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1. Name those factors that contribute to the propulsion of a swimmer.
2. Name those factors that impede the progress of a swimmer.
3. Explain how the propulsive and resistive factors named affect the length or frequency of the swimming stroke.
4. Complete a kinesiological analysis of a swimming stroke, identifying the anatomical and mechanical factors for success in the selected stroke, as well as those factors that limit the performance.
Mechanical Principles Mechanical Principles Applied to SwimmingApplied to Swimming
1. Swimming should produce an even progress through the water rather than cycles of speeding up and slowing down.
2. The body will move in the opposite direction from that in which the force is applied.
3. Forward motion is produced through a combination of drag force and lift force.
4. Maximum force is attained by presenting as broad a surface as possible in the propulsive movements of the limbs and by exerting a backward pressure through as great a distance as possible.
Mechanical Principles Mechanical Principles Applied to SwimmingApplied to Swimming
9. The more streamlined the body, the less the resistance to progress through the water.
10. The drag on the body in any fluid increases approximately with the square of the velocity.
11. The sudden or quick movement of a swimmer’s body, or one of its parts, at the surface of the water tends to cause whirls and eddies that create drag.
Analysis of the Sprint CrawlAnalysis of the Sprint CrawlHead and TrunkHead and Trunk
Lateral movements of the trunk will increase resistance to forward movement. Circular movements of the arms, legs or head
cause a counter movement of the rest of the body.
Turning the head to breathe must be accomplished with the least possible interference. Do not lift the head to breathe. Rotate it while tucking the chin.
Analysis of the Sprint CrawlAnalysis of the Sprint CrawlHead and TrunkHead and Trunk
After a quick inhalation, face is turned forward.
Breathe every stroke for distance events, and less often for sprints.
By alternating actions of the left and right oblique abdominals and spinal extensors, the spine and pelvis are stabilized against the pull of the shoulder and hip muscles.
Analysis of the Sprint CrawlAnalysis of the Sprint CrawlArm Stroke: Entry and SupportArm Stroke: Entry and Support
Entry should place the arm in the most advantageous position for exerting force. Forearm high and elbow pointing to the side. Hand passes in front of shoulder, reaches forward,
and is driven forward and downward into the water directly in front of the shoulder.
Elbow is slightly flexed, and extends during entry.
Analysis of the Sprint CrawlAnalysis of the Sprint CrawlArm Stroke:Catch, Pull, and PushArm Stroke:Catch, Pull, and Push Catch: propulsive action changes from
downward to backward. A quick inward movement of the hand and arm
that serves to bring the hand to a position in front of the axis of the body.
The pull phase begins with the first backward motion of the hand. Upper arm is vertical, and favors use of the large
muscles - pectoralis major and latissimus dorsi for pulling downward and backward.
Analysis of the Sprint CrawlAnalysis of the Sprint CrawlArm Stroke:Catch, Pull, and PushArm Stroke:Catch, Pull, and Push Pull: elbow should be kept high during
the first part of the pull. By bending the elbow the arm is pulled
under the body. Maximum bend occurs halfway through the
pull, when the hand begins to push water backward.
Elbow action assists in producing an S-curve, which creates propulsive lift.
Analysis of the Sprint CrawlAnalysis of the Sprint CrawlArm Stroke:Catch, Pull, and PushArm Stroke:Catch, Pull, and Push Push: transition from pull to push occurs as
the arm passes under the shoulder. As forearm passes the front of the hip, the upper
arm extends and the hands gives a quick push backward.
Release and Recovery: Pressure is relaxed, elbow & shoulder raised out of the water. Elbow swings forward and upward with hand trailing behind. Hand moves in front of shoulder ready for next entry.
Analysis of the Sprint CrawlAnalysis of the Sprint CrawlThe Kick: Nature Of MovementThe Kick: Nature Of Movement Most often used is the flutter kick. Primary role is a stabilizer and neutralizer.
Timing with arms is therefore critical.
Legs are relatively close together as they alternate in an up and down movement. Feet attain a maximum stride of 1 to 2 feet. Whiplike or lashing action for both the up and
Analysis of the Sprint CrawlAnalysis of the Sprint CrawlThe Kick: Upstroke The Kick: Upstroke Begins with thigh extension. Slight knee flexion develops near the
end of the stroke. Foot stops just below the surface.