*3.2. Measurement Chain*

Basographic and sEMG signals were acquired and synchronized by means of Step 32 multichannel recording system, (Medical Technology, Turin, Italy, resolution: 12 bit; sampling rate: 2 kHz). Basographich switches (minimum activation force = 3 N), were pasted beneath the heel, the first and the fifth metatarsal heads of each foot, for measuring foot–floor-contact signal. Single di fferential sEMG probes (Ag/Ag-Cl disk; electrode diameter: 0.4 cm; inter-electrode distance: 0.8 cm; di fferential amplifier gain: 30 dB; high-pass filter cut-o ff frequency: 10 Hz; input impedance: 1.5 G Ω; CMRR > 126 dB; input referred noise: 1 Vrms) were placed bilaterally over TA and GL muscles, following acknowledged guidelines [32,33]. Then, subjects walked barefoot back and forth over the floor at preferred speed and pace for at least 2.5 min. Further details about acquisition procedure could be found in [4,35,36].
