Hypothesis
That there is a relationship between the portions of fast twitch fibres and muscle fatigue.
Methods
See sheets attached in appendix
Results
The table shows EMG fatigue gradient against conduction velocity time 1 and time 2. The result marked red was an outlier as it was much bigger then the rest of the results. So they could have been an error in the pre set of data that was obtained. This outlier made the graphical data different in terms of correlation. The outlier was not being entered into the graphical data
Figure 1 - EMG fatigue against time
The relationship between EMG against time shows a positive correlation, so has time increased EMG increased.
Figure 2 - Time versus interelectrode distance
The graph shows that further up the ulnar nerve the greater the distance the greater the time it takes. The relationship show that time it takes to travel is very quick.
Figure 3 – Conduction velocity and muscle fatigue
Shows a random set of results with no really relationship, the R values show that there is little correlation between fatigue and conduction velocity.
Discussion
Figure 1- The increase in EMG might reflect greater total muscle fiber recruitment for a fixed submaximal external force and is defined as fibers fatigue (Edwards 1981, NewhamDJ et al 1983).6. (Edwards RH, 1981, pp. 1-18.)
It is when the motor units fall to contract that muscle starts to fatigue. So because it was a fixed force and isometric contraction the muscle does not start to fatigue.
Figure 2 – The graphs shows the time and distance, when looking at the gradient of the slopes they are a bit high. In terms of the muscle contracting is nearly 100 ms-1.
Figure 3- There is no relationship of the data of fatigue and conduction velocity. When determining the maximum Voluntary Contraction errors can occur in the % accuracy of the maximum weight the subject can hold. For example if people were not putting in the effort, they could have been giving false information. So when the muscles were contracting fatigue was not effecting their contraction. Also the equipment that was used to test maximum voluntary contraction would not have been big enough to take readings of really heavy weight (high muscle contraction).
So we can reject the hypothesis in terms that there is no relation between fast twitch fibers and fatigue.
Research in to factors effecting
To increase the velocity of propagation of an action potential is to simply increase the diameter of motor axons.( Stephen Wright)
Size of larger fibers of a given class (i.e., myelinated or unmyelinated) conduct faster than smaller ones of the same class this is because larger fibers have lower longitudinal resistance than smaller ones and thus, a smaller proportion of the current leaks across the membrane. Large fibers have shorter duration refractory periods and action potential durations than small fibers. thus, maximum firing frequencies are greater in large fibers than in small myelination - with size held constant, myelinated fibers conduct faster (perhaps with the exception of very tiny fibers) .( Stephen Wright)
Subjective fatigue So far we've been dealing with objective measures of fatigue;
i.e. a decrease in the tension developed by the muscle. But this is only one
contribution to subjective fatigue---the feeling of muscle tiredness. In fact if
one records from biceps or triceps brachii while a subject is carrying a load,
one finds that the muscles are inactive. They are electrically inactive and
develop no active tension. However, the subjects rapidly feel fatigue in the
muscle; these feelings presumably originate from nociceptors or
mechanoreceptors in the muscles, ligaments or joints. But of course this is a
subjective measure of fatigue, and not related to the capacity of the muscle of develop tension. (Basmajian 4th ed. p164).
Reference
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(Basmajian.4thed.p164).http://anatomy.med.unsw.edu.au/teach/anat3141/2002/FA2_16=MUSCLE3.pdf [accessed at ]
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Edwards RH, Human muscle function and fatigue. Human muscle fatigue:physiological mechanisms. Pitman Medical, London (Ciba Foundationsymposium 82) 1981, pp. 1-18. [accessed at ]
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JP/0111 PHYSIOLOGICAL SYSTEMS/ PLP1 Measurement of Nerve Conduction Velocity in the Human Forearm. [accessed at ]
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Stephen Wright, Ph.D., 16. ACTION POTENTIAL PROPAGATION Department of Physiology [accessed at
