3.1. Dynamometer
The force data were not normally distributed and, therefore, a
logarithm transformation was performed. No sign of heteroscedasticity
was found in the log-transformed data which were visually
inspected by plotting the difference and mean from test and retest.
Furthermore, there was no statistically significant difference
between test and retest except from the abduction test. The results
showed that the dynamometer is reliable with LOA% presenting
low values ranging from 3.2–7.6% and ICC ranging from 0.89–
0.98 (Table 2, Fig. 3). The visual inspection of the Bland–Altman
plots (Fig. 3) showed that all the mean differences were close to
zero and that the difference between test and retest remained
similar across the scale.
3.2. Surface electromyography
The EMG data were normally distributed for the difference
between test and retest. Further, no sign of heteroscedasticity
was found.
The result from MVC showed an absolute reliability of LOA%
ranging from 39.4–67.1% while the relative reliability showed
acceptable reliability with ICC = 0.79–0.86 (Table 2, Fig. 3).
The results from the isometric submaximal contractions were
calculated as both absolute and normalized RMS values. The absolute
reliability described by LOA was similar for absolute
(LOA = 20.0–68.4%) and normalized (LOA = 42.4–66.5%) RMS
values (Table 3, Figs. 4 and 5). However, the results concerning
the relative reliability showed higher ICC for absolute
(ICC = 0.82–0.92) compared with normalized (ICC = 0.57–0.72)
RMS values (Table 3, Figs. 4 and 5).