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. Author manuscript; available in PMC: 2020 Nov 3.
Published in final edited form as: Gait Posture. 2019 Mar 14;70:376–382. doi: 10.1016/j.gaitpost.2019.02.034

Table 2.

Stride-to-stride fluctuations (α) and adaptive response during and post-perturbation across enforced step frequency perturbation levels.

150 160 170 180 190 Overall
Difference from PSF (%) −8.6 ± 5.3 −2.5 ± 5.7 3.6 ± 6.02 9.7 ± 6.4 15.8 ± 6.7
Perturbation
Step rate a 0.78 ± 0.19b 0.68 ± 0.21a 0.60 ± 0.2a,b 0.65 ± 0.22 0.67 ± 0.22 0.68 ± 0.22
Contact time a 0.73 ± 0.13 0.73 ± 0.18 0.68 ± 0.11 0.73 ± 0.12 0.73 ± 0.12 0.72 ± 0.14
Time to plateau (s) 2.89 ± 0.71 2.79 ± 0.77 2.74 ± 0.57 2.70 ± 0.66a 2.54 ± 0.63a 2.7 ± 0.68
Time to reach ESF (s) c 107.8 ± 124.3 134.3 ± 125.7 186.9 ± 111a 167.3 ± 119.4a 207 ± 97.7a 160.6 ± 121.3
ESF match (spm) 5.2 ± 11.2 −1.3 ± 7.5a −5.1 ± 7.7a −8.9 ± 4.9a −13.4 ± 6.4a −4.7 ± 10.1
Post- Perturbation
Step rate a 0.69 ± 01.5 0.69 ± 0.17 0.66 ± 0.18 0.66 ± 0.17 0.69 ± 0.14 0.68 ± 0.16
Contact time a 0.71 ± 0.14 0.69 ± 0.09 0.73 ± 0.12 0.69 ± 0.10 0.70 ± 0.11 0.70 ± 0.11
Time to plateau (s) 2.4 ± 0.79 2.65 ± 0.77a 2.63 ± 0.66 2.65 ± 0.76a 2.42 ± 0.73 2.6 ± 0.7
Time to return to PSF (s)c 35.2 ± 111.7 2.7 ± 0.83a 24.8 ± 92.4 2.9 ± 0.74a 13.9 ± 66.2a 15.9 ± 0.7
Step frequency drift (spm) 1.9 ± 2.9 1.8 ± 1.9 1.5 ± 2.2 0.54 ± 1.7a 0.12 ± 2.5a 1.2 ± 2.4

spm = steps per minute.

a

Significant difference from novice group (p < 0.05).

b

Significant difference from experienced group (p < 0.05).