Variation between fast and slow twitch muscle fibres during concentric and eccentric movements

1
Variation between fast and slow twitch muscle
fibres during concentric and eccentric movements

• Jos Peeters / Patrick Esser
• Faculty of Kinesiology
• University of Calgary

2
Overview

• Introduction
• Method
• Experimental results and discussion
• Conclusion
• Future work

3

• Concentric action
• Muscles apply enough force to overcome the
  resistance so that it shortens as it acts
• Eccentric action
• The resistance is greater than the force
  applied by the muscle so that the muscle
  lengthens as it acts.

4
Suggestion 1 (Walter)

• Concentric Motor Unit MU
• Small MU ? Slow
• Big MU ? Fast
• Biggest MU ? Fastest
• (Henneman 1968)

Non controlled EMG

• Eccentric is reversal to concentric
• Big MU ? Fast
• Small MU ? Slow

5
Suggestion 2 (Vincent)

• Concentric is equal to Eccentric
• Small MU ? Slow ? Low frequency
• Big MU ? Fast ? High frequency

• No shift to right in frequency spectrum

• We assume that slow twitch muscle fibres
  produce low frequency signals

6
Purpose

• To see if there is a frequency shift to the
  higher frequencies in the eccentric action of the
  quadriceps femoris

7
Overview

• Introduction
• Method
• Experimental results and discussion
• Conclusion
• Future work

8
Quadriceps femoris
9
Muscle fibers

• Fast twitch (Type 1)
• Vastus lateralis 42.3
• Rectus femoris 35.4
• Vastus medialis 52.1

• Slow twitch (Type 2)
• Vastus lateralis 57.7
• Rectus femoris 64.6
• Vastus medialis 47.9

(Colling 1997)
10
Setup

• 3 Subjects (men)
• Biodex
• EMG System
• Isometric
• Isokinetic (eccentric and concentric)
• LabView 7.1 (feedback and analyses)

11

• Maximal voluntary contraction (MVC)
• Feedback on 20 of MVC
• Feedback on 20 of EMG (RMS)

12
Protocol
13
Excluding factors

• Fatigue (Pincivero et al. 2001)
• Length of muscle (ArendtNielsen et al. 1992)
• Movement EMG electrodes

14
Analysing with LabView

• Von Tscharner 2000

15
Analysing with LabView

• Decompose EMG signal, 1024 points
• Multiply by overlapping

• Normalize (integral)

16
Overview

• Introduction
• Method
• Experimental results and discussion
• Conclusion
• Future work

17
Results

• Example Single trial
• Red ? Concentric
• White ? Eccentric

18
20 of MVC
VL
RF
VM
19
20 of EMG
VL
RF
VM
20
Discussion

• Subject selects recruitment pattern
• Force does not select pattern
• Purpose of force does select pattern
• (von Tscharner et al. 2003)

• 100 MVC should recruit all Fibres
• 20 MVC should recruit mainly slow twitch

21
Results 2
White 100 MVC at 70 deg Red 20 MVC at 70 deg
VL
RF
VM
22
Overview

• Introduction
• Method
• Experimental results and discussion
• Conclusion
• Future work

23
Conclusion

• No shift in recruitment pattern
• Concentric is equal to Eccentric

• Suggestion 2 seems to be correct

• There is no change in recruitment

OR

• There is a change but sEMG frequency cannot
  detect it

24
Conclusion

• Final Conclusion
• sEMG seems not to be sensitive enough for
  detecting differences or shifts in recruitment
  patterns

25
Overview

• Introduction
• Method
• Experimental results and discussion
• Conclusion
• Future work

26
Future work

• Give feedback on other muscle
• More subjects
• Statistics
• Shifting wavelets for higher resolution in
  analysed data (more frequencies)

27
Acknowledgements

• Walter Herzog
• Vincent von Tscharner
• Ali Oskouei
• Andrzej Stano
• Patria Hume