Sport mechanics offer a performance edge for athletes
Sport scientists work in the field of biomechanics, a discipline that assesses the effects of forces on humans and, vice versa, the effects of forces that humans apply. It’s obvious that gravity and air resistance, or even the forces that occur during collisions, make no distinction between nonsporting and sporting activities. A high jumper fights against gravity just as a person climbing stairs or a plane taking off does. Likewise, air resistance opposes both an automobile and an Olympic sprint cyclist. This tells us that the same mechanical principles used in our everyday world can be applied to sport. A typical example of biomechanics is shown in figure 1.1, with the forces generated overlaid on top of the human anatomy. The combination of this mechanical principle with human anatomy allows you to understand sport mechanics.
In sport, mechanical principles are nothing more than the basic rules of mechanics and physics that govern an athlete’s actions. For example, if a coach and an athlete understand the characteristics of the earth’s gravitational force, they know what must be done to best counteract the effect of this force and, conversely, what actions must be performed to make use of it. A springboard diver who is aware that gravity acts perpendicularly to the earth’s surface has a better understanding of what trajectory gives an optimal flight path for a dive. Similarly, wrestlers quickly learn that gravity is their friend when they’ve got their opponents off balance. On the other hand, if they don’t maintain their own stability, gravity can team up with their opponents! Ski jumpers understand that if they flex their legs and bend forward as they accelerate down the inrun, they reduce air resistance. This body position allows them to accelerate to an optimal speed in preparation for the takeoff. Once in flight, ski jumpers counteract the force of gravity by making use of air resistance. They extend their legs and lean forward to deflect air downward. In response, the air pushes them upward. It is this variation in the use of gravity and air resistance that helps Olympic ski jumpers fly to distances in excess of 130 m (426 ft).
There are many forces on earth besides gravity and air resistance. These forces act in different ways, and if you’re in a contact sport you must also consider the forces produced by your opponents. If you are a coach and you understand how all these forces interrelate, you’ll be better able to analyze an athlete’s technique and improve the athlete’s performance. If you are an athlete and you have this knowledge, you’ll understand why it’s better to apply muscular force at one instant than at another and why certain movements in your technique are best performed in a particular manner. Even as a spectator and sport fan, you’ll find that an understanding of basic mechanical principles helps you become more knowledgeable and appreciative of what it takes to produce an excellent performance.
In sport, the laws of mechanics don’t apply to the athlete alone. Mechanical principles are used to improve the efficiency of sport equipment and playing surfaces. Modern track shoes, speed skates, skis, slick bodysuits for swimming and cycling, and safety equipment (such as pole-vault landing pads) are all designed with an understanding of the external forces that exist on earth and the forces that an athlete produces. This knowledge has been instrumental in raising the standard of performance in every sport.
When we compare the performances of two athletes, we often say that one of the two athletes has better form, or more precisely, that one athlete has better technique than the other. By technique we mean the pattern and sequence of movements that athletes use to perform a sport skill, such as a forearm pass in volleyball, a hip throw in judo, or a somersaulting dive from the tower. Elite athletes create the image of having all the time in the world to complete a complex task, and in biomechanical terms they have effectively refined their kinetic link (that is, the timing of movement between successive limbs, like the thigh, shank, and foot during kicking).
Sport skills vary in number and type from one sport to the next. In some sports (e.g., discus and javelin), there is only one skill to perform. A discus thrower spins and throws the discus—nothing more. As such, this activity is defined as a closed skill; that is, it is closed to the thrower because the thrower is the person who determines when to start to spin and when to release the discus. But in tennis, players perform forehands, backhands, volleys, and serves; and all these actions depend on what the opponent has done and are defined as open skills. Each skill, whether it’s a tennis serve or a discus throw, has a specific objective determined by the rules of the sport. In a serve, a tennis player wants to hit the ball over the net and into the service area in such a way that the opponent cannot return it. A discus thrower aims to throw the discus as far as possible, making sure that it lands in the designated area. Both athletes try to use good technique so that the objectives of each skill are achieved with the highest degree of efficiency and success, and sport mechanics is required to understand this process.
An athlete can perform a skill with good or poor technique. Poor technique is ineffective and fails to produce the very best results. In the worst-case scenario, poor technique can also cause injury to the athlete as well as to the people surrounding the activity. You can see plenty of poor technique at any public driving range—and, along with poor technique, inferior results! Hooks and slices are mixed in with wild swings that miss the ball entirely. Even if you know little about golf, you’ll be amazed by the variation you see in the performances of a single stroke. Now compare these recreational golfers with elite professional players. Although elite players differ in height, strength, and weight, the basic technique they use in their strokes is very much the same. From backswing to follow-through, you’re likely to see a smooth application of force that appears graceful and fluid. This efficiency of motion tells you that elite golfers use good technique, with a refined kinetic link. They practice for hours to hone this technique so that their actions become highly effective and get the job done.
