Supplementary file 1_Bilateral lower-limb asymmetry and phase-specific trunk acceleration during the Timed Up and Go in older women: an analysis based on muscle morphology and antagonist coactivation.docx

No significant group-level left–right differences in muscle thickness were detected, although ASI exceeded 15% for all four muscles. After FDR correction, significant bilateral differences were retained for mean CCI_QUAD-BF during sit-to-stand (p< 0.001, q = 0.005), mean CCI_TA-MG during sit-to-stand (p = 0.001, q = 0.013) and peak CCI_QUAD-BF during sit-to-stand (p = 0.002, q = 0.013); the difference for mean CCI_QUAD-BF during return walk (p = 0.016) did not survive correction.

Coactivation ASI was generally higher at the knee than the ankle. After Benjamini–Hochberg false discovery rate correction, three peak coactivation asymmetry correlations with RMS_AP survived: peak ASI_TA-MG during outbound walk (r = 0.72, q< 0.001), peak ASI_QUAD-BF during turn (r = 0.53, q = 0.043) and peak ASI_TA-MG during sit-to-sit (r = 0.57, q = 0.044). The negative correlations of ASI_MG with RMS_AP during sit-to-stand and outbound walk (r = −0.52, r = −0.51) did not survive FDR correction.

No ASI correlated significantly with RMS_ML. Bilateral asymmetry was heterogeneous in direction, and phase-specific peak coactivation asymmetry was more consistently associated with anteroposterior trunk acceleration than muscle thickness. These measures may provide complementary information beyond muscle morphology or total TUG time, but their reliability and clinical relevance require further investigation.</p>