# Establishing Reference Data for Electromyographic Activity in Gait: Age and Gender Variations
## 4 Discussion  
This study addressed the lack of age- and gender-specific EMG reference data for gait analysis, which are crucial for distinguishing typical from pathological patterns for clinical gait analysis. We aimed to quantify age- and gender-related differences in lower-limb myoelectric activity during walking in typically developing individuals. By applying the SPM approach to EMG envelopes, we were able to capture differences across the entire gait cycle, preserving important information that could be lost through averaging. To further explore these differences, we conducted an analysis of the interaction effect between age and gender, followed by a power analysis to determine the minimum number of subjects required for establishing comprehensive reference data in the clinic. The observed differences in gait mechanics between children and adults highlight distinct neuromuscular strategies influenced by developmental factors. Children exhibited a greater cadence but slower walking speed, shorter stride time, and shorter stride length, accompanied by larger peak hip flexion and greater activation of the rectus femoris in initial swing and the hamstrings in the midstance. Higher cadence with shorter strides reflects a reliance on more frequent, smaller steps to maintain stability and forward progression, \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{\begin{tabular}{c} **Dependent** \\ **Variable** \\ \end{tabular} } & \multirow{2}{*}{**Age Group**} & \multirow{2}{*}{**Gender Group**} & \multirow{2}{*}{**Mean (SD)**} & \multicolumn{2}{c}{\begin{tabular}{c} **95\% Confidence** \\ **Interval** \\ **(Lower-Upper** \\ **Bound)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **\(p\) Value for** \\ **Pairwise** \\ **Comparisons** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **\(p\) Value for** \\ **Intersection** \\ **Age-Gender** \\ \end{tabular} } & \multirow{2}{*}{\multirow{2}{*}{\begin{tabular}{c} **Cohen’s f** \\ **Age-Gender** \\ \end{tabular} } \\ \cline{5-8}  & & & Male & 90.4 (2.7) & 84.9-95.9 & \multirow{2}{*}{0.056} & \multirow{2}{*}{0.002} & \multirow{2}{*}{0.141} \\ \cline{4-4} \cline{6-8}  & & Female & 81.9 (3.3) & 75.2-88.7 & & & \\ \cline{2-8}  & & & Male & 79.1 (2.3) & 74.3-83.7 & & & \\ \cline{2-8}  & & Female & 88.1 (2.2) & 83.7-92.5 & & & \\ \hline \multirow{2}{*}{\begin{tabular}{c} Mean activity of \\ BIC in swing \\ \end{tabular} } & \multirow{2}{*}{Children} & Male & 116.9 (17.8) & 108.5-125.3 & & & \\ \cline{2-8}  & & Female & 130.9 (14.6) & 120.6-141.2 & & & \\ \cline{2-8}  & & Male & 136.8 (23) & 129.6-144 & & & \\ \cline{2-8}  & & Female & 121 (18.7) & 114.2-127.7 & & & \\ \hline \multirow{2}{*}{\begin{tabular}{c} Maximum activity of \\ BIC in swing \\ \end{tabular} } & \multirow{2}{*}{Children} & Male & 278.5 (61.8) & 247.5-309.3 & & & \\ \cline{2-8}  & & Female & 314.1 (46.5) & 276.2-351.9 & & & \\ \cline{2-8}  & & Male & 340.6 (85.4) & 314.3-366.9 & \multirow{2}{*}{\(<\)0.001} & \multirow{2}{*}{0.199} \\ \cline{2-8}  & & Female & 268 (71.7) & 243.3-292.6 & & & \\ \hline \multirow{2}{*}{\
\begin{tabular}{c} Mean activity of \\ SEM in stance \\ \end{tabular} } & \multirow{2}{*}{Children} & Male & 85.1 (2.9) & 79.2-91 & & & \\ \cline{2-8}  & & Female & 76.2 (3.6) & 69-83.4 & & & \\ \cline{2-8}  & & Male & 71.2 (2.5) & 66.2-76.3 & & & \\ \cline{2-8}  & & Female & 78.6 (2.3) & 73.9-83.3 & & & \\ \hline \multirow{2}{*}{
\begin{tabular}{c} Mean activity of \\ SEM in swing \\ \end{tabular} } & \multirow{2}{*}{Children} & Male & 126.1 (4.6) & 116.9-135.4 & & & & \\ \cline{2-8}  & & Female & 138.6 (5.6) & 127.3-149.9 & & & \\ \cline{2-8}  & & Male & 148.5 (3.9) & 140.6-156.4 & & & \\ \cline{2-8}  & & Female & 135.4 (3.7) & 128.1-142.8 & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Mean (SD) and statistical results for the interaction effect between age and gender groups. BIC: biceps femoris, SEM: semimembranosus. Only variables with a significant interaction effect (\(p<0.0125\)) are presented.