The effect of sacroiliac joint manipulation on gluteus maximus muscle activity in asymptomatic participants

Abstract

Purpose: The effects of spinal manipulation are well documented; however there is a gap in the current literature regarding the exact mechanisms underlying the effectiveness of spinal manipulation. Further evidence is required to improve the understanding of the neurophysiological effects of spinal manipulative therapy and its effect on muscle activity. The objectives of this study were to investigate the effects of sacroiliac joint manipulation on gluteus maximus muscle activity in an asymptomatic sample group when compared to a placebo group Methods: A randomized, controlled, pre-test, post-test repeated measures design allowed for 28 participants, aged 18-40 years old, with sacroiliac joint dysfunction to be allocated into either a sacroiliac joint manipulation or a placebo group. Muscle activity of the gluteus maximus was measured before intervention and again 10 minutes post intervention. IBM SPSS was used to analyse the data with significance set at (p=0.05). Repeated measures ANOVA testing was used to determine the significance within and between groups. Results: There was evidence of an improvement in the intervention compared with the placebo group from pre to post for outcomes of Channel A mean and maximum values, and for Channel B maximum values. In the other measures there was a trend observed but insufficient evidence to conclude that it was a real effect. The partial eta squared values were relatively small for these non-significant effects and medium to large for the significant effects. Conclusion: Analysis of the results revealed that there was evidence of an improvement in the intervention group when compared with the placebo group in some of the outcomes measured while other outcomes measured trended towards an improvement but lacked a sufficiently large sample size to conclude that it was a statistically significant effect.