Kinesiology Chapter 14-21

Speed in swiming depends on...

Stroke length and stroke frequency

Segmental Method

-A highly useful procedure for finding the C of G for someone in action. Technique uses: -A photograph or video frame of the subject. -Involves finding the C of G of each body segment -The position of the C of G points are placed on x and y axes. -Knowledge of the ratio between the individual segment weight and total body weight.

PRINCIPLES RELATING TO THROWING, STRIKING AND KICKING

-Anatomical Principles 1 - Muscles contract more forcefully if they are first stretched. 2 - Unnecessary movements and tension mean awkwardness and fatigue. 3 - Skillful performance can be developed only by practice. 4 - Most efficient type of movement is ballistic. 5 - Appropriate levers should be used.

Multi-Impact Helmet

-Any helmets that are designed for sports involving repeated hits are considered multiple impact helmets. -These helmets absorb impact with soft inner foam that does bounce back after impact.

Strengthening provides...

-Stability -Load handling -Safety

Single Impact Helmet

-helmet must be replaced after a single impact. -Absorb impact with an inner stiff foam material of the helmet.

Anatomical Principles in Walking

1 - Alignment a)Reduces friction and decreases the likelihood of strain and injury. b)Stability of weight bearing limb and balance of trunk over this limb are factors in smoothness of gait. 2 - Unnecessary lateral movements decrease gait economy. a)Excessive trunk rotation with excessive arm motion. b)Pelvis may drop on one side without support. c)Pelvic rotation should be just enough to enable the leg to move straight forward. 3 - Normal flexibility of the joints reduces resistance. a)Tendons of two joint muscles of lower extremity contribute to economy of muscular action in walking. 4 - Properly functioning reflexes contribute to a well coordinated, efficient gait. a)Injury, disease, or substance abuse can interfere with the walking reflexes.

Jumping: Total Height

1 - Distance between the ground and the center of gravity at the moment of take off. 2 - Maximum distance the center of gravity is projected vertically.

ERGOMETER ROWING: 2 Phases

1 - Drive phase 2 - Recovery phase

Mechanical Principles in Jumping, Hopping, and Leaping

1 - For movement to occur, inertia must be overcome. 2 - Use of the stretch-shortening cycle will enhance jump. 3 - Jumpers project themselves into the air by exerting a force against the ground that is larger than the force supporting their weight. 4 - The upward thrust of the arms in the jump accelerates the support leg downward, which causes a reaction from the ground. a)Also raises the center of gravity immediately prior to take off, which may result in increased jump height or distance. 5 - The magnitude of the impulse that the jumper exerts against the ground is a product of the applied forces and the time over which they act. 6 - The path of motion of the center of gravity is determined by the angle at which it is projected, speed of projection, height of the center of gravity at take off, and air resistance. 7 - Angular momentum may be developed by the sudden checking of linear motion or by an eccentric thrust.

Principles Relating to the Point at Which the Force is Applied

1 - Force applied in line with an object's center of gravity will result in linear motion. 2- Force applied not in line with an object's center of gravity will result in rotary motion. 3 - If the free motion of an object is interfered with by friction or by the presence of an obstacle, rotary motion may result, even though the force is applied in line with the object's center of gravity.

2 Primary Strategies on a Continuum

1 - Hip Strategy 2 - Ankle Strategy

Sum of Three Distances

1 - Horizontal distance between take off foot and the line of gravity of performer. 2 - Horizontal distance the center of gravity travels in the air. 3 - Horizontal distance of center of gravity behind body part that lands closest to the take off point.

Mechanical Principles in Running

1 - Inertia must be overcome. The problem of inertia decreases as speed increases. 2 - Acceleration is directly proportional to power in the leg drive. 3 - The smaller the vertical component of ground reaction force the greater the horizontal (driving) component. 4 - The more horizontal force directed straight backward, the greater the contribution to forward motion of the body. 5 - The length of leg in the driving phase should be as great as possible when speed is a consideration. 6 - By flexing the free leg at the knee and carrying the heel high up under the hip, the leg is moved more rapidly & economically. 7 - The force of air resistance can be altered by shifting the center of gravity.

