Immediate improvements in activation amplitude levels of the deep abdominal muscle following a sacroiliac joint manipulation during rapid upper limb movement.

Objective: To assess the immediate effects on the electrical activity of the transversus abdominis/internal oblique (TrA/IO) muscle during rapid voluntary upper limb movements before and after a sacroiliac joint (SIJ) manipulation.

Methods: Twenty healthy subjects who had innominate fixation, assessed by standing flexion test, were recruited. All subjects were submitted to SIJ manipulation and the TrA/IO muscles were evaluated bilaterally, before and after the procedure, through surface electromyography while ten random rapid upper limb flexions or abductions were performed. Normality was accepted, and the paired t-test was used to determine data differences (p < 0.05). The correlations were calculated using Pearson correlation coefficient.

Results: All subjects presented an increase of SIJ mobility after manipulation (negative standing flexion test). Significant differences in muscle activation were noted to ipsi- and contralateral TrA/IO recruitment, prior to (A1) and after (A2) the manipulation. The A2 data were statistically greater than those in the A1. The Pearson coefficient revealed a strong correlation between the TrA/IO side and the increase in muscle activation amplitude level. Also, the data showed a moderate to strong correlation between this last variable and the moments of evaluation.

Conclusion: The SIJ manipulation immediately improved the electrical activity of the TrA/IO muscle during rapid voluntary upper limb movements, suggesting improved segment stability and an increment to the afferent stimuli in order to affect the motor response.