At the midpoint of a line running between the ischial
tuberosity and the proximal head of the fibula [32].
The digital goniometer will be positioned on the lumbar
region according to the manual instruction of the
apparatus. Surface EMG of the isometric activity of these
muscles will be recorded during holding time. Holding
time, median and mean power frequency slopes and
intercepts, as well as the slope of the standard deviation
of lumbar angle will be extracted from raw EMG using
MATLAB version 7 and analysed by SPSS, version 17.
Lumbar range of motion
Lumbar flexion and extension range of motion will be
measured according to the modified-modified Schober
(MMS) method. The MMS test has shown to produce
reliable measurements of spinal flexion and extension in
patients with LBP (Pearson’s r = 0.78 to 0.89 for flexion
and 0.69 to 0.91 for extension) compared with use of
the double inclinometer technique (Pearson’s r = 0.13 to
0.87 for flexion and 0.28 to 0.66 for extension), with less
time to obtain the measurement [33].
In this method the two posterior superior iliac spines
(PSIS) will be connected with a line on the skin and the
middle of the line (first mark) and 15 cm above (second
mark) will be marked. As the patient moves into lumbar
flexion or extension, the distance between the two
marks is measured and subtracted from the 15 cm distance
in the neutral position [33].
Data collection and analysis
An intention-to-treat analysis will be performed. In the
case of dropouts and withdrawals, the last recorded
values for the main outcome measures will be used in the
analysis. We will check if the two groups are similar for
the most important demographic characteristics and all
outcome measures at baseline. In case of finding any differences
we will adjust for them in a regression analysis.
Between-group differences in the change of scores of all
outcome measures will be analysed using the Statistical
Package for the Social Sciences (SPSS) version 17. We
will consider whether the data meet parametric or nonparametric
conditions. If parametric, ANOVA, independent
and paired t-tests will be used and in case of nonparametric
conditions we will use Kruskal-Wallis, Mann-
Whitney and Wilcoxon signed-rank tests. All analyses
will be performed blinded for treatment allocation.