Lee E. Brown, EdD, CSCS,*D

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THE EFFECT OF SHORT TERM ISOKINETIC TRAINING ON
LIMB VELOCITY

• Lee E. Brown, EdD, CSCS,D
• California State University, Fullerton

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Preface

• 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.

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Introduction

• 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.

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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.

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Implements
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Objects
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Launching
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Medium
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Inertia
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Energy

• Kinetic Energy ½ mass x v2

• 300 grain bullet (M (300 gr)/7000 gr/lb 32.2
  ft/sec2 0.00133 lb sec2/ft )
• v of 10f/s (.5x0.00133x102) 0.06ft/lbs
• v of 3000f/s (.5x0.00133x30002)5958ft/lbs

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Measurement

• 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.

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(DCC)
(RVD)
(LR)
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Variables

• 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.

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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.
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Strength gains of untrained after initial 8-weeks
are due to neural adaptation then muscular
hypertrophy.

• 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.

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Strength gains following short-term training
utilizing isokinetic dynamometry are velocity
specific (fast only) and related to neural
adaptation. (25 improvement)

• 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.

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Rationale

• 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.

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Hypotheses

• 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.

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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.

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Data Collection and Analysis

• 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 ) ANOVAs to analyze the data.

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Reliability at 60 d/s
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Reliability at 240 d/s
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Results

• Significantly high variable reliability at fast
  speeds but not slow.

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Reliability

• 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

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DCCROM at 60 d/s
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DCCROM at 240 d/s
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Force at 60 d/s
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Force at 240 d/s
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Results

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

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Force and Deceleration

• Force inconsistent with Prevost, 1999.
• Probably due to data reduction techniques.
• DCCROM consistent with
• Farrell, 1986
• Taylor, 1991
• Brown, 1995

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RVD at 60 d/s
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LR at 60 d/s
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RVD at 240 d/s
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LR at 240 d/s
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Results

• 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.

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Acceleration and Load Range

• Reduction in RVD results in LR increase.
• Reduction of RVD with maintenance of force
  results in an increase in rate of force
  development.

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Conclusions

• 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.

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Next Class

• RVD, RFD Fmm lab
• Chapter 6
• Abstract homework