O. Chialà et al
Fig. 3. 3-D scatter plot of correlations among 6-min walk test (6MWT),
muscle function test (MFT) (shoulder abduction) and Duke Activity Status
Index (DASI), in the presence of arm impairment.
analysis, which showed the presence of 2 different fac-
tors, was performed (Table V). The correlation matrix
was suited for factor analysis (Bartlett’s test of sphe-
ricity = 368.498; df = 21; p < 0.001; KMO = 0.776). As
shown in Table V, factor I included the 6MWT, number
of right heel-lifts, number of left heel-lifts, and DASI
612
score. Factor II included resistance during shoulder
abduction, the number of right shoulder flexions and
left shoulder flexions. The 2 factors are referred to as
“lower limbs capacity” and “upper limbs capacity”,
respectively. Together, these factors explained 58% of
the total variance of the measured variables.
These results indicate that physical fitness, exercise
capacity, muscle function and functional capacity
assessment were clearly bi-dimensional, with a first
factor that included only lower limbs capacity and a
second factor that included only upper limbs capacity.
Table V. Results of exploratory principal component analysis with
promax rotation (n = 96)
Components
Fig. 4. 3-D scatter plot of correlations among 6-min walk test (6MWT),
muscle function test (MFT) (right shoulder flexion) and Duke Activity
Status Index (DASI), in the presence of right arm impairment.
6-min walk test
Right heel-lift
Left heel-lift
Shoulder abduction
Right shoulder flexion
Left shoulder flexion
Duke Activity Status Index
Variance explained, %
1 2
0.594
0.929
0.995
0.023
−0.074
0.120
0.416
54 0.221
0.017
−0.136
0.802
0.942
0.737
0.237
14
Factor loadings higher than 0.05 are shown in bold.
Table IV. Correlation matrix for limb impairment and exercise capacity, muscle function and functional capacity (n = 96)
Muscle function test
a
Right leg impaired
Left leg impaired a
a
Right arm impaired
Left arm impaired a
Fig. 5. 3-D scatter plot about correlations among 6-min walk test
(6MWT), muscle function test (MFT) (left shoulder flexion) and Duke
Activity Status Index (DASI), in the presence of left arm impairment.
6MWT RHL LHL SA RSF LSF DASI
−0.360** −0.541** −0.452** −0.246 −0.220 −0.225 −0.208
−0.308** −0.446** −0.541** −0.146 −0.124 −0.147 −0.161
−0.058 −0.055 −0.010 −0.415** −0.498** −0.368** −0.072
−0.032 −0.111 −0.083 −0.370** −0.376** −0.548** −0.081
**p < 0.001.
Variable dichotomized: 0 = no impairment; 1 = impairment.
Bonferroni correction: new p-value fixed at < 0.007.
6MWT: 6-min walk test; RHL: right heel-lift; LHL: left heel-lift; SA: shoulder abduction; RSF: right shoulder flexion; LSF: left shoulder flexion; DASI: Duke Activity
Status Index.
a
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