fat composition of 6-year-old girls is 14 percent, which increases to 25 percent in 17-year-olds.ln contrast, body-fat composition averages only 11 percent in 6-year-old boys and 15 percent in 17 -year-old boys. Runners who have relatively high percentages of body fat are at a disadvantage because fat is dead weight-it increases the energy required for distance running.
Estrogen also stimulates widening of the pelvic bones in young women. A wider pelvis can lead to misalignment of the legs, which worsens running technique and increases the risk of hip, knee, and ankle injuries.
These differences in the effects of puberty on boys and girls certainly don't mean that girl runners are doomed to poor performance and injuries. In most high school events, if the best girl runners competed in boy's races, they would place fairly high. Also, research clearly shows that girls who train for endurance sports have a significantly lower body-fat percentage than their nonathletic peers. Girls who train effectively experience marked increases in VO2max, which compensate for the slight decreases in hemoglobin that they experience. The same goes for the increased risk of injury girls face as a result of wider hips: Smart training prevents injuries.
Even so, the differences between the sexes are important because they call for individualized training. Because puberty has a small influence on muscle mass and strength in girls, they will benefit from a relatively high load of strength endurance training, including weight training, circuit training, and hill running. Training for flexibility and technique should be emphasized for girls who develop misalignment of the legs. And while sound nutrition is the key to success for all runners, it can playa more important role in performance for girls than for boys (see more about nutrition in chapter 3).

Developmental Principle 2: Consider Individual Differences
Table 1.1 shows the average ages at which key developmental changes occur. Striking individual differences characterize these hallmarks of puberty. For example, two 12-year-old boys on the same cross country team might begin puberty 5 or 6 years apart. The early-maturing boy might show the first signs of puberty at age 10, while his late maturing teammate might not get there until 15 or 16. The boys are the same chronological age, but they are very different in terms of biological age, or physical maturity. To develop effective programs, coaches must have a good sense of each individual's biological age and physical readiness for training. A herd approach, where everyone on the team does the same workout, can be harmful, especially when late-maturing youth try to keep up with early-maturing teammates who have gained advantages in size, muscle development, and physiological fitness. An awareness of individual differences in development is also critical for those who coach both girls and boys, because some pubertal changes influence running performance differently in girls and boys.
Determining precise biological age requires specialized medical equipment and expertise. However, coaches can still gain a good sense of their athletes' biological ages by being aware of the hallmarks of puberty. The obvious changes in secondary sex characteristics, such as breast development in girls and the appearance official hair in boys, indicate that puberty is underway. Also, as we discussed earlier, the pubertal growth spurt is a particularly important stage of development. Coaches should regularly measure their athletes' height to avoid overtraining during periods of rapid growth.
Besides accounting for individual differences in biological age, coaches must consider training age, which refers to the number of years that an athlete has been training regularly. A 16-year-old who has been training since 13 has a training age of 3 years, whereas a 16-year-old who just came out for the team 6 months ago has a training age of .5 years. Even though these two runners are the same biological age, they should train differently. The newcomer's program should include fewer miles and a greater emphasis on general training.

