Abstract
M.Tech. (Chiropractic)
Aim: The aim of this study was to determine the effects of chiropractic adjustment
therapy (CAT) to the cervical spine on the reflex motorneuron excitability of C5 and C6
nerves on the biceps brachii muscle bilaterally. This study was also aimed at measuring
the subsequent increase in strength of the biceps brachii muscle.
Method: A selection of 30 participants, male or female and between the ages of 18 and
40 were recruited. Participants had to meet all the inclusion criteria and present with no
contra-indications. Only one group was used as each participant served as their own
control. Participants were seen seven times over a period of three weeks. The
measurements were taken during the 1st, 4th and 7th consultations. On the 2nd, 3rd, 5th
and 6th consultations only treatment was applied. On the 7th consultation only data was
collected and no treatment was done.
Results: Statistically significant improvement of dynamometry and electromyographic
measurements were noted over the consultation periods on both sides. No conclusion
could be made regarding the comparison of dynamometer and sEMG measurements of
the biceps brachii between each consultation and between each side (left and right)
over the study period.
Conclusion: Based on the results obtained in this research it may be deduced that
CAT may have an effect on the neurological system and further more an effect by
increasing motorneuron excitability at sites distant to the spine itself. These results are
important to the Chiropractic profession as it shows that CAT does not only produce a
segmental response, but that there are wide spread effects on structures distant to the
spinal column. The extent of the effects CAT can elicit on the nervous system requires
further investigation.