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The Kinesiology of a Lacrosse Shot

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Rachel Novario

on 6 May 2014

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Transcript of The Kinesiology of a Lacrosse Shot

Phase 4: Stick Deceleration
Stick deceleration begins once the ball release has occurred and ends when the elbow of the top arm has reached maximum extension.
Phases of The Crank-Back
Phase A
Begins when the foot of the drive leg contacts the ground and ends when the foot of the lead leg contacts the ground. This phase could also be described as a ‘drive step’ when focusing on the lower extremity.

What Is Lacrosse?
Men’s lacrosse is a team field sport played with 10 players per side on a field 110 yards long.
Players attempt to gain possession of the ball in their sticks and advance it down the field either by running or passing in an effort to shoot the ball into the opposing team’s goal.
The ball is held in the webbing of the stick, or “crosse,” at the end of a metal shaft. Offensive players use sticks that are 40 inches (1 m) in length, while defensemen may use a stick that is up to 6 feet (1.8 m) in length.
Phase 3: Stick Acceleration
Stick acceleration begins when the elbow of the top arm has reached maximum flexion and then starts extending. This phase ends with ball release. The duration of this phase is very short and dynamic.
The Kinesiology of a Lacrosse Shot
Phase 1:
The Approach

Phase 2: The Crank-Back
During this phase, the player is taking several steps advancing towards the goal with the intent to shoot.
The number of steps, the style of the approach (e.g., stepping forward, sideways, backwards, cross-over, hopping, etc.), and the velocity of the approach varies between players.
What is common among all approach styles is that it ends when the drive leg contacts the ground.
Lacrosse involves a complex rotary motion entailing a kinetic linking from your feet to your arms. Kinetic linking is associated with kinetic energy. Kinetic energy is “the form of energy contained in an objects motion” (Bloomfield, 31).
Movement
Each body segment is a “link in the chain” (i.e. hips, arms, stick, etc.). In preparation for just the right shot, a good player needs to understand the basic rotary mechanics, the first link in the chain.
The initiation of the shooting motion begins in the lower body, one needs to have the ability to create a pelvic torque. It starts from the bottom and works its way up.
When you add gravity, momentum, body rotation, and stabilization together, torque is your ending result.
The approach begins with the player initiating movement and ends when the foot of the drive leg contacts the ground.
The crank back is the same as the wind-up or cocking phase of throwing a ball.
This phase consists of the preparatory movements that proceed accelerating the stick (angular motion) with the intent of releasing the ball towards the goal.
The crank back begins with the foot of the drive leg contacting the ground and ends when the top arm reaches maximum elbow flexion.
Phase B
Begins with lead foot contact and ends when the elbow of the top arm reaches maximum flexion. The movements in this phase are still preparatory movements to accelerating the stick towards the goal and would still be considered ‘wind-up’ movements.

Phase 5: The Follow-Through
The follow-through phase begins when the top arm has reached maximum extension and ends when trunk rotation has been terminated.
Recovery. The recovery phase begins with the end of trunk rotation and represents the movements the player needs to make to prepare for the next task.
Newton's First Law
Inertia
An object at rest tends to stay at rest and an object tends to stay in motion unless acted upon by an outside force.
Example
A lacrosse ball will not stop besides when acted upon by gravity and air resistance
Newton's Second Law
Force= Mass x Acceleration
Example
The force of a ball in the air is equal to the mass of the ball time the acceleration of the ball
Newton's Third Law
Equal and opposite forces; for every action there is an equal and opposite reaction
Example
When catching a ball, you must use the same amount of force to catch the ball as it is coming at you
Shooting
When shooting, your stick and arms act as a series of levers.
The top hand pushes a force on the shaft. The bottom hand pulls a force back on the shaft. This creates a lever with you arm and shaft. Your top hand is the fulcrum.
A player maximizes the power of his shot by as he drives his foot into the ground it allows him to convert his linear momentum from the run up to the shot into rotational momentum.
A player conserves this momentum through his hips and torso. A player usually rotates their shoulders of 1,000 degrees per second during a shot.
By pivoting the stick through your upper hand, creating force in both the upper and lower hands, you generate large torque forces and throw the ball great distances.

Displacement
The shortest distance between the starting point of a moving object and its final point.
When talking about displacement in a lacrosse shot a ball is usually shot in a straight line with little change in vertical height.
The displacement will essentially be equal to the distance.
Distance
The total amount of space covered by a traveling object, from its initial starting point to its destination.
Distance depends on the path that the object takes.
With a lacrosse shot the distance the ball travels and the total displacement of the ball may perhaps be the same because the path the ball takes is almost a straight line.