Apart from minor differences, all top-class athletes, no matter what their sport, use superior technique based on the best use of the mechanical principles that control human movement. But it’s important to remember that the refined, polished movements you see in the technique of an elite athlete seldom occur by chance. They usually result from hours of practice, and more importantly, smart practice—the right type of practice. Likewise, it’s virtually impossible nowadays for an athlete to reach world-class status without the assistance of coaches and sport scientists who know why it’s better to perform movements one way rather than another. Today’s top athletes get help from knowledgeable coaches who critically observe their performances and tell them what is efficient movement and what is not. The coaches’ knowledge and sport science assessment, coupled with the athletes’ talent and discipline, help produce safe, first-rate performances.
What must you know in order to teach good technique? As an example, let’s look at what’s necessary when you teach a novice to drive a golf ball. When you introduce this skill, it’s an asset if you can demonstrate good technique, although this ability is certainly not essential. What’s more important is that you are able to analyze and correct faults in the novice’s performance and that you use good teaching progressions to lead the novice to a more refined performance. To do this you need a basic understanding of the mechanics of the golf drive, which means that you must know why certain actions in a golf drive are best performed in one way and not another. It’s the same when you coach or instruct classes in volleyball. A volleyball coach needs to know the mechanical reasons why certain movements get a player up in the air for a spike and why other movements do not. In baseball, a pitching coach aims to teach the most efficient actions for the windup, delivery, and follow-through. Similarly, a batting coach works to make the batter a more effective hitter. The golf, baseball, and volleyball coaches are using their knowledge of mechanical principles when they eliminate poor movements and replace them with actions that are more efficient. One of the best ways to transfer this knowledge is to use a variety of processes to communicate with the athlete. This can be enhanced with a variety of new technologies to provide feedback to the athlete.
Many coaches and athletes still follow traditional methods during training. They reason that “this is how it was done in the past and it worked well, so this is how we should do it now.” They have no idea why some movements may be good and others bad, why some are safe and effective while others cause injury and erratic actions. Then there are those coaches who are happy using a trial-and-error method. Occasionally they get good results, but more often they don’t. Many coaches teach their athletes a technique based on a world champion’s technique without taking into account differences in physique, training, and maturity. Similarly, young athletes often copy every action of a world-class performer, including idiosyncrasies that are mechanically ineffectual. For example, Al Oerter, four-time Olympic discus champion from 1956 to 1968, frequently inverted the discus as he swung his arm back during his windup. This action was simply a personal trait that added nothing to the mechanical efficiency of Oerter’s throwing technique, yet many young athletes copied it, believing that it would add distance to their throws. Or, a more comical example of copying idiosyncrasies was seen in the number of kids who attempted slam dunks with their mouths open and tongues hanging out. Why? Because this was a common characteristic of Michael Jordan!
Being able to distinguish between safe, mechanically correct movements and those that serve no purpose is essential for skill development. Coaches and athletes who blindly mimic the methods and techniques of others progress only so far. Sport Mechanics for Coaches will help you eliminate this haphazard approach. By developing a basic understanding of mechanics, you’ll be able to analyze performances and teach movement patterns that produce efficient technique. This will lead to better performances.
Technology is part of everyday life, and some of this technology has a place within sport. For example, people use a global positioning system (GPS) in their car, or when hiking to monitor how far they have traveled or how long it will take to arrive at the destination. Similar technology can be used in sport to determine how far an athlete has run during a game or to quantify how straight someone paddled a kayak. This modern-day knowledge can provide new feedback to athletes and thus tell them something they didn’t already know. Or at times this technology is merely telling them something that the coach has repeatedly said but that somehow didn’t get through.
How many times has a golf coach told a golfer, “You are lifting your head just as the club is making contact with the ball”? The golfer doesn’t feel her head moving and for a number of reasons doesn’t or can’t make a correction to her technique. If the coach uses a video camera to record her swing and then plays the video back, the golfer can see the fault in the mechanics. More advanced technology can measure the amount of movement, like how far the head lifted, and with the use of force transducers and EMG (electromyography), can measure the timing of muscle sequences. This type of monitoring with technology can provide a new approach to coaching; therefore, in understanding sport mechanics, we need to understand and incorporate technology into the training sessions.
Most people involved in coaching are reluctant to study sport mechanics; from experience they know it has meant tackling dry, boring texts loaded with formulas, calculations, and scientific terminology. These texts are frequently written by academics who fail to explain the relationship of good technique to the principles of mechanics in a manner that is meaningful to coaches and sport enthusiasts. You’ll be happy to find that Sport Mechanics for Coaches is a different type of book. This book contains few formulas or calculations, and it uses familiar measurements in both imperial and metric units. Whether you coach, teach, analyze, perform as an athlete, or watch as a fan, Sport Mechanics for Coaches is a book that you can learn from immediately.
To get the most from Sport Mechanics for Coaches, all you need is a desire to know how and why things work in the world of sport. In other words, if you have curiosity and a desire to improve, you’ll get a lot of useful information from this text. Here’s how:
You will learn to observe, analyze,and correct errors in performance.