Principles Relating to the Direction of Force

1 - The direction in which the object moves is determined by the direction of the applied resultant force. 2 - If an object is forced to move along a predetermined pathway, any component of force not in the pathway direction is wasted and may serve to increase friction. 3 - When optimum force production is the purpose, segments involved should be aligned with the direction of force production.

Mechanical Principles in Walking

1 - Inertia of the body must be overcome with every step. 2 - A brief restraining action of the forward limb serves as a brake on the momentum of the trunk so as not to move the center of gravity beyond the new base of support. 3 - Translatory movement is achieved by alternating the lower extremity angular motion between the foot (support) and hip (swing) (inverted pendulum). 4 - The vertical component of ground reaction force serves to counteract the pull of gravity. a)The horizontal component serves to: check forward motion during heel strike. produce forward motion during toe off. 5 - Speed is increased by increasing stride length, stride rate, or both. 6 - Speed is directly related to magnitude of force and direction of application. 7 - Efficiency of locomotion partially depends on friction and ground reaction force. 8 - Most efficient gait is one that is timed to permit pendular motion of the lower extremities. 9 - Alternating loss and recovery of balance. 10 - Lateral distance between feet is a factor in lateral stability, with average step width at ~ 10% of leg length.

Three Important Functions of the Sprint Crawl

1 - Minimize Resistance 2 - Enable the swimmer to breath. 3 - Provide a stable anchorage for the arm and leg muscles to effect a maximum propulsive force.

PRINCIPLES OF PUSHING AND PULLING MOTIONS

1 - Motion involves imparting a force, described in terms of its magnitude, direction, and point of application. 2 - These aspects of force provide the basis of the principles that apply to giving motion to objects or bodies through pushing and pulling.

Principles Related to Hanging and Hand Traveling Activities

1 - Muscles of the arm and shoulder girdle must contract to protect the joints. 2 - Hand traveling is a locomotor pattern governed by the principle of action and reaction. 3 - The action used in hand climbing activities is essentially a pull-up action. 4 - Sequential hand support movements should be continuous, so that momentum of one action contributes to the next action.

Principles of Stability

1 - Other things being equal, the lower the C of G, the greater will be the body's stability. 2 - Greater stability is obtained if the base of support is widened in the direction of the line of force. 3 - For maximum stability the line of gravity should intersect the base of support at a point that will allow the greatest range of movement within the area of the base in the direction of the forces causing motion. 4 - Other things being equal, the greater the mass of a body, the greater will be its stability. 5 - Other things being equal, the most stable position of a vertical segmented body is one in which the C of G of each weight-bearing segments lies in a vertical line centered over the base of support. 6 - Other things being equal, the greater the friction between the supporting surface and the parts of the body in contact with it, the more stable the body will be. 7 - Other things being equal, a person has better balance in locomotion under difficult circumstances when the vision is focused on stationary objects rather than on disturbing stimuli. 8 - There is a positive relationship between one's physical and emotional state and the ability to maintain balance under difficult circumstances. 9 - Regaining equilibrium is based on the same principles as maintaining it.

Major Components of Walking

1 - Pelvic rotation 2 - Pelvic tilt 3 - Knee flexion 4 - Hip flexion 5 - Knee and ankle interaction 6 - Lateral pelvic displacement

Principles for Selecting Abdominal exercises

1 - Performer must be able to prevent tilting of the pelvis and hyperextension of the lumbar spine. 2 - Strengthen all abdominal muscles. 3 - Overall spine health will determine positioning of spine and pelvis and need for core strengthening.

Two Distinct Phases Of Rowing...

1 - Pull phase 2 - Recovery phase

Two major types of running

1 - Races 2 - Games and Sports

Reaction Board Method

1 - Relies on the fact that the sum of the moments acting on a body in equilibrium is zero. 2 - The location of the gravitational line is found for each plane. 3 - The C of G is the intersection of the values for each of these three planes. 4 - Limited to the body in a stationary position.

Major factors in the speed of a struck ball:

1 - Speed of incoming ball & striking implement. 2 - Mass of the ball & striking implement. 3 - Elasticity between ball & striking implement. 4 - Direction of ball & implement at impact. 5 - Point of impact between ball & implement.

