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Muscle analysis of the shoulder:

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Kaitlyn Naumik

on 12 December 2013

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Transcript of Muscle analysis of the shoulder:

Muscle analysis of the shoulder:
Drawing back a compact bow

Background of a compact bow
Unlike traditional bows which can be drawn back practically any distance, compound bows are engineered to draw back only so far - and then stop.
This distance is called the "Draw Back Length"
You need to match your "Draw Length" to the bows "draw length"
Draw Weight- is the peak amount of weight an archer will pull while drawing the bow.
you want to what is comfortable
Rule of thumb is you want to use 75% of your maximum strength.
Muscle activity during the draw back
The primary archery muscles are:
rotator cuff muscle group,
teres minor
The accessory muscles in the back are:
rhomboids major and minor,
levator scapulae
latissimus dorsi.
Why did we choose this activity?
Injuries that happen with this movement can affect day to day life for someone who participates in this activity
This activity can help strengthen the shoulder and may benefit the person in other sports.
Chase is a state champion in archery.
Could there be a correlation between males who hunt and play baseball?
Kaitlyn has recently picked up the hobby
PT's might see this in the older male population since we do life in the south.
We love the Hunger Games as well.
Very Small Child (55-70 lbs.) 10-15 lbs.
Small Child (70-100 lbs.) 15-25 lbs.
Larger Child (100-130 lbs.) 25-35 lbs.

Small Frame Women (100-130 lbs.) 25-35 lbs.
Medium Frame Women (130-160 lbs.) 30-40 lbs.
Athletic Older Child (Boys 130-150 lbs.) 40-50 lbs.

Small Frame Men (120-150 lbs.) 45-55 lbs.
Large Frame Women (160+ lbs.) 45-55 lbs.
Medium Frame Men (150-180 lbs.) 55-65 lbs.
Large Frame Men (180+ lbs.) 65-75 lbs.

Recommended draw weight
Back Tension muscles
The Rhomboids Major and Minor:

primary back tension muscles
movement of these muscles retracts and moves the scapula into downward rotation
pulls the shoulder back towards the spine
Levator Scapula:
Adds in scapular downward rotation
contracts and pulls the shoulder girdle back toward the spine.
Retraction of the scapula.
Latissimus Dorsi:
During the drawing motion aid the posterior deltoid in extending the drawing arm backward and also rotating the arm inward.
On the side of the bow arm, the lats help the middle deltoid stabilize the bow arm into the shoulder joint for increased stability.
The Rotator Cuff Muscles
Back muscles involved with draw back of the bow
How to strengthen these muscles
Rotator cuff exercises
Bend forward at waist.Support weight with “good” arm on table. Lightly swing “bad” arm in small circles (clockwise and counter-clockwise). Keep “bad” arm completely relaxed. Do two sets of 10 repetitions, twice a day.
Begin with the arms comfortably at the sides. Bend elbows at 90 degrees. Squeeze shoulder blades together. Imagine you are trying to squeeze a pencil between your shoulder blades. You may do this exercise on a seated row machine with light resistance.
Lie on side with arm resting on stomach and a small rolled up towel under the arm. Slowly rotate arm upwards and stop when forearm is in a position just above horizontal. This exercise can be initiated using a 2-3 pound dumbbell
Lie on stomach with arm hanging over side of table and the thumb facing forward. Slowly raise arm straight out to the side and stop when arm is parallel to the body.
PRONE ELEVATION in the plane of the Scapula
Begin in the same position as in the exercise above, except rotate your hand so the thumb is rotated 45° out to the side. Slowly raise arm in a plane 45° forward and stop arm just below parallel to the body.
The posterior deltoid is used in extending the arm backward and is one of the most important muscles used in pulling the bow back to full draw.
The middle deltoid lifts the arm out to the side. It is the primary muscle that holds the bow arm straight and steady during full draw.
The anterior deltoid helps to raise the arm forward and is used in the initial phase of lifting the bow arm.
Deltoid Exercise
Anterior Deltoid
anterior arm raises with weight
Medial Deltoid
Lateral raises with weight
Posterior Deltoid
Upright row, seated reverse flys
They hold and stabilize the arm when it is extended (during the movement in the draw back motion)
The infraspinatus and teres minor are external rotators of the arm and aid the drawing arm in rotating slightly outward during the draw phase.
The supraspinatus, along with the middle deltoid, lift the arm out to the side of the body. It also pulls the head of the humerus or ball of the arm into the shoulder socket.
This motion allows the bow arm to "lock" into the shoulder joint for increased stability while holding the bow at full draw.
Prevention of Injury
Common injuries in bow hunters
Shoulder injuries (including rotator cuff) 47%
shoulder impingement
muscle strain
Rotator Cuff tear
archer's shoulder occurs when the shoulder itself becomes dislocated as a repetitive stress injury, resulting in pain and shoulder instability.

shoulder shrugs
lat pull downs
Application of professional use
Complicated joint, so if you know the major muscles involved, you can help the athlete to perform at their highest potential.
In PT or AT, if working with younger and older population, shoulder injury is a common site of injury.
An injury from this hobby can crossover into other sports or activities of daily living
Prone Row with External Rotation
Begin in the same position as above, except rotate your hand so the thumb is facing towards the body. Perform a rowing motion with the elbow in the same plane as the shoulder, and stop when the elbow is even with the shoulder. After achieving this position, rotate the arm upwards until the forearm is just below parallel with the body.
External Rotation with Thera-tubing (surgical tubing)
Stand while holding the tubing across your abdomen, with a rolled towel between your arm and body. Slowly rotate arm out to side until hand is pointing straight forward, and hold for 3 seconds. Slowly return to start position.
Horizontal Abduction with Thera-tubing
Stand facing toward the attachment site of the tubing, with the arm extended straight out in front of you. Slowly pull arm backwards and out to the side, keeping the arm at shoulder height.
Rows with Thera-tubing
Hold ends of tubing in each hand. Perform rowing motion backwards, keeping elbows elevated at least 60° away from body. When elbows are approximately ½ of the way to the body, complete the motion by pinching the shoulder blades together
-Static or Dynamic:
Drawing a bow is a dynamic force.
There are unequal forces acting acting on the arm when drawing the bow string back.
Initially it is very difficult to draw the bow string back it gets easier as the bow string gets longer because the resistive force lessens.
Law of reaction: For every action there is an equal and opposite reaction.
When the flexor muscles of the arm contract, they exert a force on the bow string.
After the bow string is released the force transfers to the string causing it to contract and accelerate in the opposite direction of the force from the arm.
Newton's First Law
Law of inertia:
A body in motion (or at rest) stays in motion (or rest) unless acted on by and outside force
The bow string applies a force to the arrow when it is released. Once the arrow is released it will travel in a parabolic pathway with forces such as lift, drag and gravity acting on it.
Newtons Second law
-Law of acceleration:
change in acceleration occurs in the same direction as the force that caused it, and change is directly proportional to force causing it and inversely proportional to the mass of body.
The string applies a force to the arrow causing it to accelerate at a given velocity.
As the arrow approaches the target it begins to decelerate due to outside forces acting on it.

Newtons third law
Any Questions???
Force is placed between axis and resistance
Axis (A)- Glenohumeral joint
Force (F)- Flexor muscles of arm
Resistance (R)- Bow string
Third Class Lever:
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