Submitted in partial compliance with the requirements for the Masters’ Degree in Technology: Chiropractic, Department of Chiropractic, Durban University of Technology, Durban, South Africa, 2014. / Background: Spinal manipulation has been shown to result in neurophysiological changes, most often noted in the paraspinal muscles. These effects have been associated with an increase in paraspinal muscle contractibility; it is unclear if this leads to an increase in paraspinal muscle endurance. Objectives: To determine the effect of sacroiliac joint (SIJ) manipulation compared to a placebo treatment of the SIJ on lumbar extensor muscle endurance time. Method: A randomised, placebo-controlled pre-test post-test experimental trial, involving 40 asymptomatic male participants divided into an intervention group receiving SIJ manipulation using an impulse adjusting instrument and a placebo group receiving a pre-load force without the delivery of an impulse thrust. Outcome measures were lumbar extensor muscle endurance time, surface electromyographic (SEMG) readings, lumbar spinal range of motion, paraspinal muscle length assessment and a subjective pain measurement. Results: There was a significant difference between the groups (p=0.004) with the SIJ manipulation group showing an increase in endurance time compared to the placebo group which showed a decrease. SEMG readings increased for both groups with no statistically significant difference between the groups (p>0.05). Only extension lumbar spinal range of motion significantly improved in both groups (p=˂0.001) with no significant differences between groups (p=0.876). Only one participant reported pain during the research procedure. Conclusions: SIJ manipulation may enhance the endurance of the paraspinal muscles. This study should be conducted in a larger sample to validate the findings.

Submitted in partial compliance with the requirements for the Masters’ Degree in Technology: Chiropractic, Department of Chiropractic, Durban University of Technology, Durban, South Africa, 2014. / Background Spinal manipulative therapy (SMT) is a commonly used therapeutic modality. It has been shown that neuromuscular reflexes are elicited during spinal manipulation resulting in changes in the surrounding muscle tonicity and seen as changes in surface electromyography. Despite this little is known about the effect that SMT may have on muscle function. Increased maximum voluntary contraction (MVC) of the paraspinal muscles has been observed following lumbar SMT compared to a control and sham treatment; however its effect on muscle endurance has not been investigated. The aim of this study was to determine the effect of lumbar SMT compared to a placebo treatment on lumbar extensor muscle endurance in asymptomatic individuals. Method This study was a quantitative double blinded, pre-test and post-test placebo controlled experimental trial. Forty asymptomatic participants were randomly allocated to one of two treatment groups. One group received a single SMT applied to the L3 vertebrae and the other received the pre-load force of the SMT but no thrust. Subjective (a self-report of pain/discomfort while performing the Biering-Sorensen test) and objective [surface electromyography (sEMG), paraspinal muscle endurance time and lumbar spine range of motion] measurements were taken pre- and post-intervention. The latest version of SPSS version (IBM SPSS Inc.) was used to analyse the data. A p-value < 0.05 was considered statistically significant. Independent t-tests were used to compare means and two-way factor ANOVA (for repeated measures) was used to compare the change in the two time points between the two treatment groups (intervention and control). RESULTS There were no statistically significant differences between the intervention and placebo groups in terms of subjective reports of pain/discomfort and objective evidence of surface EMG readings, paraspinal muscle endurance time and lumbar spine range of motion.