This is the most important benefit you’ll get from reading Sport Mechanics for Coaches. This text will help you develop a basic understanding of mechanics, and by using this knowledge you will be able to distinguish between efficient and inefficient movements in an athlete’s technique. The information in this text will help you pick out unproductive movements and follow up with precise instructions that help optimize performance. You won’t waste time with vague advice like “Throw harder” or “Try to be more dynamic.” Obscure tips like these only confuse and frustrate the athletes you’re trying to help. One of the most effective ways to observe, analyze, and correct errors is through the use of technology—so we’ve added a section on technology within each chapter to provide you with some extra resources. On the other hand, if you’re the athlete and your coach is not present, a basic knowledge of sport mechanics will help you understand why you should eliminate certain movements in your technique and instead emphasize other actions.
You’ll be better able to assess the effectiveness of innovations in sport equipment.
When Greg LeMond of the United States won the Tour de France by a few seconds over Laurent Fignon of France, he certainly illustrated the value of fitness and determination. But equally as important, LeMond and the technicians who assisted him knew the importance of reducing wind resistance to a minimum, particularly during the Tour’s final time trial. They realized that if LeMond could maintain a low, dart-like body position and have the air flow smoothly over and past his body, he would spend less energy pushing air aside and could spend more energy propelling himself at high speed. This knowledge of mechanics paid off! It’s no different in other sports. You need to know what is gained from design changes in such items as golf clubs, tennis rackets, skis, speed skates, mountain bikes, and swimsuits. This edition has also added sections titled “What Does _____ Mean in Sport?” to various chapters to provide several examples of real applications in sport. Sport Mechanics for Coaches cannot teach you all there is to know in the world of sport equipment design because changes and modifications will continue to occur at an ever-increasing pace. But this text will certainly give you a foundation of knowledge on which you can build.
You’ll be better prepared to assess training methods for potential safety problems.
Think of an athlete squatting with a barbell on his shoulders. Where should your athlete position the bar? Should it be placed high on the shoulders or lower down? And what about the angle of the athlete’s back during the squatting action? What are the mechanical implications of a full squat compared to half and three-quarter squats, and how fast should the athlete lower into the squat position? If you know about levers and torque, you’ll understand why it’s dangerous to bend forward when you squat. Likewise, if you are familiar with the characteristics of momentum and understand how every action has an equal and opposite reaction, you’ll know that dropping quickly into a full squat puts tremendous stress on the lower back, knees, and hips. It’s possible that you have been teaching good technique but don’t fully understand why one way of performing the technique is potentially dangerous and another is not. Sport Mechanics for Coaches will give you the reasons. In gymnastics you will frequently see spotting techniques that provide a high level of safety, and you’ll also see other techniques that endanger both the gymnast and the spotter.
To further explain these concepts we’ve also added a new section, “How to Measure,” within each chapter. This new section describes several ways to measure what is happening in sport that can then be used to assess training methods. By reading Sport Mechanics for Coaches you’ll discover why efficient spotting requires an understanding of balance, levers, torque, and the momentum generated by the gymnast performing the skill. This information will help you teach safe spotting techniques in gymnastics and good technique in weight training. Of course, Sport Mechanics for Coaches is not limited to these two sports. You can apply the mechanical principles that you read about to every sport.
You’ll be better able to assess the value of innovations in the ways sport skills are performed.
In sport, our capacity for reasoning and creativity has been responsible for the advances in talent selection, technique, training, and equipment design. We all possess a tremendous capacity for creativity, and to be a good coach you must use this creativity to search for better ways to improve your athletes’ performance. All athletes differ in physique, temperament, and physical ability; what works for one athlete will not necessarily work for another. Similarly, a young athlete will differ dramatically from a mature athlete. To help your athletes achieve top-flight performances, it’s good to learn why sport techniques are performed as they are and to be prepared to modify certain aspects of these techniques in order to fit the athletes’ age, maturity, and experience. There are many examples of the willingness of coaches and athletes to try out new ideas. In team games, think of how coaches modify attack and defense formations relative to the team they will face in an upcoming contest. Among athletes, think of how the creativity and experimentation of Dick Fosbury revolutionized the high jump and how the glide and rotary techniques have increased the distances thrown in the shot put. In gymnastics, consider the number of skills named after their creative inventors (such as the “Thomas Flair,” named after former U.S. gymnast Kurt Thomas). So be curious and learn the how and why of technique. At the same time, be creative and willing to experiment, and be sure to encourage your athletes to use their own creative capacities as well. Always look for ways to improve your understanding of the sport you are coaching. Be a coach, an analyst, and an innovator all at the same time!
You will know what to expect from different body types and different levels of maturity.
If you understand the mechanical principles governing the techniques of your sport, you’ll understand why young athletes, who are growing quickly have a tougher time maneuvering, changing direction, and coordinating their movements than more mature athletes do. You’ll realize that you cannot and should not expect young athletes to follow the same training regimens that you would demand of a more mature athlete. You’ll also understand why tall athletes with long arms and legs have an edge in some sports but are at a disadvantage in others. Similarly, you will realize why smaller athletes tend to have a good strength-to-weight ratio and can cut, turn, and shift more quickly than athletes who are taller and heavier.