Mechanical Principles Applied to Swimming

1 - Swimming should produce even progress through the water. 2 - The body will move in the opposite direction to the force applied. 3 - Forward motion is produced through a combination of drag and lift forces. 4 - To produce maximum force present as broad a hand surface as possible during propulsion and exert backward pressure through as great a distance as possible. 5 - Momentum may be transferred from one body part to another body part as momentum is conserved. 6 - The body position in the water depends on buoyancy and speed through the water. 7 - When a body is free in a fluid, movement of a part in one direction results in movement of the rest of the body in the opposite direction. 8 - A rapidly moving body in the water leaves a low pressure area immediately behind it. 9 - The more streamlined the body, the less the resistance to progress through the water. 10 - The drag on a body in any fluid increases approximately with the square of the velocity. 11 - The sudden or quick movement of a swimmer's body, or one of its parts, at the surface of the water tends to cause turbulence that increases drag.

2 Phases of Walking

1 - Swing 2 - Support

Mechanical PrinciplesStriking, Hitting, and Kicking

1 - The direction in which the object moves is determined by direction of force applied. 2 - Momentum is conserved in all collisions. 3 - Any change in momentum in colliding objects is related to force and duration of collision. 4 - The greater the velocity of the approaching ball, the greater the velocity of the ball in the opposite direction after it is struck. 5 - The greater the velocity of the striking implement at contact, the greater the velocity of the struck ball. 6 - The greater the mass of the ball (up to a point) the greater its velocity after contact. 7 - The greater the mass of the striking implement (up to a point) the greater the striking force, therefore the greater the speed of the ball. 8 - The higher the coefficient of elasticity of the ball and of the striking implement, the greater the speed of the struck ball. 9 - The direction taken by the struck ball is determined by four factors: A)Direction of striking implement at contact; B)Relation of the striking force to ball's center of gravity; C)Degree of firmness of grip and wrist at contact; D)Laws of rebound.

Principles Related to Swinging Movements

1 - The movement of a pendulum is produced by the force of gravity. 2 - As the pendulum swings downward, gravity causes its speed to increase; as it swings upward, gravity counteracts its speed. 3 - The upward movement of a pendulum is brought about by the momentum developed in the downward movement. 4 - The potential energy of the pendulum is greatest at the height of the swing and zero at the bottom. 5 - The centripetal force in pendular movements increases as the mass or velocity increases and decreases as the radius increases. 6 - When a pendulum reaches the end of its arc, it reaches a zero point in velocity. 7 - The height of a swing may be increased by lengthening the radius of rotation on the downswing and decreasing it on the up swing. 8 - To increase height, the decrease in radius should be initiated at the moment that the center of gravity of the body is directly under the axis of rotation. 9 - The time taken by the pendulum to make a single round trip excursion (know as its period) is related to the length of the pendulum. 10 - The period of the pendulum is not influenced by its weight. 11 - When a body consisting of two segments reaches the vertical, proximal segment leading on the downswing, the distal segment will accelerate relative and precede the proximal on the upswing (beat swing). 12 - The rotation of the hands about a bar is opposed by frictional forces. 13 - In all mounts involving swinging, the center of gravity must be brought as near as possible to the center of rotation. 14 - In support swings the center of gravity should be at the point of support.

Principles Relating to the Magnitude of Force

1 - The object will move only if the force is of large enough to overcome the object's inertia.The force must overcome not only the mass, but also; a)friction between object and supporting surface. b)resistance of surrounding medium. c)internal resistance. 2 - Force exerted by the body will be transferred to an external object in proportion to the counterforce of the feet against the ground. 3 - Optimum summation of internal force is needed if maximum force is to be applied to move an object. (Maximum number of segments moved through largest ROM.) 4 - For maximum accuracy, the smallest possible number of segments should be used through the smallest possible ROM. 5 - For a change in momentum to occur, force must be applied over time.