Developmental Principle 3: Emphasize General Fitness for Beginners
People tend to think of running as a natural movement that requires little athletic skill, unlike hitting a home run or sinking a three-pointer. From this perspective, runners just need a lot of endurance and willpower to succeed, so their primary training method should be piling on the miles. The more you learn about the science of distance running, however, the more you appreciate that performance is determined by various physical and psychological capacities that reflect athletic skills, including neuromuscular control, specialized forms of speed and strength, proper technique, and of course, endurance.
Consider the ability to control the elastic, spring-like properties of muscles and tendons, one athletic skill that underlies peak performance in distance running. The calf, thigh, and buttock muscles and their tendons stretch when the foot contacts the ground during the running stride. The stretched leg muscles generate force by contracting, or shortening, to propel the body upward and forward in the takeoff phase of the running stride. This active muscle contraction requires energy that is created through metabolic processes, or the breakdown of stored dietary nutrients, primarily carbohydrates and fats. In training and competition, distance runners can easily deplete a critical source of nutrient energy called glycogen, resulting in fatigue. Skilled runners, however, can generate propulsive force without completely relying on metabolic energy, sparing glycogen and thus delaying fatigue. Like stretching a rubber band, lengthening the calf, thigh, and gluteal muscles and their connected tendons creates elastic energy that can be used for powerful recoil, which helps propel the runner's body upward and forward. Runners who can take advantage of the elastic energy in their muscles and tendons get something like a free ride-their legs behave like a bouncing ball or a pogo stick, generating force without using up precious metabolic energy sources.
The ability to use elastic energy isn't automatic. It requires great muscle strength and neuromuscular control, or the ability to precisely time muscle contractions. Just before the foot contacts the ground, a skilled runner generates neural commands to contract the muscles that will be stretched on impact. These contractions stiffen the springs, so to speak, of the muscles and tendons for more powerful recoil. Runners can't develop this skill by piling on the training miles. In fact, research shows that long, slow distance running dampens the springiness of muscles and tendons, impairing their ability to generate elastic energy. Runners can develop this skill instead through methods such as circuit training and technique drills. Also, games such as basketball and ultimate Frisbee train the neuromuscular system to take advantage of elastic energy. (You'll learn how to incorporate these methods into training programs in part II.)
Figure 1.1 illustrates the fitness capacities that are essential for success in distance running. In the lower part of the figure are general fitness capacities, which can be developed through training that doesn't directly simulate the physical and mental demands of a distance race. Consider cardiovascular fitness, the capacity of the heart and the vascular system (arteries, capillaries, and veins) to supply the muscles with sufficient oxygen-rich blood and rapidly remove metabolic waste products like lactic acid. To develop this general capacity, runners don't always need to run; instead, they can try swimming, bike riding, or even in-line skating. Or, to develop strength endurance, the capacity to generate forceful muscle contractions over a long time under conditions that demand a high power output, such as running uphill or in sand, runners can lift weights or do circuit training.

In the middle part of figure 1.1 are race-specific fitness capacities, which can be developed through training that simulates the demands of competition. To develop race-specific fitness, runners must train by covering competitive distances at racing speeds, using high-intensity interval training, or participating in time trials or actual competitions.
The top part of figure 1.1 represents mental fitness, which is essential for success in distance running. Mental fitness is so important that an entire developmental principle, 6, is devoted to it.
Programs for young runners should emphasize general capacities because they form a fitness base that helps the athlete undertake specialized, high-intensity training. Consider an 800-meter runner's interval training session for developing race-specific fitness: 4 X 200 meters at 800-meter race pace, with a 20-second recovery period between each 200. To perform this high-intensity session successfully and safely, the runner must have strong general fitness, including ample flexibility and sound technique to move her limbs through the extensive range of motion required for such fast running. If her hamstring muscles are tight and her range of motion at the hip joint is limited, she risks straining or tearing those muscles. If her technique is wanting-let's say she's overstriding, which creates a braking action with every foot strike-she'll waste energy and fatigue quickly. Clearly, without basic strength endurance and neuromuscular control, her running technique suffers. In addition, if she hasn't developed cardiovascular endurance, she won't recover adequately during the 20-second interval between the 200s.
When we focus on how to design training in part II, you'll see that methods for developing general fitness capacities are especially important for beginners and for all runners in the initial stages of preparing for upcoming competitive seasons. However, this emphasis doesn't mean that a beginner's program should not include race-specific methods like high-intensity interval training. We recommend mixing all the types of training throughout a season, starting out with a relatively low percentage of specialized training and increasing it gradually.

Developmental Principle 4: Increase Training Loads Gradually
Designing successful training programs is a matter of determining appropriate workloads, which are defined by volume, intensity, and frequency. Volume means the amount of training, which includes the number of miles or kilometers covered. Intensity refers to the effort exerted, which is reflected in the speed of a run. Frequency is defined by how often the athlete trains. There are two reasons for starting with manageable training loads and increasing them gradually. First, athletes who do too much too soon limit their potential for building up to advanced training loads, and second, the three components must systematically increase in order for the athlete to improve.
Marsha is a 15-year-old whose training age is 1.5 years. Marsha currently averages 18 miles over four days of training per week, including the moderate-intensity running she does to develop cardiovascular endurance as well as the high-intensity running that she does to develop anaerobic fitness and race-specific fitness. To ensure progressive improvement, Marsha's coach will increase her weekly volume over time: 26 miles (age 16), 34 miles (age 17), and 42 miles (age 18). As the total volume increases, so should the intensity and frequency. At age 15, Marsha might do one fast interval session per week to develop anaerobic power and race-specific fitness. By 17 or 18, she might do two or three interval sessions per week. In addition, Marsha's overall frequency of training might increase from four to six or seven days per week between ages 15 and 18.
Because no simple formula exists for determining optimal increases in training loads, the best coaches weigh many factors, including the runner's developmental status, motivation, history of responding to certain types of training, and potential for handling training loads over a career. This sort of planning is guided by well-defined goals. The process of setting individualized goals and designing the optimal training loads for achieving them is called periodization. Part II will guide you through periodization step-by-step.

