Online-Only Supplementary Material: additional details of the use of 2s moving filter
Muscle inactivity periods are independently associated with cardio-metabolic biomarkers in physically active adults
This supplemental material provides additional details of the use of 2s moving filter and presents alternative results yielded without the filter.
Due to the intermittent nature of EMG signal some dynamic activities, e.g. walking, might include brief inactivity periods. Despite being briefly inactive, energy expenditure of muscles is considerably elevated during dynamic activities. For this reason we wanted to remove inactivity periods occurring during dynamic activity by using 2s moving filter. This is illustrated in Supplemental figure.
SUPPLEMENTAL FIGURE 1. Muscle inactivity periods occurring during dynamic activities were excluded by using 2s moving filter. The figure shows EMG activities during walking analyzed with and without moving filter.
Supplemental table 1 presents muscle inactivity and activity results which were analyzed without 2s moving filter. As compared to the results analyzed without 2s moving filter, the use of filter considerably lengthened the inactivity period durations and reduced number of bursts/min. The changes in other inactivity and activity variables were only modest (Table 1 and Supplemental table 1).
SUPPLEMENTAL TABLE 1. Sex-specific muscle inactivity and activity variables analyzed without 2s moving filter.
Muscle inactivity variables Women Men Total P for sex
difference Muscle inactivity (% recording time) 66.7±11.9 71.9±11.9 68.9±12.2 .011 Sum of 5 longest inactivity periods (min) 44.1±20.9 46.4±23.2 45.1±21.9 .648 Mean of inactivity period duration (s) 2.4±1.1 2.9±1.4 2.6±1.3 .048
Muscle activity variables
Light muscle activity (%) 20.4±10.2 16.3±8.8 18.6±9.8 .009 Moderate muscle activity (%) 8.4±3.9 7.7±3.9 8.1±3.9 .301 Vigorous muscle activity (%) 4.5±5 4.1±4.4 4.3±4.8 .983 Mean amplitude (%EMGMVC) 3.3±2.2 2.5±1.7 2.9±2 .001 Mean muscle activity amplitude
(%EMGMVC) 8.7±4.5 7.6±3.6 8.2±4.2 .104
No of bursts/min 22.2±15.8 18.9±9.3 20.8±13.5 .342
Footnote: Data are means ± standard deviations. Muscle inactivity time (% of measurement time at <0.9 x EMGstanding), muscle light activity time (% at 0.9 x EMGstanding - <EMG5km/h walking), muscle moderate activity time (% at EMG5km/h walking - <2 x EMG5km/h walking), muscle vigorous activity time (% at ≥2 x EMG5km/h walking.