# Establishing Reference Data for Electromyographic Activity in Gait: Age and Gender Variations
## 2 Materials and Methods
### Instrumentation and Protocol  
All the participants walked barefoot at a self-selected speed along a 15 m walkway during data acquisition. Kinematic and kinetic data were recorded using a 12-camera 3D motion analysis system (VICON, Oxford Metrics Limited, Oxford, UK) operating at  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Age Group** & **Gender Group** & **No.** & **Age (Years)** & **Age Range (Min–Max)** & **Height (cm)** & **Body Mass (kg)** & **Body Mass Index (BMI) (kg/m2)** \\ \hline \multirow{3}{*}{Children} & Male & 21 & 9.36 (1.77) & 5.7–12.7 & 137.76 (11.89) & 33.02 (88.82) & 17.04 (2.14) \\ \cline{2-7}  & Female & 14 & 9.28 (2.19) & 5.6–12.6 & 138.42 (15.16) & 34.37 (13.78) & 17.02 (4.06) \\ \hline \multirow{3}{*}{Adults} & Male & 29 & 31.42 (10.86) & 21.2–64.1 & 180.55 (7.16) & 77.25 (8.71) & 23.69 (2.33) \\ \cline{2-7}  & Female & 33 & 28.7 (11.03) & 18.2–62.6 & 168.84 (11.03) & 62.88 (7.6) & 22.04 (2.17) \\ \hline \hline \end{tabular}
\end{table}
Table 1: Demographic characteristics of age and gender groups.  
Figure 1: Age and gender distribution of participants.  
120 Hz and three force plates operating at 1080 Hz (Kistler Instruments Co., Winterthur, Switzerland). Skin-mounted markers were placed according to the protocol of [PERSON] et al. [19], and the Plug-in-Gait (PiG) model was used for analysis.  
EMG data were collected from seven major lower-extremity muscles: the tibialis anterior (TIB), soleus (SOL), gastrocnemius lateralis (GAS), rectus femoris (REF), vastus lateralis (VAS), biceps femoris (BIC), and semimembranosus (SEM) of both legs. Data acquisition was performed using the Myon 320 system (Myon AG, Schwarzenberg, Switzerland). Bipolar surface adhesive electrodes (Blue Sensor, Ambu Inc., Glen Burnie, MD, USA) were placed on the target muscles following SENIAM guidelines [20], with an inter-electrode distance of 2 cm [21]. To amplify the EMG signal, the Biovision EMG apparatus (Biovision Inc., Wehrheim, Germany) was used before 2013/14, and Delsys systems (Delsys Inc., Natick, MA, USA) were used after 2013/14, with a preamplification factor of \(\times\)5000. Skin-based EMG signal detection was performed at 1000 Hz. An extensive quality check analysis was conducted to assess potential technological variations between the two systems. No significant differences were observed in the recorded EMG patterns between the systems. Additionally, the same normalization algorithm was applied to the signals from both systems to ensure consistency in data processing.  
We extracted gait data from at least seven trials, each including one gait cycle typically around the force plate, where participants exhibited consistent gait patterns, and then calculated average values across all trials for each patient. To ensure the analysis was based on steady-state walking, the initial and final gait cycles of the 15 m walkway were excluded. This approach minimized the influence of acceleration and deceleration phases on the EMG and gait data. The data were collected under the supervision of a professional operator in our lab. The raw EMG data were first assessed by the experienced operator, followed by post-processing. There are several projects and papers involving assessment of EMG data in the Heidelberg motion lab that prove the reliability and robustness of the collected data [1; 2; 3; 4; 21; 22].