M. Tech. Chiro. / The purpose of this study was to determine the effect that C5 and C6 spinal manipulative therapy had on alpha motorneuron excitability of the musculocutaneous nerve in the biceps brachii muscle. Readings were recorded using Electromyography (EMG). Eighty asymptomatic subjects participated in this study. The subjects selected had to be between 18 and 35 years of age, having experienced no cervical pain, discomfort or pathology. The subjects had to present with a C5 or C6 joint motion restriction based on motion and static palpation. Patients were selected based on their response to advertisements posted throughout the Technikon Witwatersrand. Forty of the subjects were placed in the test group and received C5 or C6 joint manipulation once off. The other forty subjects were placed in the control group. EMG readings were taken before, at the time of, and after the spinal manipulative therapy, to ascertain whether the adjustment influenced the strength of the biceps brachii contraction and the reflexive action of the muscle. Pressure algometry was used on the biceps brachii as a subjective test on each patient. A repeated measure student’s t-test was performed, including a Normality and Equal Variance Test for control and trial groups. This study showed that spinal manipulative therapy momentarily increases alpha motorneuron excitability in the biceps brachii muscle in 71.4% of the patients with C5-C6 joint motion restrictions. / Dr. C. Yelverton Dr. C. J. Hay