Developmental Principle 5: Increase Competition Distances Gradually
For developing racing fitness and skill, we advise starting with shorter races and increasing the distances from season to season and year to year. In track competition, for example, beginners should focus on the shortest distance race-800 meters. With training and experience, runners can move up in distance if they show promise at and enjoy the longer races. Why start out with short races? The young runner must learn that successful racing means running as fast as you can over a given distance without slowing down and losing form. It's very difficult for beginners to accomplish this objective in a long race like 5,000 meters because they simply lack the concentration and pacing skills to maintain a fast pace for that long.
Table 1.2 provides guidelines for increasing distance with chronological and training age. These guidelines are flexible. For example, a 12-year-old who has just begun competing doesn't always have to run 800 meters. He will benefit from participating on occasion in other races, from 400 to 3,000 meters. Whatever the distance, a key focus in competition should be to run the race at the fastest pace possible-a pace that is neither too easy nor too hard to maintain. By starting out with shorter races, beginners will learn this focus more quickly than if they try to trudge through longer events.

Developmental Principle 6: Emphasize Training for Mental Fitness
While the physiological demands of distance running are obvious, physiological fitness alone is insufficient. Physiological fitness must be matched by mental fitness, which is characterized by supreme willpower and motivation, self-confidence, the ability to regulate how "psyched up" one gets, skill in controlling effort and pace, and intelligence in formulating and executing racing tactics. While training for physiological fitness has its limits, training for mental fitness isn't as restricted by developmental factors. Remember that physiological adaptations to training, such as increases in VO2max, don't necessarily predict improved running performance, at least until young runners are physically mature. Also, recall that runners who do a lot of physical training during periods of rapid physical growth and maturation risk musculoskeletal injuries. Young runners have much to gain by developing mental fitness, as you'll soon see.
Young runners have a lot of room for improvement in mental fitness because of their age-they simply have not had the deep and varied experiences in training and competition that build mental fitness. For example, one of the most important mental fitness skills in running is pacing. From studies on optimal patterns of energy expenditure during endurance activities, and from observing the pacing tactics of elite adult distance runners, we know that evenly paced running is optimal, but pacing is a skill that many young runners lack. They often run too fast in the early stages of training sessions and races. Particularly in track races, elite adult runners are able to judge and adjust their effort and speed in order to precisely hit target splits, such as 400-meter splits, along the way to achieving their final time goals. How many 14-year-old runners do you know who can do that?
The ability to precisely control effort and pace over a long distance requires extraordinary mental fitness. Just think about what's involved in pacing. The runner must continuously concentrate on how fast her limbs are moving, how hard she's breathing, and how fatigued she feels. Then she must compare this sensory information with a mental representation, based on memory, of how the effort should feel for the pace to be on target. Split times really help in determining and adjusting pace, but doing math on splits when you're fatigued is no simple mental task. Young runners can develop these skills through race-specific training methods. We provide examples of these methods in chapter 4 and part II.

