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One of the most important athletic abilities in many sports is speed. Coaches often quip that luck follows speed because a fast athlete can arrive in a crucial situation before their opponent. Coaches that often have a good understanding of speed are in cross-country and track.The careful timing of various intervals of a race, commonly referred to as pace, can be easily converted average speeds over that interval. Pace (time to run a specific distance) can be a good kinematic variable to know,...

Injury Prevention

This chapter opened with the scenario of one of the most common injuries in sports, a non-contact sprain of the ACL. The large numbers of injuries to young female athletes has resulted in considerable research on how these injuries occur in landing, jumping, and cutting. Many biomechanical factors have been hypothesized to be related to increased risk of ACL injuries in sport peak vertical ground reaction force, knee flexion angle at landing, hamstring strength, and balance. A large prospective...

Qualitative Analysis Of Catching

As a volunteer youth football coach you are working with your receivers on catching passes. Many young players pick up bad habits from playing neighborhood pick-up football games or watching the pros get by with talent rather than optimal technique. The technique points and cues you typically use are listed in Table 10.5. Notice how the critical features are more advanced and specialized than the catching technique points in chapter 9 (e.g., Table 9.4). Which biomechanical principles are...

Forcetime Principle

The applied manifestation of Newton's Second Law of Motion as the Impulse-Momentum Relationship is the Force-Time Principle. If a person can apply force over a longer period of time (large impulse), they will be able to achieve a greater speed (change in momentum) than if they used similar forces in a shorter time interval. Unfortunately, in many human movements there is not an unlimited amount of time to apply forces, and there are several muscle mechanical characteristics that complicate...

Supination NeutralPronation

Frontal plane view of rear-foot motion in the first half of the stance phase of running. The foot lands in a supinated position. The motion of the foot and ankle to accommodate to the surface and absorb shock is called pronation. journal space but places a burden on the kinesiology professional to be knowledgeable about variations in descriptive terminology. The anatomical structure and microstructure of skeletal muscle has considerable functional importance. We will see later that...

Three Mechanical Characteristics Of Muscle

Muscle Force Time Eccentric Concentric

Previously we discussed the passive tension in an MTU as it is passively stretched. Now it is time to examine the tensile forces the MTU experiences in the wide variety actions, lengths, and other active conditions encountered in movement. The force potential of an MTU varies and can be described by three mechanical characteristics. These characteristics deal with the variations in muscle force because of differences in velocity, length, and the time relative to activation. The Force-Velocity...

Qualitative Analysis Of Drop Jumps

Plyometrics are common exercises for improving speed and muscular power movements in athletes. Plyometric exercises use weights, medicine balls, and falls to exaggerate stretch-shortening-cycle muscle actions. Considerable research has focused on drop jumps as a lower-body plyometric exercise for improving jumping ability (Bobbert, 1990). Recent research has shown that drop jump exercise programs can increase bone density in children (Fuchs, Bauer, & Snow, 2001). Qualitative analysis of drop...

Rangeofmotion Principle

One area where anatomical description is quite effective is in the area of the range of If muscles create movement in complex synergies that are adaptable, should kinesiology professionals abandon the common practice of naming muscle groups according to anatomical function (quads knee extensors or calf ankle plantar flexors ) Such an extreme reaction to the complexity of biomechanics is not necessary. This common terminology is likely appropriate for prescribing general strength and...

Fundamentals of Biomechanics and Qualitative Analysis

Newtonian Mechanics For Biomechanics

In Chapter 1 we found that biomechanics provides tools that are needed to analyze human motion, improve performance, and reduce the risk of injury. In order to facilitate the use of these biomechanical tools, this text will emphasize the qualitative understanding of mechanical concepts. Many chapters, however, will include some quantitative examples using the algebraic definitions of the mechanical variables being discussed. Mathematical formulas are a precise language and are most helpful in...

Laws Of Kinetics

Inertia Direction Outline Drawing

Linear kinetics provides precise ways to document the causes of the linear motion of all objects. The specific laws and mechanical variables a biomechanist will choose to use in analyzing the causes of linear motion often depends on the nature of the movement. When instantaneous effects are of interest, Newton's Laws of Motion are most relevant. When studying movements over intervals of time is of interest, the Impulse-Momentum Relationship is usually used. The third approach to studying the...

