TITLE: The effect of chest expansion exercise with TENS on gait ability and trunk
control in chronic stroke patients

  ABSTRACT:
[Purpose] The purpose of this study was to investigate the effect of chest expansion
exercise with transcutaneous electrical nerve stimulation (TENS) on gait ability and trunk
control of patient with stroke. [Subjects and Methods] The subjects were divided into 7 in
the chest expansion exercise with TENS group (experimental group) and 7 in the chest
expansion exercise with placebo TENS (control group). The gait ability and trunk contol
were measured using Six-Minute Walk Test, Tinetti gait index and Trunk impairment scale
(TIS). [Results] Both the experimental group and the control group showed significant
improvement in the Six-Minute Walk Test, Tinetti gait index, and TIS total score. The
dynamic sitting balance and coordination of TIS showed significant improvement only in the
experimental group. In comparison between the two groups, the experimental group showed a
more significant improvement in Tinetti gait index and TIS total score than the control
group. [Conclusion] This study showed that chest expansion exercise with TENS was an
effective method for improving gait ability and trunk control in chronic stroke
patients.

BODY.INTRODUCTION:
Following stroke, patients with hemiplegia show weakness in their trunk muscles1, 2).
Consequently, it is necessary to develop an intervention method that can selectively
activate these muscles and improve their ability to regulate the body and gait ability.  Transcutaneous electrical nerve stimulation (TENS) provides sensory cues by stimulating
below the threshold of motor nerves3, 4). The activity of respiratory muscles is
significantly correlated with trunk control5), and the performance ability of the trunk is closely related to
gait6).  The intervention involved in the present study is characterized by the combination and
application of TENS with the one-sided chest expansion exercise.  The purpose of this study was to identify an effective interventional method for the
rehabilitation of stroke patients by identifying the effects of TENS on trunk control and
gait ability in stroke patients when applied simultaneously with chest expansion
exercise.

BODY.SUBJECTS AND METHODS:
This study involved 14 stroke in-patients at A Hospital. The inclusion criteria were as
follows: diagnosed with stroke 6 months ago, no congenital deformity in the chest, a score
of 24 points in the Korean Mini-Mental State Examination (K-MMSE), no serious abnormality in
the pin prick test, ability to walk 20 m independently without aids, ability to hold a
standing posture for 30 seconds or more, and the absence of skin disease. Before starting
the study, we explained the purpose, process, and risk factors of this study, and obtained
written consent from each participant. The general characteristics of the experimental group
were as follows: age, 62.00 ± 10.36 years; weight, 72.00 ± 5.20 kg; time since stroke, 11.86
± 3.02 months; K-MMSE, 26.14 ± 1.21; gender, 6 male and 1 female, The general
characteristics of the control group were: age, 66.71 ± 5.02 years; weight, 69.71 ± 7.78 kg;
time since stroke, 12.43 ± 2.99 months; K-MMSE, 26.29 ± 1.25; gender: 5 male and 2 female.
This study was conducted according to the Declaration of Helsinki and was approved by the
Institutional Review Board of Yongin University.  The Trunk Impairment Scale (Korean version) was used to evaluate trunk balance and
coordination ability in a sitting posture. The higher the score, the better the trunk
balance and coordination ability.  The Tinetti-Gait Scale (Korean version) was used to evaluate gait ability.  The six-minute walk test was performed to evaluate gait endurance. This evaluation was
carried out by marking a 20-meter-long footpath on the floor and asking the participants to
walk on it repeatedly for 6 minutes. The distance (m) in which the participants moved for 6
minutes was recorded and used as a data point.  All participants performed 30 minutes of general exercise therapy, including mat exercise
and gait exercise. The intervention period was 4 weeks, 5 times a week. For the chest
expansion exercise, 3–5 ribs or 7–9 ribs on the non-paretic side were manually contacted and
a quick stretch was applied at the end of the exhalation. When the chest became swollen on
the non-paretic side during inhalation, resistance in the opposite direction was provided by
the therapist's hand7).  For certain parts of this study, TENS (Novastim CU-FS1, CU Medical Systems, Korea) was
applied. TENS (frequency: 0–100 Hz; pulse width: 20–700 μs) provided a stimulus that the
participants could easily feel, and the level of stimulation was increased until just prior
to muscle contraction. To each participant, a pair of electrodes was attached to the
latissimus dorsi muscle and the external oblique muscle4). The intervention time was 30 min and TENS was applied
simultaneously with the chest expansion exercise.  Statistical analysis and treatment were performed using SPSS 20.0 (Windows version).
Differences between the experimental and control groups were analyzed with the Mann-Whitney
U test. Wilcoxon's signed-ranks test was also used to compare differences in variations
between the two groups. Tests were considered to be statistically significant when
p<0.05.