Mechanical Principles: Throwing

1 - The object will move only if the force is of sufficient magnitude to overcome the object's inertia. 2 - The pattern and range of joint movements depends on the purpose of the motion. 3 - Force exerted by the body will be transferred to an external object in proportion to the counterforce of the feet against the ground. 4 - Linear velocity is imparted to external objects as a result of angular velocity of the body segments. 5 - Optimum summation of internal force is needed if maximum force is to be applied to an object. 6 - For a change in momentum to occur, force must be applied over time. 7 - Force applied in line with an object's center of gravity will result in linear motion of the object. 8 - If the force applied to object is not in line with it's center of gravity, it will result in rotary motion of the object.

Principles Related to Nonsupport Activities

1 - The path of motion of the body's center of gravity in space is determined by the angle at which it is projected into space, the force of the projection, and the force of gravity. 2 - The time a body remains unsupported depends on the height of its projection, which is governed by the vertical velocity of the projection. 3 - Most rotary movements are initiated before the performer leaves the supporting surface 4 - The angular momentum of an unsupported body is conserved. 5 - When a body is free in space, movement of a part in one direction results in movement of the rest of the body in the opposite direction. 6 - A performer who is rotating about a horizontal axis in the air may initiate a twist about a vertical axis by tilting the body to one side.

Principles Applied to Posture

1 - The weight-bearing segments of the body are so aligned in good standing posture that the trunk and in the pelvic girdle are neutral (lack of either posterior or anterior tilt) and maintain normal spinal curves. 2 - In a static posture the line of gravity will be close to the geometric center of the base. Maximum stability usually occurs when the line of gravity is over the center of pressure. 3 - Standing posture is extension of the weight-bearing joints, not be accompanied by strain or tension 4 - Efficient posture would be a position that requires a minimum expenditure of energy for maintenance of alignment. 5 - Efficient posture requires a minimum of muscle force. This implies adequate antigravity musculature to resist the pull of gravity maintain alignment without excessive effort or tension. 6 - Posture requires sufficient flexibility in the weight-bearing joints to permit good alignment without strain. Flexibility should not be so great that excessive muscular effort is needed to keep the weight-bearing joints in alignment. 7 - Posture requires coordination. This implies neuromuscular control and well-developed postural reflexes. 8 - Adjustments in posture can be made more readily with good kinesthetic awareness of posture and muscle tension. 9 - The characteristics of normal posture change with age. Young children typically have a protruding abdomen and hollow lower back. Older persons show a wider stance, forward head and rounded upper back, and limited flexibility in the trunk, hips, and knees.

The magnitude of force used in pushing, pulling, and lifting can be increased in two ways:

1 - Using the lower extremities. 2 - Using body weight to supplement the force provided by the upper extremities.

The goal of most protective equipment is to...

1 -Take a blow from a relatively small point of contact and dissipate or distribute that force over a greater surface area 2 - use a compressible material to dissipate/absorb the shock of the impact.

Body will reach terminal velocity between ____ to ____ mph

100 to 200 mph

If the weight in the backpack exceeds ________ of body weight changes in gait and posture will occur.

20%

Females Center Of Gravity...

55% of standing height

Males Center Of Gravity....

57% of standing height

Isotonic Exercise

A combination of the terms "constant" and "tension".

Active Stretching

Antagonists are stretched by concentric contraction of contralateral muscles.

Momentum-impulse relationship:

Any change in momentum requires a force applied over a period of time (impulse) and is equal to the product of the force and the time.

Problems in receiving impact:

Avoiding injury. Maintaining equilibrium. Receiving the object with accuracy and control.

Suspension Activities

Climbing, hanging, swinging

Proprioceptive Neuromuscular Facilitation (PNF) Stretching

Combinations of sustained static stretch and muscular contraction.

Plyometrics

Eccentric contraction immediately followed by explosive concentric contraction, takes advantage of stretch reflex and elastic components of muscle.

Isokinetic Exercise

Exercise at a constant speed.

Basic Joint Actions

Flexion and Extension

The Kick That Is Most Often Used Is The...

Flutter Kick

Rowing: Pull Phase

Force applied to the water by the oar blade.

