Variable Resistance – Implication for Swimming Training

1. Variable Resistance – Implication for Swimming Training Type of Muscle Contraction Static Dynamic Angle of Pull – Invention of Isokinetic machine Swimming – Training for optimum muscle power and strength improvement By Jackson Pui Man Wai, Ph.D.

3. First-Class lever 第一型槓桿

4. Second-Class lever 第二型槓桿

5. Third-Class lever 第三型槓桿

6. 40 kg x 1 m = 40 kgm 20 kg x 2 m = 40 kgm (20+5) kg x 1.6 m = 40 kgm

7. Muscle Angle of Pull - Tension Relationship Source: Fox, Bower, and Foss. The Physiological Basis of Physical Education and Athletics.

8. Muscle Angle of Pull - Tension Relationship Source: Fox, Bower, and Foss. The Physiological Basis of Physical Education and Athletics.

9. LW LF LF LF LW LW Effect of Angle of Pull on Muscle tension Experimental setting

10. LF LF LF LW LW LW Effect of Angle of Pull on Muscle tension Realistic setting

11. Open System F = ma  a = F/m  a  F, Thus  F  a Energy of muscle force converts to energy of acceleration

12. Closed system Energy cannot be dissipated by acceleration, energy of acceleration is absorbed as energy of resistance. • F = ma = mR (constant V) • R  Fthus  F  R

13. Isokinetic Knee Extension and Flexion ~117° Torque curves of quadriceps and hamstring muscle groups of normal subjects performed at 22.5°·s-1 ~147°

22. CYBEX II Isokinetic Device Shoulder Adduction and Abduction

24. THE END