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

Abstract

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. 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. 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. 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.