Duruturk et al. conducted a study on asthma
patients. The study subjects were divided into two
groups: the treatment group (receiving a 50% dose
of IMT) for 6 weeks and the control group
(receiving respiratory training only). A significant
reduction in the FSS score was only demonstrated in
the treatment group (p = 0.028). Positive impacts
were also seen in respiratory muscle strength,
exercise capacity and quality of life in asthma
patients. Increased respiratory muscle strength is
believed to have a dyspnea-reducing-effect during
training due to the reduced need for required
oxygen. The reduction of required respiratory effort
leads to the reduction of required energy thereby
reducing the severity of fatigue in a person (Durutur,
2018). The results of our study demonstrated that
respiratory training using IS significantly reduced
the severity of fatigue in individuals with SCI after
four weeks of intervention. Respiratory muscles are
vital and play an important role in performing
training. Having strong, long-lasting respiratory
muscles may increase exercise capacity because they
improve lung function, delay fatigue in respiratory
muscles, and increase blood flow to respiratory
muscle tissues as well as other peripheral muscles.
The association between respiratory muscle function
and fatigue had been investigated by Ray et al. They
investigated the association between respiratory
muscle function and fatigue in 37 multiple sclerosis
patients with mild to moderate disability (still able to
ambulate). There was a negative correlation between
respiratory muscle strength (MIP and MEP) and
fatigue perception using Modified Fatigue Impact
Scale (MFIS) questionnaire (Ray, 2015).
Following the CK value in this study, a
significant statistical increase occurred in this study
after 2 weeks intervention (table 3) and became not
significant statistical increase of CK value after 4
weeks intervention (table 4). This is following the
literature stating that increased CK value usually
happens in the initial weeks of exercise indicating
that the initial exercise intensity is given exceeds
muscle capability. This is based on the exercise
principle that in order to give a strengthening effect,
overload exercise intensity should be given. After 4
weeks intervention, CK value increase occurred
insignificantly. This indicates that there has been
muscle adaptation towards the exercise. Several
works of literature mentioned that muscle adaptation
can occur in the third week of the exercise, depends
on the exercise intensity and muscle condition (Ray,
2015; Magal, 2010).
Research on the effect of exercise on CK value
in blood of SCI patient has been done by Robergs et
al., in 1993. They conducted research on CK and
endothelin level of SCI patient (level C7-L1)
through bicycle exercise added by Functional
Electrical Stimulation (FES). The exercise was done
three a week by comparing the CK enzyme and
endothelin level before the exercise, the first week,
the third week, the sixth week and the twelfth week
of the exercise. There was a significant increase of
CK level each week, however, since the third week
on, the increase of CK was not as much as the first
week. This indicated that muscle adaptation started
in the third week of exercise.
Barroso et al performed research on the effect of
regular elbow flexor eccentric exercise. One of the
markers used was the CK examination. The result of
the research indicated that there was a significant
increase in CK value in the first week, while in the
fourth and sixth week, the increase was less. This is
called a repeated-bout effect mechanism which is the
effect of muscle adaptation towards the exercise.
The repeated-bout effect has a protective effect on
the muscle, thus during such condition, muscle
damage will not happen, or even it happened, the
effect will be minimal. Repeated-bout effect
involved a combination of neural, mechanical and
adaptation of cellular. Barroso et al concluded that
there was protection effect towards the effect of
myofibril structure so that it will prevent the
occurrence of muscle damage in the fourth week
(Barroso, 2010). Research conducted by Chen et al
indicated that there was significant muscle damage
for the first two weeks of elbow eccentric exercise,
and it started to decrease in the third week. After the
fourth week of the exercise, the effect of muscle
damage became insignificant. This can be explained
by the occurrence of neural adaptation in the form of
motor unit recruitment efficiency, firing
synchronization increase from the motor unit and the
increase of low type muscle fiber ratio (Chen, 2009).
The limitation of this study did not assess several
factors that may influence the level of fatigue such
as pain, sleep problem, nutrition, the effort of
coping, activity level and spasticity severity.
5 CONCLUSIONS
Four-week respiratory training with IS was effective
at reducing the severity of fatigue in individuals with
SCI. This study also obtained results that there was
no significant increase in the value of CK after 4
week intervention which indicates that the muscles
have adapted to exercise so that there is no longer
any effect of muscle damage due to exercise. Thus,