# Biomechanics/KYU

 Work in progress, expect frequent changes. Help and feedback is welcome. See discussion page.

Sports and Exercise Biomechanics

# course outline

1. Introduction to sports biomechanics concepts and their application to movement
2. Importance and functions of sports biomechanics
3. Axes and planes of the body
4. Range of body motions (ROM)
5. Forces and their application in sports
6. Linear and angular types of Motion and their determinants
7. Human muscle
8. Weight and movement
9. Friction
10. Impulse
11. impact and application to various sporting situations
12. Energy and uses of energy to perform work
13. Concepts of body power
14. Strength
15. Efficiency in sports movement

# Definition

The science that deals with an athlete’s movement whilst also considering the internal and external forces that are in effect whilst performing any desired movement

# Introduction

You are probably planning a career as a PE teacher, coach, or some other physical activity specialist, and you probably are or have been active as a participant in one or more sports or fitness activities. Suppose a student or athlete asks you why should I do this skill this way or why isn’t this technique better?. Perhaps you even asked such questions when you were a student or athlete. Was the coach or teacher able to answer your question? Were you asked these questions? Could you answer them?. Traditional teaching and coaching tell you what techniques to teach or coach, where as biomechanics tells you why those techniques are the best to teach or coach

# Importance of Biomechanics

Biomechanics includes the study of all living things, plant, animal; animal biomechanics includes only animals as subjects of study; human biomechanics includes only humans; and sport biomechanics includes only humans involved in exercise and sport. We might define exercise and sport biomechanics as the study of forces and their effects on humans in exercise and sport.

   Performance Improvement'


The ultimate goal of exercise and sport biomechanics is performance improvement in exercise or sport. A secondary goal is injury prevention and rehabilitation. This secondary goal is closely related to the first and could almost be considered part of the primary goal, because an uninjured athlete will perform better than an injured athlete.

   Technique Improvement


The most common method for improving performance in many sports is to improve an athletes technique. This is one of the motivating factors for studying biomechanics. The application of biomechanics to improve techniques may occur in two ways; Teachers and coaches may use their knowledge of mechanics to correct actions of a student or athlete in order to improve the execution of a skill, or a biomechanics researcher may discover a new and more effective technique for performing a sports skill. In the first instance, teachers and coaches use qualitative biomechanical analysis methods in their everyday teaching and coaching to effect changes in technique. In the second instance a biomechics researcher uses quantitative biomechanical analysis methods to discover new techniques, which are then communicated to teachers and coaches to implement them

   Equipment Improvement


How else can biomechanics contribute to performance improvement? What about improved designs for the equipment used in various sports? Shoes and apparel(sports cloth) constitute the equipment used in almost every sport. The equipment worn may have an effect on the performance, either directly or through injury prevention. Besides shoes and apparel, many sports require the use of some sort of implement. Think of sports in which an implement is used in your institution. How have changes in sports implements changed performances in these sports? What about bicycling, swimming, tennis, golf, hockey, high jump, javelin throwing, soccer, basketball, etc. Lighter and better-designed implements have not only contributed to improved performances by elite athletes in these sports, they have contributed to improved performances by recreational participants as well.

    Training Improvement


Biomechanics has the potential of leading to modifications in training and thus improvements in performance. This application of biomechanics can occur in several ways. An analysis of the technique deficiencies of an athlete can assist the coach or teacher in identifying the type of training the athlete requires to improve in performance. The athlete may be limited by the strength or endurance of certain muscle groups, by speed of movement, or by one specific aspect of his/her technique. Sometimes, the limitation may be obvious. For example a gymnast attempting an iron cross maneuver requires tremendous strength in the adductor muscles of the shoulder. A mechanical analysis of the maneuver would reveal this, but it is already obvious to gymnastics coaches and observers. In other sport skills, the strength requirements may not be so obvious.

    Injury prevention and rehabilitation


Some believe that injury prevention and rehabilitation should be the primary goal of exercise and sport biomechanics. Biomechanics is useful to sports medicine professionals in identifying what forces may have caused an injury, how to prevent the injury from recurring (or occurring in the first place), and what exercises may assist with rehabilitation from the injury. Biomechanics can be used to provide the basis for alterations in technique, equipment, or training to prevent or

   rehabilitate injuries.
*Techniques to reduce injury


*Equipment designs to reduce injury

# Friction

Friction can either be dry friction also referred to as coulomb friction or fluid friction, which is developed between two layers of fluids and occurs when dry surfaces are lubricated. The behaviour of fluid friction is complicated, and because it occurs less frequently in sports, we will limit our discussion to dry friction. Dry friction acts between the non-lubricated surfaces of solid objects or rigid bodies in contact and acts parallel to the contact surfaces. Friction arises as a result of interactions between molecules of the surfaces in contact. When dry friction acts between two surfaces that are not moving relative to each other, it is referred to as static friction (also referred to as limiting friction when describing the maximum amount of friction that develops just before two surfaces begin to slide). When dry friction acts between two surfaces that are moving relative to each other, it is referred to as dynamic friction (also referred to as sliding friction or kinetic friction).

Friction and Normal Contact Force Adding books to a pile increases the inertia of the pile by increasing its mass. This shouldn’t affect the static friction force, though, because there is no apparent way an increase in mass could affect interactions of the molecules of the contacting surfaces, it is these interactions that are responsible for friction. The weight of the pile was also increased by the added books, increasing the weight increases the normal contact force acting between the two surfaces. This would increase the interactions of the molecules of the contacting surfaces, because they would be pushed together harder, so it is not the weight of the books that caused the increase in static friction force, but the increase in the normal contact force. If the normal contact force and the friction force are measured, the friction force is proportional to the normal contact force, as one increases, the other increases proportionally. This is true for both static and dynamic friction. In this case,the friction force is horizontal, and the normal contact force is a vertical force influenced by the weight of books.

# Motion

We might define motion as the action or process of change in position. Movement is a change in position. Moving involves a change in position from one point to another. Two things necessary for motion to occur;

• Space (space to move in)
• Time (time during which to move)

Movements are classified into

     #linear,
#angular or both (general)