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Table 2 Root mean square error (RMSE) values and Pearson correlation coefficient (r) values for estimated muscle activations calculated between the experimental (“Params”) case and each calibration case

From: Comparison of synergy extrapolation and static optimization for estimating multiple unmeasured muscle activations during walking

Unmeasured Muscles

Calibration cases

\(\begin{gathered} S{\text{yn}}X_{Unmeasured} \hfill \\ + Params \hfill \\ \end{gathered}\)

\(S{\text{yn}}X_{{_{Unmeasured} }}^{Params}\)

\(SO_{{_{All} }}^{Generic}\)

\(SO_{{_{All} }}^{Params}\)

\(SO_{{_{Unmeasured} }}^{Params}\)

RMSE

r

RMSE

r

RMSE

r

RMSE

r

RMSE

r

Adductor brevis

0.02

0.54

0.01

0.69

0.04

− 0.17

0.02

− 0.03

0.02

0.37

Adductor longus

0.02

0.60

0.01

0.83

0.11

− 0.13

0.02

0.12

0.04

0.37

Adductor magnus distal

0.02

0.53

0.01

0.84

0.03

0.01

0.03

− 0.07

0.03

− 0.11

Adductor magnus ischial

0.02

0.55

0.01

0.89

0.04

0.23

0.04

− 0.08

0.11

0.32

Adductor magnus middle

0.02

0.43

0.01

0.63

0.02

− 0.17

0.02

− 0.15

0.02

0.26

Adductor magnus proximal

0.04

0.58

0.01

0.76

0.03

− 0.14

0.04

− 0.21

0.19

0.47

Iliacus

0.17

0.43

0.17

0.86

0.24

0.05

0.21

0.08

0.33

0.04

Psoas

0.14

0.45

0.17

0.78

0.30

0.02

0.25

0.07

0.16

0.50

Rectus femoris

0.09

0.63

0.06

0.76

0.21

0.35

0.14

0.30

0.21

0.11

Tensor fasciae latae2

0.16

0.66

0.04

0.98

0.29

− 0.09

0.24

− 0.15

0.15

0.71

Vastus medialis

0.09

0.65

0.02

0.92

0.07

0.13

0.05

0.79

0.10

0.61

Vastus intermedius

0.08

0.67

0.02

0.92

0.08

0.12

0.06

0.81

0.08

0.59

Lateral gastrocnemius2

0.09

0.62

0.04

0.79

0.09

0.18

0.07

0.48

0.08

0.67

Tibialis posterior

0.15

0.53

0.08

0.58

0.11

0.53

0.13

0.54

0.20

0.16

Peroneus brevis

0.08

0.41

0.05

0.74

0.15

− 0.31

0.07

0.29

0.11

0.25

Peroneus longus

0.09

0.42

0.05

0.79

0.13

0.13

0.06

0.43

0.14

0.25

Extensor digitorum longus1

0.17

0.38

0.08

0.42

0.62

0.48

0.08

0.09

0.15

0.21

Flexor digitorum longus1

0.05

0.92

0.09

0.82

0.14

0.89

0.11

0.95

0.11

0.38

Mean ± standard deviation

0.08 ± 0.06

0.55 ± 0.13

0.05 ± 0.05

0.78 ± 0.14

0.15 ± 0.15

0.12 ± 0.30

0.09 ± 0.07

0.24 ± 0.36

0.12 ± 0.08

0.34 ± 0.22

  1. The RMSE and r values were calculated when the data across all calibration trials and subjects were concatenated
  2. 1Indicates the EMG signals were assumed unmeasured only for S1 and 2indicates the EMG signals were assumed unmeasured only for S2