Stroke Form Analysis

Question 1

Swimming economy

Answer 1

Swimming economy is the amount of energy required to move the body a specific distance at a given velocity. It is based on the relationship of propulsive and resistive forces applied during swimming. It is influenced by factors such as swimming velocity, technical ability, gender, age and anthropometric characteristics. Swimming economy can improve with the right type of training.

Question 2

Review: Forces at Play in Swimming

Answer 2

Propulsion is the force that moves the athlete forward and drag is the force that resists movement.

Three types of resistance affect forward movement.

• Frictional drag: Occurs when water passes over a rough surface, such as a bathing suit or hair.
• Form drag: Caused by the shape of the swimmer (the less streamlined the swimmer, the greater the resistance).
• Wave drag: Occurs when the swimmer creates waves, wakes and turbulence by bouncing, by lifting the head when breathing, or by excessive or sideways kicking; also occurs when swimming in choppy water.

Question 3

The entry phase

Answer 3

The hand and arm should enter the water with a flat palm. The palm should be facing the water and the wrist should be flat and neutral. The arm and hand entry should be in line with the shoulder and aim approximately 30 degrees below the water line. Maintaining this form allows for the highest amount of propulsion and reduces drag.

Crossing the midline of the trunk and head with the extended arm is a common mistake. This movement decreases propulsion and can increase the risk of shoulder impingement.

Question 4

Entry: Common Mistakes

Answer 4

• Extreme internal rotation of the shoulder and hand during entry can increase the risk of shoulder impingement.
• Crossing the midline of the trunk and head with the extended arm decreases propulsion and increases the risk of shoulder impingement.

Question 5

Catch Phase

Answer 5

During the catch, the swimmer should flex the elbow and slightly rotate the shoulder while pointing the fingertips downward. The wrist should not bend. The elbow should remain higher than the hand. A common mistake that reduces forward propulsion is letting the fingers point forward instead of down while pushing back during the catch.

Question 6

Creating Propulsion

Answer 6

• A propulsive pull, stroke rate, muscular endurance and power all help swimmers create propulsion.
• The pull should provide as much propulsion as the swimmer is able to generate.
• Elite swimmers have a stroke rate of 70-100 strokes per minute (SPM).
• Developing muscular endurance and strength allows the swimmer to maintain muscular power for longer periods of time.
• Specific training sessions must be designed to improve biomechanics as well as to increase muscular endurance and strength.

Question 7

Summary

Answer 7

• Biomechanics of swimming is the study of forces (propulsion and drag) during the swim stroke.
• Swimming economy is the amount of energy required to move the body a specific distance at a given velocity. It is based on the relationship of propulsive and resistive forces applied during swimming.
• The four phases of the freestyle stroke are entry, catch, pull and recovery.
• Specific training sessions for muscular endurance and strength are essential for helping the swimmer maintain good technique and speed for longer periods of time.