1. EDU4SBM Sports Biomechanics 1 Lecture Week 7 Balance and Stability, Core Stability, COG

2. EDU4SBM Sports Biomechanics 2 Balance and Stability “How balanced are you?” Skilled athletes are able to employ certain tactics to increase their stability under oncoming forces, practically bracing themselves to be immovable. Chris Judd and Jimmy Bartel Young athletes learning a skill:

3. EDU4SBM Sports Biomechanics 3 Some sports depend almost exclusively on As soon as the athlete loses balance, he or she loses the contest. The following sports fall into that category: Cycling Speed skating Judo Figure skating Diving Weightlifting Skiing Gymnastics Fencing Wrestling

4. EDU4SBM Sports Biomechanics 4 Other sports require athletes to These sports have similar movement patterns and include the following: Baseball and softball Ice hockey Football Tennis Basketball Field hockey Soccer Volleyball

5. EDU4SBM Sports Biomechanics 5 Types of stability 1.Linear Stability is the resistance of an athlete or object against being moved in a certain direction Sport dependent Football Baseball Catcher 2.Rotary Stability is the resistance of an athlete or object against being tilted, tipped over, up ended or spun around in a circle.

6. EDU4SBM Sports Biomechanics 6 Centre of Gravity

7. EDU4SBM Sports Biomechanics 7 Factors which affect balance and stability  The size of the base of support  The position of the line of the COG relative to the base of support  The height of the COG  The mass of the body

8. EDU4SBM Sports Biomechanics 8 The Size of the Base of support A person is more stable when standing on two feet than does a person standing on one

9. EDU4SBM Sports Biomechanics 9

10. 10 The position of the line of the COG relative to the base of support The closer the line of the COG is to being directly over the base of support -> The closer the line of the COG is to being at the edge of the base of support -> This is required by many sports: ie: diving, sprint start

11. EDU4SBM Sports Biomechanics 11 The position of the line of the COG relative to the base of support

12. EDU4SBM Sports Biomechanics 12 The height of the COG

13. EDU4SBM Sports Biomechanics 13 The mass of the body

14. EDU4SBM Sports Biomechanics 14 Centre of Gravity, Stability & Balance Stability and balance will be easier if: The mass is large The base is large The centre of gravity is low The centre of gravity is located over the base Headstand Handstand

15. EDU4SBM Sports Biomechanics 15 The nature of the crouch position reflects three important principles of stability: 1)A broader base of support increases stability. (A catcher’s stance places feet more than hip-width apart.) 2)Centralizing the line of gravity inside the support base increases stability. (A straight back and head held upright centralize the line of gravity.) 3)A lower center of gravity increases stability. (Crouching’s deep knee bend lowers the center of gravity.)

16. EDU4SBM Sports Biomechanics 16 Many times, stability depends on an athlete’s ability to put the line of gravity towards an oncoming force. The movement temporarily unbalances the athlete, but then the impact of the force re- balances him or her.

17. EDU4SBM Sports Biomechanics 17 CORE STABILITY http://www.brianmac.co.uk/corestab.htm Most throwing and striking sports require an efficient transfer of force from the ground up to achieve maximum acceleration of the upper limb or implement. This transfer of force is often a function of how well the upper body and lower body are connected. By strengthening the trunk, the athlete creates a solid unit capable of developing and transferring forces from the legs through the trunk to the arms and possibly the implement. The sum of these integrated forces results in optimal acceleration of the ball or implement. Major sports in which this transfer of forces is critical for good performance include the following: Baseball, Softball, Discus, Shot Put, Football, Tennis, Golf, Basketball, Javelin