Supplementary Table S8. Boundary-free nominal 4.0-second analytical-window analysis after removal of the lifting-to-lowering analytical boundary.
Panel A. Attachment omnibus tests in the boundary-free nominal 4.0-second analytical-window analysis.
Muscle Rows, n Participants, n Conditions, n Wald χ2 df p
PD 86 14 46 13.75 3 0.003
BB 82 13 44 25.05 3 < 0.001
TB 88 14 47 10.01 3 0.018
MT 83 13 43 13.71 3 0.003
LD 84 13 45 4.72 3 0.194
Boundary-free models used a continuous nominal 4.0-second window beginning at the same participant-specific fixed 20% right-LD EMG-defined activity onset (50-ms moving RMS envelope; at least 50-ms threshold persistence), with attachment as a fixed effect and participant as a random intercept. The phase term was not included. This analysis removes the lifting-to-lowering analytical boundary but does not identify the true mechanical cycle.

Panel B. Prespecified attachment contrasts in the boundary-free nominal 4.0-second analytical-window analysis.
Muscle / contrast Boundary-free 4.0-s estimate [95% CI] Bonferroni-adjusted p
PD: RP-CB 7.15 [3.15, 11.15] 0.003
BB: WVS-SB 2.22 [-0.85, 5.29] 0.937
BB: WVS-CB 1.34 [-1.81, 4.48] 1.000
BB: WVS-RP 6.70 [3.63, 9.77] < 0.001
TB: WVS-CB 8.09 [2.80, 13.38] 0.016
TB: WVS-RP 3.33 [-1.73, 8.40] 1.000

Bonferroni correction was applied across the six prespecified contrasts. The original middle-trapezius lifting-versus-lowering analytical-interval contrast is not estimable after removal of the phase term and therefore is not confirmed by this analysis. The LD boundary-free attachment omnibus test was not significant (p = 0.194).