Coordination Continuum Principle

Biomechanical Principles Volleyball

Many kinesiology professionals are interested in the coordination of movement. Coordination is commonly defined as the sequence and timing of body actions used in a movement. Unfortunately there is no universally agreed-upon definition or way to study coordination in the kinesiology literature. A wide variety of approaches has been proposed to describe the coordination of movement. Some approaches focus on the kinematics of the joint or segmental actions Hudson, 1986 Kreighbaum amp Bartels,...

Center Of Gravity

Biomechanics High Jump Center Mass

A natural application of angular kinetics and anthropometrics is the determination of the center of gravity of the body. The center of gravity is the location in space where the weight gravitational force of an object can be considered to act. The center of small rigid objects pencil, pen, bat can be easily found by trying to balance the object on your finger. The point where the object balances is in fact the center of gravity, which is the theoretical point in space where you could replace...

Principle Of Balance

Diagram Line Gravity Human

We have seen than angular kinetics provides mathematical tools for understanding rotation, center of gravity, and rotational equilibrium. The movement concept of balance is closely related to these angular kinetic variables. Balance is a person's ability to control their body position relative to some base of support Figure 7.13 . This ability is needed in both static equilibrium conditions e.g., handstand on a balance beam and during dynamic movement e.g., shifting the center of gravity from...

Qualitative And Quantitative Analysis Of Vectors

Vastus Medialis Vastus Lateralis Torque

Before moving on to the next kinetic approach to studying the causes of movement, it is a good time to review the special mathematics required to handle vector quantities like force and acceleration. The linear kinetics of a biomechanical issue called muscle angle of pull will be explored in this section. While a qualitative understanding of adding force vectors is enough for most kinesiology professionals, quantifying forces provides a deeper level of explanation and understanding of the...

Neuromuscular Control

Electromyographic Olympic Snatch

The mechanical response of muscles also strongly depends on how the muscles are activated. The neuromuscular control of movement is an active area of study where biomechanical research methods have been particularly useful. This section will summarize the important structures and their functions in the activation of muscles to regulate muscle forces and movement. The Functional Unit of Control Motor Units The coordination and regulation of movement is of considerable interest to many scholars....

The Limitations Of Functional Anatomical Analysis

Emg Turkey Gastrocnemius

Anatomy classifies muscles into functional groups flexors extensors, abductors adductors, etc. based on hypothesized actions. These muscle groups are useful general classifications and are commonly used in fitness education, weight training, and rehabilitation. These hypothesized muscle actions in movements and exercises are used to judge the relevance of various exercise training or rehabilitation programs. This section will show that such qualitative estimations of muscle actions are often...

What Is Biomechanics

Qualitative Biomechanical Dance Analysis

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...

Forcemotion Principle

Gymnast Split Jump

Another way to modify human movement is to change the application of forces. The Force-Motion Principle states that it takes unbalanced forces and the subsequent torques they induce to create or modify our motion. To know what size and direction of force to change, recall that a free-body diagram of the biomechanical system is usually employed. A major limitation of functional anatomical analysis was the limited nature of the forces and structures being considered. We are not in a position to...

Review Of Key Anatomical Concepts

Axis Motion Anatomy Planes Motion

This section reviews several key concepts from human anatomy. A course in gross anatomy macroscopic structures is a typi cal prerequisite for the introductory biomechanics course. This section does not review all the bones, muscle, joints, and terms. Students and kinesiology professionals must continuously review and refresh their knowledge of anatomy. Anatomy describes the human body relative to the anatomical position. The anatomical position is approximated in Figure 3.1. The three spatial...

Qualitative Analysis Human Movement Diagram

Free Body Diagram Volleyball

A free-body diagram of a person quietly standing. The major vertical forces acting on the person gravity and ground reaction force are illustrated, while horizontal forces are small enough to ignore. Figure 2.6. A free-body diagram of a person quietly standing. The major vertical forces acting on the person gravity and ground reaction force are illustrated, while horizontal forces are small enough to ignore. body is our first example of what in mechanics is called a free-body...

Nine Fundamentals Of Biomechanics

Nine Principles Biomechanics

Biomechanists measure all kinds of linear and angular mechanical variables to document and find the causes of human motion. While these variables and studies are extremely interesting to biomechanists, some kinesiology students and professionals may not find them quite so inherently stimulating. Most kinesiology professionals want to know the basic rules of biomechanics that they can apply in their jobs. This section proposes nine such principles of biome-chanics and demonstrates how they...