1. Lee E. Brown, EdD, CSCS,*D California State University, Fullerton THE EFFECT OF SHORT TERM ISOKINETIC TRAINING ON LIMB VELOCITY

2. PrefacePreface Acute performance gains are attributed to learning. Motor learning is a neural event demonstrated physically. Neural adaptation has been shown relative to force. Activation or rate coding are responsible.

3. IntroductionIntroduction Force is only a byproduct of acceleration. Acceleration is the key to velocity. Maximum velocity results in maximum energy or force. KEY is to maximize the rate of force development.

4. Sport Physics Mass = quantity of matter a body contains. Weight = mass x accel. of gravity. Velocity = rate of change in position. Acceleration = rate of change in velocity. Force = mass x acceleration. Torque = force x lever arm. Work = torque x distance. Power = work/time.

5. ImplementsImplements

6. ObjectsObjects

7. LaunchingLaunching

8. MediumMedium

9. InertiaInertia

10. EnergyEnergy Kinetic Energy = ½ mass x v 2 300 grain bullet (M = (300 gr)/[7000 gr/lb 32.2 ft/sec 2 ] = 0.00133 lb sec 2 /ft ) v of 10f/s (.5x0.00133x10 2 ) = 0.06ft/lbs v of 3000f/s (.5x0.00133x3000 2 )=5958ft/lbs

12. MeasurementMeasurement Resultant implement velocity is derived from human movement. Human movement is a function of neural and morphologic changes. Measurement of velocity is fundamental to performance. Isokinetics allows a window into human movement speed variability.

13. (RVD) (LR) (DCC)

14. VariablesVariables RVD is sensitive to speed and human variability. LR is a function of ACCROM. Force is sensitive to speed and human variability. DCC is machine controlled.

15. Brown, L. E., Whitehurst, M., Gilbert, P.R. & Buchalter, D.N. (1995). The effect of velocity and gender on load range during knee extension and flexion exercise on an isokinetic device. J. Orthop. Sports Phys. Ther., 21(2), 107-112. * * * * *

16. Moritani, T. & deVries, H.A. (1979). Neural factors versus hypertrophy in the time course of muscle strength gain. American Journal of Physical Medicine, 58(3), 115-30. Strength gains of untrained after initial 8- weeks are due to neural adaptation then muscular hypertrophy.

17. Prevost, M.C., Nelson, A.G., & Maraj, B.K.V. (1999). The effect of two days of velocity-specific isokinetic training on torque production. Journal of Strength and Conditioning Research, 13(1), 35-39. Strength gains following short-term training utilizing isokinetic dynamometry are velocity specific (fast only) and related to neural adaptation. (~25% improvement) *

18. RationaleRationale Force is only a function of velocity. Max velocity is a function of acceleration. Therefore, training specificity should be reflected in acceleration and any force increase should be reflected in a concomitant increase in acceleration.

19. HypothesesHypotheses The fast training group will decrease RVD at the fast speed only. The slow group will exhibit no RVD change at any speed. The slow group will increase force at the slow speed only. The control group will exhibit no change at any speed.

20. Testing and Training Design 60 college age male and female subjects. Three random groups (control, fast and slow). Five maximal repetitions at 60 and 240 d/s. Test on day one and day seven. Two training sessions separated by 48 hours consisting of 3 sets of 8 repetitions at 60 or 240 d/s.

22. Diverted the signal to an A/D board sampling at 1000Hz. Raw ASCII data exported to Excel as time, force, velocity and position columns. Three univariate (RVD, LR, & Force ) four-way mixed factorial (2 speeds X 2 times X 2 genders X 3 groups ) ANOVA’s to analyze the data. Data Collection and Analysis

23. CVrICCSEM % Error RVD13.15.27.40.119.64 LR.49.40.58*.23.30 DCCROM16.37.42.59.1011.23 Force22.18.89*.94*6.455.42 Reliability at 60 d/s

24. CVrICCSEM % Error RVD9.00.77*.87*.433.19 LR3.43.71*.83*.571.40 DCCROM1.60.37*.55*.231.05 Force29.72.95*.97*3.995.13 Reliability at 240 d/s

25. Significantly high variable reliability at fast speeds but not slow. ResultsResults

26. First study to evaluate velocity reliability. Reliability of force consistent with: –Farrell, 1986 –Brown, 1992 & 1993 Mean values consistent with: –Farrell, 1986 –Taylor, 1991 –Brown, 1992 & 1993 –Wilson, 1997 –Greenblatt, 1997 ReliabilityReliability

27. DCCROM at 60 d/s

28. DCCROM at 240 d/s

29. Force at 60 d/s

30. Force at 240 d/s

31. No significant differences in force or DCCROM by time for any group. ResultsResults

32. Force inconsistent with Prevost, 1999. Probably due to data reduction techniques. DCCROM consistent with: –Farrell, 1986 –Taylor, 1991 –Brown, 1995 Force and Deceleration

33. RVD at 60 d/s

34. LR at 60 d/s

35. RVD at 240 d/s

36. LR at 240 d/s

37. Significant decrease in RVD by time for the slow group at the slow speed and for the fast group at the fast speed. Significant increase in LR by time for the slow group at the slow speed and for the fast group at the fast speed. ResultsResults

38. Reduction in RVD results in LR increase. Reduction of RVD with maintenance of force results in an increase in rate of force development. Acceleration and Load Range

39. ConclusionsConclusions Acute improvements may be explained as the result of neural adaptations. Increased motor unit recruitment or firing rate. Increased rate of force development may maximize human performance. Future research should determine optimum frequency and volume for velocity specific training.

40. Next Class RVD, RFD F mm lab Chapter 6 Abstract homework