BODY.RESULTS:
Both the experimental group and the control group showed a significant improvement in
six-minute walk test, Tinetti Gait Index, and TIS Total score (p<0.05), but only the
experimental group showed a significant improvement in dynamic sitting balance and
coordination among the TIS subscales (p<0.05). When comparing effects between the two
groups, the experimental group showed more significant improvement than the control group in
both the Tinetti Gait Index and the TIS Total Score (p<0.01) (Table 1Table 1.Changes of outcome measurements on two intervention groupsCategoriesExperimental group(n=7)Control group(n=7)Six-Minute Walk Test (meter)Before142.6 ± 50.4132.0 ± 66.1After159.0 ± 55.4*149.9 ± 66.6*Tinetti gait index (point)Before5.7 ± 1.65.2 ± 2.0After8.1 ± 1.5*‡6.1 ± 2.1*Trunk impairment scale total scoreBefore9.7 ± 2.611.4 ± 3.4After14.0 ± 2.8*‡13.1 ± 3.5*Static siting balance scoreBefore5.5 ± 0.95.4 ± 1.2After6.4 ± 0.55.8 ± 0.9Dynamic siting balance scoreBefore2.8 ± 2.14.0 ± 2.3After4.7 ± 2.4*4.86 ± 2.5Coordination scoreBefore1.2 ± 0.72.0 ± 0.0After2.8 ± 0.9*2.4 ± 0.5Valures are means ± SD. *Significant difference between before and after the chest expansion exercise in each
group (p<0.05). ‡Significant difference between the experimental group and control group
(p<0.05).).

BODY.DISCUSSION:
Data showed that the experimental group and the control group showed significant
improvement in TIS, Tinetti Gait Index, and the six-minute walk test after intervention.
However, only the experimental group showed significant improvement in dynamic sitting
balance, coordination among the TIS subscales, and a more significant increase in the
Tinetti Gait Index and TIS total score, as compared to the control group.  TENS attached to the external oblique muscle and the latissimus dorsi muscle, the
latissimus dorsi muscle showed more significant improvement in TIS than placebo TENS did in
task-related trunk training4).  The six-minute walk test, which was used to test gait endurance in this study, is known to
be more affected by ankle or leg function than by cardiovascular loads or aerobic
thresholds8). Therefore, gait training
among general exercise treatment programs, which was applied equally to both groups,
influenced the six-minute walk test result in stroke patients; consequently, there was no
significant difference between the two groups with this respect.  A previous study of stroke patients showed that a reduction in trunk control ability and
Tinetti Gait Index was related to the total TIS score of each specific item6). Therefore, our present experimental group
showed a significant increase in dynamic sitting balance score and coordination score of the
TIS, and thus demonstrated better results in the Tinetti-Gait Score and TIS total score than
the control group.  The chest expansion exercise used in the present study is an intervention method used to
help chest movement and contraction of the diaphragm9). It is considered that an increase in chest mediolateral and
anterioposterior diameters, inspiratory muscle contraction10) causes a subsequent increase in intra-abdominal pressure, which is
effective in improving trunk stability and gait ability. The application of TENS in the
present study helped the paretic sensory input to stimulate the paretic trunk muscles,
thereby further increasing trunk control3).  This study is of significance in that it not only confirmed improvement in trunk control
after TENS intervention but also identified gait ability as a factor to consider for trunk
stability.  However, there are some limitations associated with the present study that should be
considered when interpreting our results. First, the study only involved a small number of
subjects. Second, evaluation items were judged by the therapist or just checked the time and
distance. In future studies, it is expected that there will be more a meaningful difference
if evaluations are applied to a greater number of participants by using additional tests
that can quantitatively identify a wider range of temporal and spatial variables associated
gait and trunk stability.

BODY.CONFLICT OF INTEREST:
None.

Question: Compared to 7 in the chest expansion exercise with placebo TENS (control group) what was the result of 7 in the chest expansion exercise with transcutaneous electrical nerve stimulation (TENS) group (experimental group) on dynamic sitting balance and coordination?
Evidence: Both the experimental group and the control group showed a significant improvement in
six-minute walk test, Tinetti Gait Index, and TIS Total score (p<0.05), but only the
experimental group showed a significant improvement in dynamic sitting balance and
coordination among the TIS subscales (p<0.05). 
Answer: significantly increased