Table 3 Linear mixed effects model summary for force sample entropy (irregularity)

Fixed effects

Estimate (SE)

df

t

Partial R²

SampEn

Intercept

.274 (.0114)

64.7

24.110***

Level 1

 Gain_{Low vs. Med & High}

−.0598 (.0088)

301.0

−6.835***

.050

 Gain_{Low & Med vs. High}

−.0209 (.0088)

301.0

−2.376*

.006

 Vibration

.0053 (.0073)

305.9

.720

.001

Level 2

 Group

−.0209 (.0227)

64.7

−.921

.009

 Age

.0713 (.0109)

64.4

6.521***

.324

Interactions

 Group × Gain_{Low vs. Med & High}

.0012 (.0175)

301.0

.068

<.001

 Group × Gain_{Low & Med vs. High}

.0120 (.0176)

301.0

.681

.001

 Group × Vibration

.0208 (.0147)

305.9

1.416

.002

 Group × Age

.0875 (.0219)

64.4

4.005***

.153

 Gain_{Low vs. Med & High} × Age

−.0102 (.0084)

301.3

−1.219

.002

 Gain_{Low & Med vs. High} × Age

.0027 (.0085)

301.3

.318

<.001

 Vibration frequency × Age

−.0046 (.0069)

303.4

−.658

<.001

 Group × Gain_{Low vs. Med & High} × Age

−.0534 (.0168)

301.3

−3.223**

.011

 Group × Gain_{Low & Med vs. High} × Age

.0161 (.0169)

301.3

.955

.001

 Group × Vibration × Age

.0342 (.0139)

303.4

2.460*

.007

Random effects

Estimate (SD)

Participant (intercept)

.0067 (.0816)

 Residual

.0042 (.0645)