Testing the kinetic chain (the tests)

Todays post is about the tests you can use to assess swimmers' physical strengths and weaknesses aling with the health of their kinetic chain. These test are: (1) the core stability test, (2) the shoulder flexibility test, (3) the scapula stabilization test, (4) the rotator cuff strength test, and (5) the vertical jump test.

Core stability test

Core stability is critical for swimming performance. Insufficient strength in the core musculature, or the inability to control the force that's produced by those muscles can lead to injury and inefficiency when swimming. The core stability test assesses the strength and control you have over those muscles. To get the best estimate of your core stability, you will need a blood pressure cuff and someone to assist with this exercise.

1. Lie on your back, maintaining the normal curvature of your spine.
2. Place the blood pressure cuff under the small of your back and bend the hips and knees 90 degrees.
3. ''Lock down'' the pelvis by contracting your abdominal and lower-back muscles. The goal is to contract these muscles so the pelvis does not moving during the exercise.
4. In this position, your partner should inflate the blood pressure cuff to read a pressure of 40mmHg.
5. Alternate straightening and lowering the right and left legs toward the floor and returning to the starting position.
6. Focus on maintaining a constant pressure of 40mmHg in blood pressure cuff throughout the exercise.
7. Repeat until you have performed 10 repetitions with each leg.

In performing this test, many athletes can do one of three things. They attempt to stabilize the pelvis in these ways:

• Pushing the lower back into the ground (flattening out the back), which causes the pressure in the blood pressure cuff to rise
• Arching the back, which causes the pressure in the cuff to drop
• Adequately stabilizing the pelvis using the abdominal and lower-back muscles for the entire 10 repetitions

Ideally, swimmers should be able to achieve the third scenario, but unfortunately, most athletes fall into one of the first two categories.

Shoulder flexibility test

Swimmers commonly exhibit a reduced range of motion in the shoulder, particularly in internal rotation. Internal rotation is a big component of virtually every stroke. Though this repetitive motion, the muscles can become quite strong but also develop tightness. Any decreased range of motion can cause the ball-and-socket joint in the shoulder to move abnormally or place undue stress on the structures in the shoulder, either of which could predispose you to injury.

To asses any defficiences, a health care practinioner should periodically measure range of motion in the shoulders.

1. Lying on a treatment table, raise the right arm 90 degrees to the side and flex the elbow 90 degrees as well. Your fingers should point toward the ceiling in the starting position.
2. Without moving the upper arm, rotate the shoulder backward into external rotation as far as you can. Hold this position while the examiner measures the amount of external rotation using a goniometer.
3. Rotate the shoulder forward into internal rotation as far as you can. Hold this position while the examiner measures the amount of internal rotation.
4. The examiner should push lightly on the front of the shoulder throughout the test to stabilize the shoulder blade and minimize movement.
5. Compute the total range of motion (the amount of internal rotation plus the amount of external rotation).
6. Perform the test on the other shoulder as well.

Scapular stabilization test

This test evaluates the strength of the muscles that control the shoulder blades. When these muscles are weak, greater stress is placed on the muscles of the rotator cuff, and the chance of impingement increases. This test is fairly simple to perform, but it does require the assistance of a coach.

1. With your hands at your sides, hold a 0.5 to 1 kg weigth in each hand.
2. Slowly lift the weights until they are above the head, and then slowly lower the weights back to the starting position. The arms should move in what is called the plane of the scapula, not straigth out to the side, but approximately 30 degrees forward of that position.
3. The tester should watch how the shoulder blades move during this test.
4. Perform 10 reps of this exercise to induce some fatigue in the muscles.

Normally, the shoulder blades will stay flush with the torso and rotate upward and downward in a smooth motion as the arms are raised and lowered. When there is a weakness in the scapula stabilizers, the shoulder blades will pop off the torso at some point during the movement, especially when the arms are lowered.

Rotator cuff strength test

The four muscles of the rotator cuff (teres minor, infraspinatus, subcsapularis, and supraspinatus) are responsible for generating force and stabilizing the shoulder in all of the swimming strokes. The internal rotators tend to become stronger than the external rotators in swimmers, setting up a force imbalance in the shoulder. The rotator cuff strength test examines the strength in the external rotators to determine if additional strengthening of these muscles are needed. This test is best performed by a qualified health care practioner.

1. In a seated position, raise your left arm out to the side 90 degrees and flex the elbow 90 degrees as well. Your hand should point to the ceiling.
2. The examiner should gently stabilize your elbow with one hand while trying to internally rotate your shoulder by pushing on your wrist.
3. Try to maintain the initial 90-90 position; do not let the examiner rotate your shoulder.
4. Based on your strength, the examiner will score you on a scale of 0 to 5. Most swimmers will be rated a 3,4, or 5. 

Anything less than 5 indicates you need to strengthen the external rotators.

Vertical jump test

The vertical jump is a test of lower-body power, a combination of force and speed. Explosive lower-body power will allow you to drive of the starting blocks or off the wall after every turn. Leg strength also is the foundation of a strong kick. You can measure vertical jump without using any special equipment.

1. Stand facing a wall and reach with both hands while keeping both feet flat on the ground. Have a partner mark the tips of your fingers using chalk. This establishes your reach height.
2. Put some chalk on the fingers of your right hand and turn sideways to the wall.
3. Jump as high as you can without taking any approach steps. Touch the wall with your hand at the peak of your jump, leaving a chalk mark.
4. Perform at least two jumps; continue until you are not able to jump any higher.
5. Measure the height of the highest mark on the wall for your jump heigth.
6. To calculate your vertical jump, subtract your reach height from the jump height.