Developmental Principle 7: Emphasize Proper Technique
We've talked about how young people are well suited for distance running because they have naturally high levels of aerobic fitness, indicated by their high VO2max measures. However, this advantage can be easily offset by another physiological determinant of performance, running economy, which reflects movement efficiency. Children and adolescents are inefficient runners; numerous studies demonstrate that young runners use significantly more oxygen than adult runners, which wastes energy and causes early fatigue. Having a high VO2max is like having a huge bag of money that you're hauling off to spend at your favorite store. Poor running economy, or a high oxygen cost for running at submaximal speeds, is like having a hole in the bottom of that bag. If you waste your fortune, it obviously doesn't count for much in the long run.
A major cause of poor running economy in youths is flawed technique, including overstriding, turning motions of the upper body, and flailing arms. These biomechanical flaws waste energy either by slowing the runner's forward progression or by diverting muscle force to counterproductive movements. Many flaws in running form are related to developmental factors. Earlier in this chapter, for example, we discussed how the adolescent growth spurt can temporarily impair coordination, thereby worsening running technique. Rapid growth can also weaken postural muscles in the abdomen and back, which are essential for stabilizing the upper body and avoiding counterproductive movements. Sufficient technique training, especially for beginners, is necessary in order to break bad habits and to prevent runners from acquiring wasteful movement patterns that will be difficult to correct later on.
In addition to improving performance by conserving energy, technique training can prevent injuries. Flaws such as overstriding place excessive stress on bones, joints, and muscles. Sound technique smoothes out the distribution of forces loaded on the musculoskeletal system, reducing injury risk. In chapter 5, we discuss the details of how technique influences performance and injury risks, and we present tips for optimal running form. Chapter 6 covers specific technique drills and other methods, such as weight, circuit, and flexibility and mobility training, that are critical to developing efficient running form.

Developmental Principle 8: Set Your Sights on Self-Improvement
Perhaps, like us, you're in the habit of going for long runs on weekend mornings-along endless country roads, deserted city streets, or winding mountain trails-feeling like you're the sole person on earth. If so, you know that runners dream fantastic dreams. If you're a young runner, maybe you dream of qualifying for your state championship, earning a college scholarship, or even winning a medal in the Olympic Games. Dreams are powerful fuel for pushing through the long runs, the exhausting interval sessions, and the last stages of grueling races. The reality, of course, is that only a small percentage of today's young runners will develop into tomorrow's Olympic athletes, and those who do reach the world's elite ranks get considerable help from their genes. Even so, all young runners can be on par with elite runners on at least one account: focusing on self-improvement as the most important measure of success.
Next time you read an article about a world-class runner or see one being interviewed on television, pay attention to what she talks about. It won't be about the competitors, the championships, the medals, or the money. Instead she'll focus on ways to improve. "I need to work on my kick, because I know that I can run faster over the last 400," she'll say. "I'm losing form going uphill, so I need to include more hill training in my program," or, "I'm letting my nerves get to me too much before races, so I'm planning to experiment with relaxation techniques."
The bottom line is that self-improvement from day to day, season to season, and year to year paves the road to your highest goals and results in unparalleled satisfaction, making the hard work worthwhile and, yes, even enjoyable.

Developmental Principle 9: Never Compromise Health
Without question, training for young distance runners should be designed for peak performance, but given the physical demands of running, a fine line often separates peak performance from injury and illness. To keep their athletes on the right side of the line, coaches must adhere to the philosophy that training should never compromise health. In the long run, there is no more important objective of youth sport than influencing values and behaviors in ways that ensure a healthy lifestyle in adulthood. Participating in cross country and track is especially valuable considering the high incidence of diseases that are linked to physical inactivity, including obesity, high blood pressure, coronary heart disease, diabetes, and even some forms of cancer. If you're a parent or a coach, you can pave the young runner's path to a physically active life by emphasizing healthy training practices such as increasing training loads gradually, including methods such as technique and strength training that are geared toward injury prevention, stressing optimal nutrition, watching for signs of overtraining, and forcing athletes to rest if they are injured or ill.

Developmental Principle 10: Make It Fun
The adage "last but not least" applies doubly here. That's because none of the previous principles has much practical value if young runners don't view their experiences as fun. All of the knowledge in the world about the science of distance running doesn't amount to much unless the coach knows how to make training interesting and enjoyable. For young runners to have fun, the coach must possess personal skills such as a caring attitude, a creative imagination, and a knockout sense of humor. Part II includes suggestions for making training fun with games, contests, and special events.

Striding Ahead
Developing training programs for young distance runners is best informed by knowledge about human development, specifically adolescent growth and maturation. We've stressed this point in the 10 developmental principles, which form the foundation of our philosophy on training young runners. You'll see these principles in action in part II, guiding our specific recommendations for training. First, however, we'll help you learn more about the science of distance running and its physiological basis, which is necessary for understanding the reasons behind our recommendations.

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