Speed
The rate at which an object covers distance.
Speed is a scalar quantity, which means that the quantity is fully described by a numerical value alone and does not need a direction.
Speed of the ball shot from the stick into the net.

Velocity
The rate of change of position of an object, equivalent to its speed with a direction of motion added.
Velocity is a vector quantity so the direction of motion must be added.
To find this we would have to take the distance from the net divided by the time the ball takes to reach the net and add direction of motion.

Acceleration
Defined as the rate at which an object changes its velocity. So if an object is accelerating then its velocity is changing.
Acceleration is a vector quantity, and is calculated through the change in velocity divided by the change in time.
The ball will start at a velocity of zero. So the final velocity subtracted by the initial velocity divided by the amount of time the ball takes to hit the net ail give us the balls acceleration.
Paul Rabil
Sport Science:
Paul Rabil
Injuries
Men’s lacrosse is sometimes perceived to be a violent sport, but injury statistics do not support this claim. For the past 20 years, the National Collegiate Athletic Association (NCAA) has maintained prospective injury surveillance data on inter-collegiate lacrosse programs.
Reviewing the available literature, certain trends have consistently been observed.
Most injuries above the waist occur from direct trauma. These occur either from a collision with another player, or as a result of impact from a stick check or thrown ball.
In contrast, lower extremity injuries often occur from non-contact mechanisms, such as pivoting or twisting. Approximately 40% of lacrosse injuries are non-contact.
According to the NCAA, the body parts most frequently injured were the ankle, upper leg, and knee, which combined accounted for 48% of the injuries
Despite the fact that injuries are fairly common, they generally are minor and rarely require surgical intervention.
Risk Factors for Injury
Anatomical factors include individual physical characteristics including: gender, height, weight, age, Q-angle, and medical history.
Research has examined the clinical significance of biomechanical movements as potential risk factors.
These risk factors may influence the forces applied and increase the risk of injury to the lower extremity during dynamic tasks such as abrupt starts and stops, pivots, and side-cutting
The Shoulder Joint
1. Traps- Eccentric
2. Teres major- Eccentric
3. Deltoid- Posterior: Eccentric, Anterior: Concentric
4. Triceps- Eccentric
5. Latissimus dorsi- extension of the humerus: Eccentric
Secondary Muscles/Stabilizers/Neutralizers

1. Pectoralis: Concentric
3. Rotator cuff- teres minor and infraspinatus: Eccentric
4. Biceps- rapid acceleration of arm extension. Serves as an antagonist in the shooting action: Eccentric
Primary Muscle Movers Lever Classification
Class III Lever- effort placed between the load and the fulcrum
Length/Tension Relationship
Degrees of Freedom
There are 5 degrees of freedom at the glenohumeral joint
1. Flexion/extension
2. Abduction/adduction
3. Internal/external rotation
4. Circumduction
5. Horizontal abduction/adduction
Plane of Motion and Associated Axis
The glenohumeral joint moves in the transverse plane, which is associated with the longitudinal axis
Primary Muscle Movers
and Contraction Type
The Elbow Joint
Degrees of Freedom
1. Flexion/ Extension

