Biomechanics For Dummies

Steve McCaw

• Publisher: For Dummies
• Year: 2014
• ISBN:
  9781118674765
• Edition: 1
• Topic: Ciencias biológicas
• Subtopic: Biología

A thorough explanation of the tenets of biomechanics

At once a basic and applied science, biomechanics focuses on the mechanical cause-effect relationships that determine the motions of living organisms. Biomechanics for Dummies examines the relationship between biological and mechanical worlds. It clarifies a vital topic for students of biomechanics who work in a variety of fields, including biological sciences, exercise and sports science, health sciences, ergonomics and human factors, and engineering and applied science. Following the path of a traditional introductory course, Biomechanics for Dummies covers the terminology and fundamentals of biomechanics, bone, joint, and muscle composition and function, motion analysis and control, kinematics and kinetics, fluid mechanics, stress and strain, applications of biomechanics, and black and white medical illustrations.

• Offers insights and expertise in biomechanics to provide an easy-to-follow, jargon-free guide to the subject
• Provides students who major in kinesiology, neuroscience, biomedical engineering, mechanical engineering, occupational therapy, physical therapy, physical education, nutritional science, and many other subjects with a basic knowledge of biomechanics

Students and self-motivated learners interested in biological, applied, exercise, sports, and health sciences should not be without this accessible guide to the fundamentals.

Part I

Getting Started with Biomechanics

For Dummies can help you get started with lots of subjects. Visit www.dummies.com to learn more and do more with For Dummies.

In this part…

• Identify the “bio” and the “mechanics” parts of biomechanics.
• Get a refresher on the basic math and geometry skills you need to solve biomechanics problems.
• Discover a systematic approach to resolving or composing vectors using SOH CAH TOA.
• Understand the fundamental terms and concepts of biomechanics.

Chapter 1

Jumping Into Biomechanics

In This Chapter

Defining biomechanics

Introducing linear and angular mechanics

Using biomechanics to analyze movement

Kinesiology is the science focused on the study of motion. It's the core area of many majors at colleges and universities for students interested in exercise or movement science, athletic training, and physical education teacher education. A degree in kinesiology can lead to a career in itself in teaching, exercise prescription, sports medicine, and coaching. In addition, many students study kinesiology at the undergraduate level because its focus on the human body provides a strong foundation for graduate study in physical therapy and medicine.

Biomechanics is one of the core courses in kinesiology. Along with the foundation knowledge from other core courses (including anatomy and physiology, psychology of sport and exercise, exercise physiology, and motor learning), biomechanics contributes to a basic understanding of human movement possibilities.

In this chapter, I introduce you to the subject of this book — think of this as the book in a nutshell — with plenty of cross-references so you know where to turn to find more information.

Analyzing Movement with Biomechanics

Biomechanics uses three branches of mechanics, along with the structure and function of the living body, to explain how and why bodies move as they do (see Figure 1-1). The different branches of mechanics are used to study movement in specific situations, and the systems of the living body determine what it's capable of doing and how it responds during movement.

Figure 1-1: The branches of biomechanics.

In this section, I give you a brief overview of the three branches of mechanics, along with the structure and function of the living body.

Mechanics

Mechanics is a long-established field of study in the area of physics. It focuses on the effect of forces acting on a body. A force is basically a push or a pull applied to a body that wants to make it move (see Chapter 4). Mechanics looks at how a body is affected by forces applied by muscle, gravity, and contact with other bodies.

I use the term body to refer to the focus of attention during an analysis. For someone walking, the body could be the person as a whole entity. But the body could also be an individual segment, like the walker's thigh, lower leg, or foot, or, going even further, an individual bone in a segment. For more on defining the body under analysis, turn to Chapter 4.

Rigid body mechanics

An applied force affects the motion of a body — meaning, it tries to make the body speed up or slow down. The motion can be large and involve a lot of body segments, like walking, or it can be small and involve only a couple of segments, like bending a finger. Both of these movements, and all other movements involving body segments, can be analyzed using rigid body mechanics.

Rigid body mechanics simplifies a body by modeling (representing) it as a single, rigid bar. A rigid bar can be used to represent the entire body (quite a simplification) or just the individual segments of the body. The modeled segments can be combined as rigid, non-deforming links joined at hinges (the joints) to represent any part of the body.

Consider your arm, made up of the complex anatomical structures of the upper arm, forearm, and hand. If you hold your arm out in front of you and bend and straighten your wrist and elbow, you'll notice that your skin shifts and folds and soft areas bulge as muscles change shape under the skin. Place a finger over the front of your upper arm, and feel the changing stiffness of the muscle when your arm bends and straightens. If you poke your skin with a finger, it sinks in a little bit. In rigid body mechanics, these changes in, or deformations of, the individual segments are ignored. The upper arm, forearm, and hand are considered to be separate, simple rigid links or sticks that move at the joints where they meet. The rigid link model of the human body is more fully explained in Chapter 8.

Fluid mechanics

Fluid mechanics is the branch of mechanics focused on the forces applied to a body moving in air or water. These fluids produce forces called lift and drag, which affect the motion of a body when a fluid moves over it, or as the body moves through a fluid.

Fluid mechanics is obviously applicable to swimming and water sports, but it's also useful when explaining how to make a soccer ball, tennis ball, or baseball curve through the air. For more on fluid mechanics, float on over to Chapter 11.

Deformable body mechanics

Deformable body mechanics focuses on the changes in the shape of the body that are ignored in rigid body mechanics. An applied force causes a deformation (change in shape) of the body by loading the particles of material making up the body. Deformable body mechanics involves looking at the loading and the motion of the material within the body itself.

The loading applied to a body is called a stress. The size and the direction of the stress cause deformations of the material within the body, called strain. The relationship between the applied stress and the resulting strain is useful to understand injury to and training of tissues within the body. Chapter 12 provides more detail on deformable body mechanics.

Bio

Bio is Greek for “life,” making biomechanics the science applying the principles of mechanics to a living body. Biomechanics is used to study and explain how and why living things move as they do, including the flight of a bumblebee, the swaying of a stalk of corn, and, more important for most of us, the movements of human beings.

Part IV of this book covers the “bio” of biomechanics, explaining aspects of the following systems important to the mechanics of movement:

• Skeletal system: The skeletal system, including bones, ligaments, and joints, provides the physical structure of the body and allows for movement. (See Chapter 13.)
• Neural system: The neural system, also known as the nervous system, including different types of nerve cells, ...