When describing joint movement, a
reference position is needed. This position is termed the anatomic
reference position. This position entails: an erect standing position
with the feet slightly separated, the arms hanging by the side, the
elbows straight, and with the palms of the hands facing forward.
Planes of Movement
The following planes are described relative to the median plane, which bisects the body vertically at the navel, dividing the body exactly into left and right halves.
A sagittal plane is any plane parallel to the median plane and divides the body into unequal right and left halves. Moving your arms in forward, in front of you is in the sagittal plane. The sagittal plane is used when an athlete throws their arms forward off the starting block.
A frontal plane is a vertical plane at a right angle to sagittal plane. If you draw a line from one ear to another from above the head and then divide the whole body along this line, the plane formed will be a frontal plane. If you made a snow angel or perform an outsweep in breaststroke you'd be moving in the frontal plane. It is also known as coronal plane.
A transverse plane is a horizontal plane of the body and cuts the body between top and bottom halves. It is perpendicular to both frontal and sagittal plane. The catch phase in freestyle utilizes the transverse plane.
Any plane other than the above-described planes will be an oblique plane.
Anything situated near or towards the front. When a swimmer is in the catch phase of freestyle, their arm is anterior to their body.
Anything situated near or towards the back. During the recovery of freestyle, a swimmer’s arm is posterior to their body.
Anything situated near or towards the head. When the swimmer's hand enters the water it is superior to their body.
Anything situated near or towards the feet. If the swimmer pulls downward during the catch, their hand is moving inferior or towards the feet.
Anything situated near or towards the center. If during the catch phase the swimmer moves towards the body, like a cross over catch, then their arm is moving in the medial plane (near the middle of the body).
Anything situated near or towards the outside. During the recovery phase of freestyle, if the swimmer's arm is wide it is moving away from the middle of the body laterally.
Anything situated near or that is coming closer. In freestyle, if the swimmer demonstrates a shallow catch then their hand is proximal or near their trunk.
Anything situated or moving away. If the swimmer pulls deep during the catch phase of freestyle, then their arm is distal (away from the trunk).
Movement educed by muscle.
Start of a muscle.
End of a muscle.
Joints and Movement
The shoulder consists of four main joints: sternoclavicular, glenohumeral, scapulothoracic, and acromioclavicular. These joints allow remarkable ranges of motion in several planes of movement.
Retraction (adduction) Scapula
The scapula is moved posteriorly and medially along a transverse plane, moving the arm and shoulder joint posteriorly. Retracting both shoulder blades gives a sensation of “squeezing the shoulder blades together”. This movement commonly occurs during a rowing movement and should occur in the catch phase of swimming.
Protraction (abduction) Scapula
Protraction is the opposite of scapular retraction. The scapula is moved anteriorly and laterally along the back, moving the arm and shoulder joint anteriorly. If both shoulder blades are protracted, the scapulae are separated and the pectoralis major muscles (in the front of the chest) are squeezed together. Protraction occurs if an athlete reaches forward during the entry phase of freestyle
The shoulder blades are raised in a shrugging motion. The scapula are elevated when a swimmer’s arm enters the water during freestyle.
The scapula is lowered from elevation to a depressed position. The scapulae may be depressed so that the angle formed by the neck and shoulders is obtuse, giving the appearance of “slumped” shoulders. This is most noted in swimmers with poor posture outside the pool. Rarely are the shoulders depressed during swimming.
Up Rotation Scapula
Moving the scapulae to rotate the glenoid upward. Whenever the arm moves overhead the shoulder blade upwardly rotates to provide safe movement, avoiding impingement of the rotator cuff muscles. This movement is specifically controlled by the: serratus anterior, lower trapezius, upper trapezius (more on them later).
Down Rotation Scapula
The opposite of upward rotation, downward rotation occurs as the arm returns from being overhead. The scapula moves so the glenoid faces downward.
Posterior Tilt Scapula
The scapula moves toward the back of the body, orienting the glenoid posteriorly. This occurs during overhead movement, specifically flexion.
Anterior Tilt Scapula
The opposite of posterior tilt, as the scapula moves towards the front of the body the glenoid is oriented anteriorly. This occurs when the arm is lowered from overhead movements.
Abduction Glenohumeral joint
Arm abduction occurs when the arms are held at the sides, parallel to the length of the torso, and then raised in the frontal plane. This movement may be broken down into two parts: true abduction of the arm, which takes the humerus from parallel to the spine to perpendicular; and upward rotation of the scapula, which raises the humerus above the shoulders until it points upwards. This motion occurs in the frontal plane during the outsweep of breaststroke or during a wide freestyle catch.
Adduction Glenohumeral joint
Arm adduction is the opposite of arm abduction. It can be broken down into two parts: downward rotation of the scapula and true adduction of the arm. This motion occurs in the frontal plane when a swimmer incorrectly crosses their arm across their body during the freestyle catch
Flexion Glenohumeral joint
The humerus is rotated out of the plane of the torso so that it points forward (anteriorly). This motion occurs in the sagittal plane during the recovery of backstroke or when the arms shoot forward off the block.
Extension Glenohumeral joint
The humerus is rotated out of the plane of the torso so that it points backwards (posteriorly). This motion is the opposite of flexion, but still occurs in the sagittal plane. The glenohumeral joint undergoes extension while the athlete pulls during freestyle.
Internal rotation of the Glenohumeral joint
Internal rotation of the arm is most easily observed when the elbow and shoulder are held at a 90-degree angle of flexion. Internal rotation occurs when the arm is rotated at the shoulder so that the fingers change from pointing straight forward to pointing towards (perpendicular) the ground. This motion occurs during the catch phase of freestyle while the swimmer achieves an early vertical catch.
External rotation of the Glenohumeral joint
External rotation of the glenohumeral joint is the opposite of internal rotation of the arm. External rotation occurs when the arm is rotated at the shoulder so that the fingers change from pointing straight forward to pointing towards (perpendicular) the ceiling. This motion is rarely utilized in swimming, and can leading to muscular imbalances between the internal and external rotator muscles.
First class lever: when two forces are applied on either side of an axis and the fulcrum lies between the effort and the load. For example, a seesaw or the triceps at elbow joint.
Second class lever: when the load is applied between the fulcrum and the point where the effort is exerted. Less resistance is necessary to move a load. Like carying wheelbarrow or isolated contraction of the bracioradialis.
Third class lever: when the load is located at the end of the lever and the effort lies between the fulcrum and the load. This is like a drawbridge or flexion at the elbow. Most movable joints in the body.
Terms and descriptions taken from the Swimmer's Shoulder System available for purchase.