Table 2 Spatiotemporal parameters of gait analysis and functional motor assessment of participants with PD (Sham vs. Gondola®) at first intervention (6 sessions of stimulation) (T1-T2)

Primary outcome

 Velocity [m/s]

0.62 ± 0.19

0.68 ± 0.21

0.66 ± 0.21

0.87 ± 0.24

0.04 ± 0.13

0.19 ± 0.21

 < 0.001

Secondary outcomes

 Spatiotemporal parameters of gait analysis

Cadence [stride/min]

103.15 ± 15.33

103.04 ± 14.60

103.95 ± 15.66

107.48 ± 13.79

0.79 ± 16.97

4.44 ± 9.74

0.271

Stride length [m]

0.75 ± 0.23

0.80 ± 0.22

0.78 ± 0.22

0.98 ± 0.23

0.03 ± 0.17

0.18 ± 0.22

0.002

% Stride length

46.46 ± 14.03

49.07 ± 12.49

48.32 ± 13.81

59.84 ± 12.06

1.86 ± 10.42

10.77 ± 13.58

0.003

Stride duration [s]

1.21 ± 0.16

1.21 ± 0.19

1.20 ± 0.18

1.15 ± 0.21

− 0.012 ± 0.18

− 0.059 ± 0.12

0.212

Stance phase [%]

61.94 ± 2.53

61.54 ± 2.76

61.57 ± 2.61

60.87 ± 2.60

− 0.376 ± 2.91

− 0.672 ± 2.78

0.660

Swing phase [%]

38.05 ± 2.53

38.46 ± 2.76

38.43 ± 2.61

39.13 ± 2.60

0.376 ± 2.91

0.672 ± 2.78

0.660

Initial phase of double support [%]

11.83 ± 2.59

11.54 ± 2.75

11.40 ± 2.62

10.84 ± 2.48

− 0.424 ± 2.97

− 0.70 ± 2.85

0.687

Single support phase [%]

38.21 ± 2.66

38.44 ± 2.73

38.54 ± 2.61

39.17 ± 2.53

0.336 ± 2.94

0.732 ± 2.81

0.562

Propulsion [m/s²]

3.76 ± 1.34

3.85 ± 1.33

3.81 ± 1.43

4.64 ± 1.43

0.045 ± 1.11

0.793 ± 1.51

0.019

 Functional motor assessments

FOG-Q (0–24)

10.62 ± 4.80

11.76 ± 4.69

10.52 ± 4.73

10.32 ± 4.46

− 0.11 ± 1.52

− 1.44 ± 2.27

0.005

TUG [s]

22.40 ± 8.36

25.54 ± 17.11

22.94 ± 10.24

22.60 ± 24.92

0.54 ± 6.72

− 2.94 ± 11.59

0.121

TUG Dual-task [s]

28.97 ± 11.94

39.71 ± 53.49

31.97 ± 16.44

35.86 ± 55.22

3.00 ± 13.15

− 3.85 ± 20.96

0.099

Mini-BESTest (0–28)

14.83 ± 5.21

15.34 ± 4.46

14.76 ± 4.98

16.14 ± 4.42

− 0.08 ± 1.23

0.80 ± 1.54

0.009

MDS-UPDRS

 − 2.12

1.73 ± 0.92

1.83 ± 0.89

1.67 ± 0.94

1.65 ± 0.87

− 0.05 ± 0.57

− 0.17 ± 0.51

0.365

 − 2.13

1.32 ± 1.04

1.60 ± 1.00

1.29 ± 1.02

1.34 ± 1.00

− 0.027 ± 0.50

− 0.26 ± 0.61

0.084

 − 3.10

2.19 ± 0.83

2.03 ± 0.77

2.16 ± 0.87

1.67 ± 0.76

− 0.027 ± 0.37

− 0.36 ± 0.60

0.006

 − 3.11

1.35 ± 1.25

1.36 ± 1.06

1.35 ± 1.18

1.00 ± 0.98

0.01 ± 0.47

− 0.36 ± 0.65

0.009

 − 3.12

2.00 ± 1.00

2.03 ± 1.12

2.13 ± 1.03

1.67 ± 1.21

0.13 ± 0.42

− 0.36 ± 0.49

 < 0.001