Relationships among measures of physical fitness in adults with heart failure
611
Table III. Correlation matrix (n = 96)
Muscle function test
6MWT
6MWT
Muscle function tests
RHL
LHL
SA
RSF
LSF
DASI
Age
Sex a
NYHA
EF
RHL LHL SA RSF LSF DASI
Age
0.691**
0.608**
0.511**
0.423**
0.447**
0.531**
−0.335** 1
0.861**
0.452**
0.472**
0.525**
0.465**
−0.311** 1
0.383**
0.386**
0.450**
0.482**
−0.212 1
0.727**
0.634**
0.448**
−0.324 1
0.759**
0.393**
−0.235 1
0.395**
−0.170 1
−0.325** 1
−0.407**
−0.540**
−0.136 −0.367**
−0.539**
−0.046 −0.249
−0.470**
−0.068 −0.393**
−0.244
−0.084 −0.279**
−0.244
0.034 −0.199
−0.293**
−0.064 −0.392** 0.199
−0.482** 0.341**
−0.110
0.005
Sex a NYHA EF
1
0.238
0.166 1
−0.056 1
1
**p < 0.001.
a
Variable dichotomized: 0 = male; 1 = female – point-biserial correlation was used.
Bonferroni correction: new p-value fixed at < 0.005.
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; NYHA: New York Heart Association classification; EF: Ejection fraction.
As shown in Table III, there were moderate positive
correlations between 6MWT and each evaluation in the
MFT. Moreover, the 6MWT was correlated with the
DASI, age, sex and NYHA class (Table III).
Positive correlations were also found between each
evaluation in the MFT and DASI scores. There was
also a very high correlation between the contractions
made by the right and the left arms and the right and the
left legs in the 2 unilateral isometric MFT evaluations.
The results of the MFT lower limb tests were signifi- cantly correlated with age, sex (right leg) and NYHA
classification. The upper limb tests result correlated
with sex (not with the LSF) and NYHA classification
(only with LSF). The DASI score was correlated with
age, sex and NYHA class (Table III). The correlations
among the 6MWT, MFT and DASI scores are shown in
3-D scatter plots for each MFT evaluation (Figs 1–5).
These Figs show that the patterns of correlations were
similar, with no outliers. The only exceptions were the
scores related to the movement-impaired patients with
HF. EF was not significantly correlated with any of the
physical fitness variables.
Regarding movement impairment, Table IV shows
low-to-moderate correlation between impaired limbs
and the respective physical fitness test, except for the
DASI score.
To detect the structure in the relationships among
exercise capacity, muscle function (considering all 5
tests) and functional capacity, a principal component
Fig. 1. 3-D scatter plot of correlations among 6-min walk test (6MWT),
muscle function test (MFT) (right heel-lift) and Duke Activity Status
Index (DASI), in the presence of right leg impairment. Fig. 2. 3-D scatter plot of correlations among 6-min walk test (6MWT),
muscle function test (MFT) (left heel-lift) and Duke Activity Status Index
(DASI), in the presence of left leg impairment.
pancies were the DASI scores. Twelve (12%) patients
had a score above the median on the DASI, but not
on the 6MWT or MFT. Similarly, 7 patients (8%) had
scores above the median in both the 6MWT and the
MFT, but not on the DASI.
Relationships among exercise capacity, muscle
function, functional capacity and clinical variables
J Rehabil Med 51, 2019