Bicycle: Magnitude of force depends on

Gear Ratio

HECC

Hockey Equipment Certification Council -HECC's Mission is to seek out, evaluate and select standards and testing procedures for hockey equipment for the purpose of product certification.

Lateral movements of the trunk will _______ resistance to forward movement

Increase

Isometric Exercise

Involves no change in muscle length.

Rowing: Much of the propulsive force is generated by the ____

Legs

Actions of the arms and legs result in a combination of what two forces that propel the body forward?

Lift and Drag

Eccentric Exercise

Makes Muscle Longer While Doing Work

Sequential Movements

Movement of body segments resulting in the production of summated velocity at the end of the kinetic chain of segments.

Stable Equilibrium

Occurs when an object is placed in such a fashion that an effort to disturb it would require its C of G to be raised.

Passive Stretching

Requires the help of another person or gravity.

Center Of Gravity

The "balance point" of the body. The point where the weight of the body acts.The point where all forces acting on the body equal zero: -Linear forces must be balanced. -Torques must be balanced.

LOCOMOTION

The act or power of moving from place to place by means of one's own mechanisms or power. In the human being, it is the result of the action of body levers propelling the body.

Pressure-area relationship:

The pressure that any part of the body must absorb is inversely proportional to the area over which the force is applied.

Factors Affecting Stability

Three primary factors: 1 - Size of the base of support. 2 - Relation of the line of gravity to the base of support. 3 - Height of the center of gravity

Core

Vertebral column and its' supporting structures and musculature.

Kinetic energy-work relationship:

When a body or object is "received" work is done equal in amount to the change in kinetic energy of the moving body.

Neutral Equilibrium

When a object's C of G is neither raised nor lowered when it is disturbed.

Unstable Equilibrium

When a slight disturbance will drop the objects' C of G to a lower point.

Overload

a muscle must be exercised beyond its normal limits in order to improve strength or endurance.

Flexibility

ability of the tissues surrounding a joint to yield to stretching without interference or opposition and then to relax.

Muscular Endurance

ability to perform repeated contractions against a submaximal resistance.

Ballistic Stretching

active bouncing, uses momentum to stretch tissues.

Rectilinear path:

all forces are applied directly to the object in the direction of motion.

Location of Center of Gravity depends on...

body build, age, and sex.

Running: Stride Length

determined by length of leg, ROM of hip, and power of leg extensors.

Running: Stride Rate

determined by speed of contraction and skill of performer.

Stride Length

distance covered in one stride.

Muscular Strength

force a muscle can exert against a resistance in one maximum effort.

Turbulence

forms behind the body

Step

from heel strike of one leg to heel strike of opposite leg.

Stride

from heel strike to the next heel strike of the same leg.

Posture

implies shape or configuration of the body

Static Stretching

gradual stretching up to the point of discomfort, and hold for a minimum of 30 sec.

Concentric Exercise

involves lifting free weights or stack weights.

Momentary Contact:

striking and kicking.

Running: Speed is governed by ____

length and frequency of stride.

Factors responsible for rotary locomotion are:

magnitude, direction, and accurate timing of the forces contributing to the desired movement of the body, including advantageous use of the force of gravity whenever possible.

Wave Drag

occurs at the surface as the body moves along

Center of pressure

point at which the force vector for ground reaction force is applied.

Walking relies heavily on ____

reflex

Form Drag

resistance due to surface area of the front of the body

Surface Drag

resistance of the water next to the body.

Speed on a Bike is determined by:

slope, gear ratio and pedal cadence.

Running: Speed Is The Product of ___

stride duration and stride length.

The brief moment between entry and the beginning of the propulsive action is called the ______

support phase

Jump

take off from one or both feet and land on both feet.

Leap

take off is from one foot and landing is on the other foot.

Stroke Frequency Depends On...

the amount of time spent per stroke cycle

The greater the mass,

the greater the stability.

Repetition maximum (RM)

the resistance a muscle can lift a given number of times.

Hop

the same foot is used for the take off and landing.

Projection: throwing

throwing

Progressive Resistance

training must be increased as adaptations are acquired in order to continue to use overload. Increase up to 10% when load becomes easy.

Specificity

training must be specific to meet the demands of an activity.