Primary Muscle Movers
and Contraction Type
1. Biceps: Eccentric
Primary Muscle Movers Lever Classification
The elbow is considered to be a Class I Lever (Resistance, AXIS, Effort)
Secondary Muscles/Stabilizers/Neutralizers
1. Brachioradialis: Eccentric
Length/Tension Relationship
The biceps brachii is a two-joint muscle. It is involved in both elbow and shoulder flexion. During the shooting motion, the elbow could experience active insufficiency if the elbow or shoulder is fully flexed. For example, full flexion at the shoulder joint would limit FROM/full extension at the elbow joint.
The Wrist Joint
Degrees of Freedom
1. Flexion/Extension
2. Radial/Ulnar Deviation
3. Pronation/Supination
Primary Muscle Movers
and Contraction Type
1. Wrist Flexors (flexor carpi radialis, flexor carpi ulnaris, palmaris longus): Concentric
Primary Muscle Movers Lever Classification
Secondary Muscles/Stabilizers/Neutralizers
1. Wrist Extensors (Extensor carpi ulnaris, extensor carpi radialis longus and brevis): Eccentric
Length/Tension Relationship
If an athlete has improper form during a shot, excess stress can be placed on the wrist.
Repeated excess stress can lead to a loosening of the retinaculum around the wrist, along with the stabilizing ligaments.
This overuse leads to a strain on the elastic component of the joint, thus decreasing efficiency and power during wrist flexion and extension. Over time, this could negatively impact a player's shot and velocity.
The Hip Joint
Degrees of Freedom
1. Flexion/Extension
2.Adduction/Abduction
3. External/Internal Rotation
Primary Muscle Movers
and Contraction Type
1. Rectus and transversus abdominis: Concentric
2.Internal and external obliques:
Concentric
3. Erector spinae:
Concentric
4. Quads: Concentric
5. Hamstrings: Eccentric
Primary Muscle Movers Lever Classification
The hip is considered to be a Class III lever
Secondary Muscles/Stabilizers/Neutralizers
1. Glute Max: Stabilizer, Isometric
2. Hip flexors (Psoas Major, Illiacus): Isometric
Length/Tension Relationship
The muscles of the hamstrings (semitendinosus, semimembranosus, and the long head of biceps femoris) all act as two joint muscle. The rectus femoris also acts as a two joint muscle, crossing the hip and knee joints.
Because they are two joint muscles, it is possible that they would experience active insufficiency during the shooting motion. This can lead in a decrease in performance in regards to shot speed, force, and accuracy.
Degrees of Freedom
1. Flexion/Extension
2. Screw Home Mechanism (Rotation)
Primary Muscle Movers
and Contraction Type
1. Hamstrings: Eccentric
2. Quads: Concentric
Primary Muscle Movers Lever Classification
The knee is considered to be a Class III lever. A class 3 lever is produced when a load (leg) moves both a greater distance and more quickly than the effort ( muscle contraction). Also, the effort is applied between the fulcrum (knee) and the load (leg).
Secondary Muscles/Stabilizers/Neutralizers
1. Sartorius (Twisting motion): Concentric
Length/Tension Relationship
The biceps and rectus femoris can experience active insufficiency during the shooting motion because it crosses both the hip and knee joint. If the hip is fully flexed, the knee will not be able to fully extend at the same time. This is an example of active insufficiency during the shooting motion.
The Knee Joint
Degrees of Freedom
1. Plantar Flexion/Dorsi Flexion
Primary Muscle Movers
and Contraction Type
1. Gastroc: Eccentric
2. Anterior Tib: Concentric

Primary Muscle Movers Lever Classification
The ankle joint is considered to be one of the very few Class II levers in the body.
Secondary Muscles/Stabilizers/Neutralizers
1. Soleus: Eccentric
Length/Tension Relationship
The gastroc could experience active insufficiency during the shooting motion. It crosses the knee and ankle joint, so when the multi-joint muscle reaches a length where it can no longer apply effective force, the muscle experiences active insufficiency.
The gastroc is active in both knee flexion and plantar flexion.
The Ankle Joint
Works Cited
http://www.healio.com/orthopedics/journals/ortho/%7B589216dd-bc64-4749-8aed-d22ccf9089a0%7D/injuries-in-mens-lacrosse
http://www.adrln.com/blog/how-to-increase-your-shot-speed/
http://www.e-lacrosse.com/yeager2.html
-The force load applied at the shoulder during the Approach Phase changes the elastic mechanical properties of the shoulder muscles.
-In general overhead athletes have reduced end point stiffness due to joint laxity caused by the biomechanics of their overhead sport.
Planes and Axis of Rotation
1. Sagittal plane along mediolateral axis: flexion/extension
2. Frontal plane along anterioposterior axis: abduction/adduction
3. Transverse plane along longitudinal axis: external/internal rotation
http://kinesiology.wikispaces.com/lacrosse_fitness
http://thesportjournal.org/article/description-of-phases-and-discrete-events-of-the-lacrosse-shot/
http://digitalscholarship.unlv.edu/cgi/viewcontent.cgi?article=2865&context=thesesdissertations
Plane of Motion and Associated Axis
The elbow moves in the sagittal plane along a mediolateral axis.
Plane of Motion and Associated Axis
1. Flexion/Extension: Sagittal plane along mediolateral axis
2. Radial/Ulnar Deviation: Frontal plane along anterioposterior axis
3. Pronation/Supination: Transverse
Plane of Motion and Associated Axis
The wrist is considered to be a Class III Lever
1. Flexion/Extension: Sagittal plane along a mediolateral axis
2. Screw Home Mechanism (Rotation) along a transverse plane
Plane of Motion and Associated Axis
1. Plantar/Dorsi Flexion occurs in the sagittal plane along the mediolateral axis

The hamstrings experience this same active insufficiency during knee flexion and hip extension.
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