Objectives

This course is aimed towards upper level undergraduates and masters students

·         Apply principles of classical mechanics to the study of human motion

·         Describe motion with precise, well-defined mechanical and anatomical terminology

·         Describe the internal and external forces acting on the body during typical human activities understand how muscle actions control movements - Model muscle activation and movement

Introduction

Biomechanics has been defined as the study of the movement of living things using the science of mechanics (Hatze, 1974). Mechanics is a branch of physics that is concerned with the description of motion and how forces create motion. Forces acting on living things can create motion, be a healthy stimulus for growth and development, or overload tissues, causing injury. Biomechanics provides conceptual and mathematical tools that are necessary for understanding how living things move and how kinesiology professionals might improve movement or make movement safer. Most readers of this book will be majors in departments of Kinesiology, Human Performance, or HPERD (Health, Physical Education, Recreation, and Dance). Kinesiology comes from two Greek verbs that translated literally means “the study of movement.” Most American higher education programs in HPERD now use “kinesiology” in the title of their department because this term has come to be known as the academic area for the study of human movement (Corbin & Eckert, 1990). This change in terminology can be confusing because “kinesiology” is also the title of a foundational course on applied anatomy that was commonly required for a physical education degree in the first half of the twentieth century.

This older meaning of kinesiology persists even today, possibly CHAPTER 1 Introduction to Biomechanics of Human Movement 3 because biomechanics has only recently (since 1970s) become a recognized specialization of scientific study (Atwater, 1980; Wilkerson, 1997). This book will use the term kinesiology in the modern sense of the whole academic area of the study of human movement. Since kinesiology majors are pursuing careers focused on improving human movement, you and almost all kinesiology students are required to take at least one course on the biomechanics of human movement.

It is a good thing that you are studying biomechanics. Once your friends and family know you are a kinesiology major, you will invariably be asked questions like: should I get one of those new rackets, why does my elbow hurt, or how can I stop my drive from slicing? Does it sometimes seem as if your friends and family have regressed to that preschool age when every other word out of their mouth is “why”? What is truly important about this common experience is that it is a metaphor for the life of a human movement professional. Professions require formal study of theoretical and specialized knowledge that allows for the reliable solution to problems. This is the traditional meaning of the word “professional,” and it is different than its common use today. Today people refer to professional athletes or painters because people earn a living with these jobs, but I believe that kinesiology careers should strive to be more like true professions such as medicine or law.

Development

Biomechanics research on sports techniques sometimes tends to lag behind the changes that are naturally occurring in sports. Athletes and coaches experiment with new techniques all the time. Students of biomechanics may be surprised to find that there are often limited biomechanical 6 FUNDAMENTALS OF BIOMECHANICS The two major applications of biomechanics are to improve human movement and the treatment or prevention of injury.

Biomechanics principles must be integrated with other kinesiology sciences to solve human movement problems, like in the qualitative analysis a round off and back handspring. Studies on many techniques in many popular sports. The vast number of techniques, their variations, and their high rates of change and innovation tend to outdistance biomechanics research resources. Sport biomechanics research also lags behind the coaches and athletes because scientific research takes considerable time to conduct and report, and there is a lack of funding for this important research. There is less funding for biomechanical studies aimed at improving performance compared to studies focused on preventing and treating injuries.

Students looking for biomechanical research on improving sports technique often will have fewer sources than students researching the biomechanics of injury. While technique is always relevant in human movement, in some activities the psychological, anatomical, or physiological factors are more strongly related to success. Running is a good example of this kind of movement.

There is a considerable amount of research on the biomechanics of running so coaches can fine tune a runner's technique to match the profile of elite runners (Cavanagh, Andrew, Kram, Rogers, Sanderson, & Hennig, 1985; Buckalew, Barlow, Fischer, & Richards, 1985; Williams, Cavanagh, & Ziff, 1987). While these technique adjustments make small improvements in performance, most of running performance is related to physiological abilities and their training. Studies that provide technique changes in running based on biomechanical measurements have found minimal effects on running economy (Cavanagh, 1990; Lake & Cavanagh, 1996; Messier & Cirillo, 1989). This suggests that track coaches can use biomechanics to refine running technique, but they should only expect small changes in performance from these modifications.

 Human performance can also be enhanced by improvements in the design of equipment. Many of these improvements are related to new materials and engineering designs. When these changes are integrated with information about the human performer, we can say the improvements in equipment were based on biomechanics. Engineers interested in sports equipment often belong to the International Sports Engineering Association (http://www.sportsengineering.org/) and publish research in ISEA proceedings (Subic & Haake, 2000) or the Sports Engineering journal. Research on all kinds of equipment is conducted in biomechanics labs at most major sporting goods manufacturers.

Unfortunately, much of the results of these studies are closely guarded trade secrets, and it is difficult for the layperson to determine if marketing claims for “improvements” in equipment design are real biomechanical innovations or just creative marketing. There are many examples of how applying biomechanics in changing equipment designs has improved sports performance. When improved javelin designs in the early 1980s resulted in longer throws that endangered other athletes and spectators, redesigns in the weight distribution of the “new rules” javelin again shortened throws to safer distances (Hubbard & Alaways, 1987). Biomechanics researchers (Elliott, 1981; Ward & Groppel, 1980) were some of the first to call for smaller tennis rackets that more closely matched the muscular strength of young players (Figure 1.4). Chapter 8 will discuss how changes in sports equipment are used to change fluid forces and improve performance.