Biomedical Engineering Reference
In-Depth Information
95% of the variance in the EMG. We found that in all cases only one or two PCs
were needed and that this did not differ between post-stroke and healthy subjects.
Therefore, we have no evidence that post-stroke subjects are any more limited in
their ability to modify patterns of muscle activation than aged-matched healthy
subjects. Because PC1 always accounted for more than 75% of the variance, we
concluded that the individual exercises were generally performed using only one
predominant pattern of muscle activation, both in the case of healthy and post-
stroke subjects.
Although only one PC accounted for most of the variance, the profile of this PC
(PC1) was quite different for exercises performed with the HandCARE compared
to the HapticKnob (
Fig. 4.7(A)
) Given that the RMS-EMG was normalized with
respect to maximal voluntary contraction prior to conducting the principal com-
ponent analysis, the weighting coefficients of PC1 represent the relative activation
of eachmuscle in the predominant activation pattern. In the example of
Fig. 4.7(A)
,
which represents muscle activity patterns prior to the robot-assisted rehabilitation,
the PC1 profile shows that the forearm supinator, biceps (BI), and the finger
abductor, first dorsal interosseus (1DI), are the primary muscles contributing to the
pattern for the HapticKnob exercises training grasping and pronation/supination.
For the HandCARE exercises training finger movement coordination, all of the
finger muscles (1DI, FDS, EDC, ADM) contribute relatively equally and their
contribution is greater than that of the wrist muscles (ECR and FCU). However,
the biceps is the most active muscle, which represents abnormal activation. After
the robot-assisted rehabilitation (
Fig. 4.7(B)
)
the activity of the biceps activity in
PC1 was the lowest of all the muscles, indicating that this aspect of the abnormal
activation patterns had improved with the robot-assisted rehabilitation.
B
A
0.8
0.8
Haptic Knob, PC1=78.3%
HandCARE, PC1=94.6%
before, PC1=94.6%
after, PC1=90.2%
0.7
0.7
0.6
0.6
0.5
0.5
0.4
0.4
0.3
0.3
0.2
0.2
0.1
0.1
0
0
ECR
EDC
FCU
FDS
PT
BI
1DI
ADM
ECR
EDC
FCU
FDS
PT
BI
1DI
ADM
Figure 4.7
PC1 of a stroke patient (P1) pre-rehab muscle activity from PCAs for exercises
with the HapticKnob and with the HandCARE (A). Comparison of PC1 of a stroke patient
(P1) muscle activity during a grasping exercise with the HandCARE before and after robot-
assisted therapy (B).
