Table 4.

Statistical outcomes for the construct validity evaluation

Parameters	TD	CP	Ppert	Pintensity	Pgroup	Pinter
Max Δangle (°)
Ankle	5.40 ± 1.34	3.79 ± 1.40	< 0.001	< 0.001	0.028	0.002
Knee	4.41 ± 1.64	4.50 ± 1.90	< 0.001	< 0.001	0.153	0.430
Max ΔMTL (norm.)
GM	2.99 ± 0.52	2.15 ± 1.05	< 0.001	< 0.001	0.006	0.038
SO	3.60 ± 0.89	2.42 ± 1.02	< 0.001	< 0.001	0.016	0.001
TA	− 3.56 ± 0.81	− 2.49 ± 1.05	< 0.001	< 0.001	0.028	0.002
Max ΔMTV (norm.)
GM	25.04 ± 4.04	23.05 ± 5.57	< 0.001	< 0.001	0.682	0.178
SO	37.51 ± 7.40	29.76 ± 9.78	< 0.001	< 0.001	0.057	0.011
TA	− 35.14 ± 5.36	− 28.72 ± 8.53	< 0.001	< 0.001	0.085	0.006
Max ΔEMG (%)
GM	230.92 ± 67.91	359.53 ± 189.63	< 0.001	< 0.001	0.018	0.051
SO	285.10 ± 160.90	282.69 ± 149.86	< 0.001	< 0.001	0.540	0.537
TA	106.47 ± 39.83	189.88 ± 204.63	0.003	0.001	0.131	0.126
CCI difference
GM	− 0.09 ± 0.06	0.01 ± 0.06	< 0.001	0.069	0.001	0.076
SO	− 0.07 ± 0.05	− 0.01 ± 0.05	< 0.001	0.001	< 0.001	0.742
Muscular response strength (norm.)
GM	9.95 ± 3.74	16.96 ± 8.81	0.658	0.501	0.064	0.045
SO	8.52 ± 5.65	11.10 ± 5.05	0.521	0.237	0.005	0.351
Muscular response duration (ms)
GM	102.95 ± 7.47	124.57 ± 15.39	< 0.001	< 0.001	< 0.001	0.001
SO	93.88 ± 8.65	114.07 ± 16.70	< 0.001	< 0.001	0.004	0.001

Values for the highest intensity are presented for all construct validity parameters. Values for unperturbed and the three intensities are presented in Additional file 1: Table S1. Abbreviations: with TD the typically developing group, CP the cerebral palsy group, P_pert the effect of perturbations (Helmert contrast), P_intensity the effect of intensities (linear polynomial contrast), P_group the difference between CP and TD, P_inter the interaction between CP and TD, MTL musculo-tendon length, GM gastrocnemius medialis muscle, SO soleus muscle, TA tibialis anterior muscle, MTV musculo-tendon stretch velocity, CCI diff difference in co-contraction index between unperturbed and highest intensity perturbations. Mean ± standard deviations are presented. Significant p-values are expressed in bold