Fig 1.
Slant board mounted on the force plate in all different experimental conditions.
Horizontal (H0, reference condition), dorsal flexion at 7° (DF7) and 15° (DF15), plantar flexion at 7° (PF7) and 15° (PF15).
Fig 2.
EMG electrodes placement of the three tested muscles.
Fig 3.
Subject equipped with EMG electrodes standing on the slant board in a DF15 condition.
Fig 4.
Normalized EMG (% maximal voluntary contraction, or MVC) as a function of surface slope.
EMG of tibialis anterior (TA), soleus (Sol) and gastrocnemius medialis (GasM) are presented in each condition of surface slope: horizontal (H0), dorsal flexion at 7° (DF7) and 15° (DF15), and plantar flexion at 7° (PF7) and 15° (PF15), (*p <0.05, **p <0.01 and ***p <0.001).
Fig 5.
Representative traces of the 30-s rectified EMG signal of the soleus (Sol).
Data are presented in mV in each surface slope condition: horizontal (H0), dorsal flexion at 7° (DF7) and 15° (DF15), and plantar flexion at 7° (PF7) and 15° (PF15).
Table 1.
Mean rectified EMG of tibialis anterior (TA), gastrocnemius medialis (GasM) and soleus (Sol) in each surface slope condition.
Fig 6.
Representative traces of 30-s CP trajectory in each experimental condition.
From left to right: dorsal flexion at 15° (DF15) and 7° (DF7), Horizontal (H0), and plantar flexion at 7° (PF7) and 15° (PF15). Y represents the medial-lateral axis, and X the anterior-posterior axis.
Fig 7.
Mean position of CP along the anterior-posterior (X0) (A) medial-lateral (Y0) (B) axes as a function of surface slope. Means and standard deviations are presented for each experimental condition: horizontal (H0), dorsal flexion at 7° (DF7) and 15° (DF15), and plantar flexion at 7° (PF7) and 15° (PF15), (*p <0.05, **p <0.01 and ***p <0.001).
Table 2.
Posturographic parameters as a function of surface slope.
Fig 8.
Mean CP displacements along the anterior-posterior (Xm) (A) and medial-lateral (Ym) (B) axes as a function of surface slope. Means and standard deviations are presented in each experimental condition: horizontal (H0), dorsal flexion at 7° (DF7) and 15°, and plantar flexion at 7° (PF7) and 15° (PF15), (*p <0.05 and **p <0.01).
Fig 9.
Mean velocity of CP displacements in the horizontal plane (Vm) in each experimental condition.
Means and standard deviations are presented for all experimental conditions: horizontal (H0), dorsi flexion at 7° (DF7) and 15°, and plantar flexion at 7° (PF7) and 15° (PF15), (**p < 0.01).