Kinesiology of An Athletic Movement: Left Hand Hockey Slap Shot

1. Kinesiology of An Athletic Movement: Left Hand Hockey Slap Shot Kaitlin Notarfrancesco Jennifer O’Brien Samantha Cipollo Brian Sutherland Stan Grinberg

2. Introduction: • A slap shot in ice hockey is the hardest shot. It has 6 stages which are executed in one fluid motion.  • Preparation • The windup • The downswing • Loading the stick • Impact • The follow-through (D., 1996)

3. Description of Each Stage The Windup:The player draws his stick back by raising his posterior arm (the one furthest from the target) and rotates both his trunk and hips to raise the blade of his stick as far behind and above him as possible. The more the trunk, hip and shoulder muscles are stretched, the greater the force generated when they are contracted. The further the stick is drawn back, the greater the velocity of the shot -- giving players with longer arms and sticks an advantage. The weight transfer is from the front foot (closest to the target) to the back foot (from the smallest muscles to the biggest muscles). (D., 1996) Preliminary Movement:The feet, hips and shoulders are aligned to be perpendicular to the target and the stick is positioned at a comfortable distance from the torso.

4. …Continued

5. …Continued • The Downswing:The shooter rotates his hips, trunk and shoulders, causing the stick to accelerate forward and downward until the blade comes in contact with the ice approximately four inches (10 centimeters) behind the puck.   (2006) (D., 1996)

6. …Continued • Loading the stick :At this point, the shooter continues to apply pressure on the stick by pushing the lower hand against the shaft and holding the upper end of the stick close to the body. This causes the shaft to bow and thereby store energy   (D., 1996)

7. …Continued • Impact:As the movement continues, the blade catches the puck, releases energy and accelerates the puck as it clears the ice. Ideally, the puck is struck by the heel of the blade, which is the "sweet spot" of a hockey stick: because it is closer to and in line with the shaft it offers more effective energy transfer. The further out on the blade, the more torque, or twisting force, there is . (D., 1996)

8. …Continued • The Follow-Through:The force in the body is released towards the target and all the weight is on the front foot. (D., 1996)

9. Slap Shot

10. Muscles Involved: • Shoulder Adduction: Pectoralis Major Latissiumus Dorsi Teres Major • Shoulder Flexion: Anterior Deltoid • Shoulder Internal Rotation: Pectoralis Major Subscapularis (Neumann, 2002)

11. …Continued Trunk Rotation: Internal/External Obliques Multifidus Hip Flexion: Psoas Iliacus Pectineus Elbow Extension: Tripceps Brachii Forearm Pronation: Quadratus Wrist Flexion: Flexor Carpi Radiallis and Ulnaris (Neumann, 2002)

12. Types of Muscle Contractions: Trunk Rotation: Eccentric Stabilizers -Internal/External Obliques -Rectus/Transverse Abdominis “The trunk muscles (abdominal, hip and low back muscles) combine to make up the "core" of the body. When the abdominal muscles contract, they act as a sheet of armor to protect internal organs of the body.  The stronger the abdominal muscles the greater the chance that they will not be overloaded or strained from a quick, powerful twisting movement, as when shooting the puck” (Kubachka MS, CSCS, ) (Neumann, 2002)

13. Agonist, Antagonist, Synergist, Stabilizer, and Neutralizer • Agonist: Left external oblique and Right internal oblique • Antagonist: Right external oblique and Left internal oblique • Synergist: Transverse and Rectus Abdominis • Stablizer: Muscles of the lower extremities • Neutralizers: Deep back muscles (Neumann, 2002)

14. Trunk Rotation • Internal and External Obliques,Multifidus • Strong rotation potential due to large cross-section area and favorable leverage system. • External oblique functions synergistically with the contralateral internal oblique muscle producing a diagonal line of force. By considering each muscle separately the external oblique is a contralateral rotator of the trunk and the internal oblique is an ipsilateral rotator of the trunk. • The multifidi muscle provides extension stability to the lumbar region during axial rotation. • Torque demands are relatively large during high power axial rotations, such as the slap shot, but very low during slow twist, such as walking. Because axial rotation occurs in the horizontal plane, the muscles do not have to overcome the external torque generated by gravity. Their primary resistance is that caused by the inertia of the upper body and the passive tension created by the stretching antagonist muscles. (Neumann, 2002)

15. Trunk Rotation Continued Muscle Motion (Neumann, 2002)

16. Trunk Rotation Continued • The axis of rotation is with in the amphiarthrosis joint of T6 a class 1 lever system • Relatively light weight hockey stick and one arm close to the body keeps the center of mass close to normal • The Radius of Gyration - distance from the AOR to the COM being relatively short – the mass moment of inertia remains low allowing for a greater force and twist to the truck by the active length tension of the muscles which, during the concentric contraction, are the main internal forces. (Neumann, 2002)

17. Thoracolumbar axial rotation • 35 degree Arc • 30 degrees of thoracic rotation • 5 degrees of lumbar rotation (Neumann, 2002)

18. Acceleration • Hockey is a high-velocity anaerobic sprint sport, including acceleration, deceleration, abrupt stops, and explosive starts. • As a full-collision sport, hockey requires large muscle mass and exceptional strength, but it also demands high relative strength for efficient movement. Extraordinary visual skills and the ability to execute fine motor skills under fatigue and duress are critical components. • hand-eye coordination, reaction abilities, core power, balanced flexibility, proprioception, unilateral balance, coordination, and agility all contribute to success. • Speed is important but quickness and speed endurance are even more crucial. (CRAM Science, 2007)

19. The key to a good slapshot is the conversion of angular momentum to linear momentum... • Linear momentum is the product of mass and velocity, so, the more linear momentum that a puck has, the faster it is moving in a direction along a line (towards the back of the net if you’re lucky). • The mass of the puck refers to how much inertia, or resistance to change in motion it has. • The law of inertia is Newton’s first law. • It states that an object at rest remains at rest and an object in motion remains in motion with a constant velocity unless it experiences a net external force • To give a puck linear momentum, a hockey player strikes the puck with a stick that isn’t moving along a line, but that is rotating. This is where angular momentum comes in. (CRAM Science, 2007)

20. …Continued • Angular momentum is the product of the moment of inertia and angular velocity. • The angular velocity is how fast the motion of the stick sweeps out an angle in a certain direction. • The moment of inertia is to angular motion what mass is to linear motion, and it depends on the distribution of mass about a pivot point. The further the mass is away from the pivot, the higher the moment of inertia will be. By transferring their weight from their back foot to their front, and by rotating their torso, a hockey player generates a significant amount of angular momentum while shooting a slap shot. (CRAM Science, 2007)

21. References: • Kubachka MS, CSCS, Ed Training For Better Hockey . Retrieved April 27, 2007, from Training The Midsection For Hockey Web site: http://www.optimumpt.com/005.htm • Neumann, Donald A. (2002). Kinesiology of the Musculoskeletal System. Missouri, St Louis: Mosby, Inc. • (April 2006). Skills. Retrieved April 27, 2007, from The Hockey Source Web site: http://www.thehockeysource.tv/sectionsourceknowledge/skills.php#_Biomechanics_of_Skills • D., Chris (1996). How Hockey Works. Retrieved May 7, 2007, from The Six Stages of the Slapshot Web site: http://www.geocities.com/Colosseum/5296/slapshot.html • CRAM Science, (2007 ). CRAM Science. Retrieved May 2, 2007, from Sportology Web site: http://www.cramscience.ca/es.php?a=143