## 3 Results
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multicolumn{3}{c}{**Young Women**} & \multicolumn{3}{c}{**Older Women**} & \multicolumn{3}{c}{**Young vs. Older Women**} \\ \hline  & _10 cm vs._ & _20 cm vs._ & _10 cm vs._ & _10 cm vs._ & _20 cm vs._ & _10 cm vs._ & _10 cm_ & _20 cm_ & _30 cm_ \\  & _20 cm_ & _30 cm_ & _30 cm_ & _20 cm_ & _30 cm_ & _30 cm_ & _10 cm_ & _20 cm_ & _30 cm_ \\ \hline \multicolumn{3}{c}{**Fstep Correlation coefficients (r)**} \\ \hline _Synergy 1_ & 0.64 & 0.56 & 0.57 & 0.52 & 1.76 & 0.58 & 0.61 & 0.02 & 0.69 \\ _Synergy 2_ & 0.64 & 0.56 & 0.57 & 0.58 & 0.58 & 0.59 & 0.76 & 0.78 \\ _Synergy 3_ & 0.44 & 0.70 & 0.89 & 0.72 & 0.43 & 0.85 & 0.83 & 0.71 & 0.88 \\ _Synergy 4_ & 0.56 & 0.55 & 0.59 & 0.59 & 0.58 & 0.58 & 0.58 & 0.74 \\ \hline \multicolumn{3}{c}{**Lstep Correlation coefficients (r)**} \\ \hline _Synergy 1_ & 0.54 & 0.48 & 0.38 & 0.56 & 0.55 & 0.54 & 0.48 & 0.67 & 0.03 \\ _Synergy 2_ & 0.61 & 0.50 & 0.40 & 0.58 & 0.51 & 0.55 & 0.19 & 0.51 & 0.79 \\ _Synergy 3_ & 0.50 & 0.43 & 0.15 & 0.58 & 0.53 & 0.71 & 0.90 & 0.58 & 0.29 \\ _Synergy 4_ & 0.70 & 0.66 & 0.55 & 0.70 & 0.64 & 0.80 & 0.90 & 0.76 & 0.76 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Similarity index (Pearson’s _r_) of synergy weightings, across step heights for each age group, and across age groups for each step height. Results are displayed separately for forward stepping (Fstep) and lateral stepping (Lstep). Grey = marginal similarity (\(r>0.45\)) and black = significant similarity (\(r>0.7\)). Figure 2: Averaged variance accounted for (VAF) by number of extracted synergies at step heights of 10, 20 and 30 cm in forward (Fstep) and lateral (Lstep) stepping directions for young and older women. The appropriate number of synergies was defined as the least number of synergies required to reach \(>\)85% VAF (indicated by dashed lines) and a reconstruction quality of \(\geq\)75% VAF for each individual muscle. Figure 3: Muscle weightings and temporal activation patterns for four synergies (**S1**–**S4**) extracted during forward stepping (Fstep). Each set of two columns represents muscle synergies extracted from step heights of 10, 20 or 30 cm per age group with young women represented in the left column and older women in the right column. * indicates a significant difference between contributions of individual muscles between age groups. Time-averaged foot clearance (white bars) and pull-up (black bars) phases of ascent are depicted at the bottom. TA = tibialis anterior, GL = gastrocnemius lateralis, SOL = soleus, VL = vastus lateralis, RF = rectus femoris, BF = biceps femoris, ST = semientdinosus, GMAX = gluteus maximums, GMED = gluteus mediums, ERS = encoder Spine. Figure 4: Muscle weightings and temporal activation patterns for four synergies (**S1–S4**) extracted during lateral stepping (Lstep). Each set of two columns represents muscle synergies extracted from step heights of 10, 20 or 30 cm per age group with young women represented in the left column and older women in the right column. * indicates a significant difference between contributions of individual muscles between age groups. Time-averaged foot clearance (white bars) and pull-up (black bars) phases of ascent are depicted at the bottom. TA = tibialis anterior, GL = gastrocnemius lateralis, SOL = soleus, VL = vastus lateralis, RF = rectus femoris, RF = biceps femoris, ST = semiemedinosus, GMAX = glutesis maximus, GMED = glutesis medius, ERS = erector Spinae. Analyses of the temporal activation patterns (Figures 3 and 4) and the time-averaged standard deviation of these temporal activation patterns (Figure 5) showed that the between-subject variability of activation timing for most step heights and directions was significantly higher in the older cohort.