Scand J Med Sci Sports 1996: 6: 112-121
Copyright 0 Munksgaard 1996
Printed in Denmark .All rights reserved
Scandinavian Journal of
M E D I C I N E & SCIENCE
IN SPORTS
ISSN 0905-7188
Muscular. performance
after
.
. a 3 month .
progressive physical exercise program and
9 month follow-up in subjects with low back
pain. A controlled study
~
4
4
Kuukkanen T, Malkia E. Muscular performance after a 3 month progressive
physical exercise program and 9 month follow-up in subjects with low back
pain. A controlled study.
Scand J Med Sci Sports 1996: 6: 112-121.0 Munksgaard, 1996
The purpose of this study was to assess, in subjects with low back
pain, the changes and their permanence in muscular performance after
a 3 month progressive physical exercise program. Ninety subjects
with chronic low back pain participated in the study. The study
design was controlled and it was carried out in three groups: intensive
training, home exercise, and control group. Isometric and dynamic
muscle strength of the trunk and lower limb were measured, at the
beginning of the study and after the 3 months exercise program, and
then during each of the follow-up sessions. The Oswestry Index and
back pain intensity were also determined. Both exercise groups
received benefit from the progressive exercise program. Their muscular performance improved and their back pain intensity decreased significantly. Among the home exercise group, the Oswestry Index also
changed positively. The results demonstrate that the home exercise
program could be as effective as the intensive training program in
increasing muscle strength, as well as decreasing back pain and functional disability among low back pain patients with mild functional
limitations.
Physiotherapy, consisting mainly of exercise, has
been recommended to subjects with low back pain
as a part of multidisciplinary treatment programs in
combination with other physical modalities. This
has been for the prevention of impairments, for decreasing pain, increasing function and preventing
disability. The specific goals of exercise are most
often, for example, to gain strength, endurance and
flexibility, body control and awareness, to restore
activities of daily living and/or activities at work,
and to give support to other psychosocial rehabilitation regimens (1-4). The physical loads and movements used in different programs have varied from
simple light trunk flexion exercises, developed in
the early 1930s by Williams ( 5 ) , or extension ( 6 ) ,
which have been performed as home programs or
112
T. Kuukkanen’, E. Malkia2
’Central Finland College of Health, Jyvaskyla,
Finland, ‘Department of Health Sciences,
University of Jyvaskyla, Jyvaskyla, Finland
Key words: back pain; muscle strength; muscular
performance; physical exercise
Tiina Kuukkanen, Central Finland College of
Health, Keskussairaalantie 21, 40620 Jyvaskyla,
Finland
Accepted for publication November 24, 1995
gymnasium-like exercises. Later, the home and gym
program exercises have also consisted of various
whole body and limb multiaxial movements (1,7).
These programs were performed, for example, from
only a few minutes of irregular or regular exercise
sessions every second day, up to 40-50 hours per
week. Work-related movements (8) including more
or less educational (9) or behavioral control (2),
were also included as a part of the programs. Many
programs lack a detailed description of the intensity
and the specific movements utilized. The association between physical performance and pain or disability is outlined only in some studies.
There have been some disappointing results in the
literature for simple exercise-type movements in
acute low back pain (10). Some studies have given
Muscular performance
promising results for graded activities as a tool for
effective and economic rehabilitation in chronic low
back pain (2,7,11). There has been a comparison between programs carried out in rehabilitation centers
or in ambulatory practice. Hiirkapaa et a]. (12) have
shown the benefit of inpatient programs, but there is
still an open question as to the proper dose-effect
for outpatients. Could the outpatient programs be
modified so that the dose-effect is equal or even
better than in inpatient programs?
The effect of intensive muscular exercise for
healthy subjects is quite well known. The neuromuscular performance gain with intensive exercises
is reached after about 6-8 weeks regular training
due to neuromuscular adaptation. After this period
hypertrophic muscular changes account for most of
the gains in muscle strength (13). After 3 months of
exercise there is the possibility of neuromuscular fatique, if the intensity of training continues at the
same level (14). Muscular performance explains a
portion of physical ability, for example, opposite to
functional limitations (15). The therapist’s role is vital for the prescription, guidance and measurement
of the contents and the outcomes of exercise programs. A prescribed program should give the best
possible cost-benefit relationship according to the
set goals. The best evidence of the benefit of exercise in prevention of disability is seen with subjects
developing chronic low back pain (2,16).
This study is a part of larger study ‘Active rehabilitation of subjects with low back pain’, with the
main aim being the development of entry and follow-up criteria, as well as the development of measures and programs for the active rehabilitation of
low back patients in physiotherapy. The purpose of
this present study was to determine the effects of
different active and nonactive physical rehabilitation methods on isometric and dynamic muscle
strength, to measure the permanence of changes in
muscular performance after an active 3-month exercise rehabilitation program, and to measure the association of muscular performance with the back
pain intensity and functional disability. This study
should especially help physiotherapeutic outpatient
programs in planning the patient selection criteria,
the content, the outcomes and in realizing the feasibility of the activity based programs.
Material and methods
Subjects
The subjects selected for this study were 90
employed Jyvaskyla Finland residents who had nonspecific, subacute low back pain. The mean age of
the subjects was 39.9k7.9 years. All subjects with a
history of surgery or sciatica were excluded. For the
majority of subjects, the duration of the present episode of low back pain at the time of initial assessment was greater than 3 months (62%). Fourteen
per cent of the subjects had acute low back pain
(duration of 7 days or under). The characteristics of
the subjects are presented in Table 1.
After careful standard medical examinations and
physiotherapeutic screening, and then after the first
measurements had been performed, the subjects
were divided into three groups. The purpose was to
randomize the subjects into the different study
Table 1. Subject characteristics
Sex
Male
Female
Height (crnkSD)
Weight (kg+SD)
First onset of LBP
(years)
Duration of symptoms
27 weeks
27 weeks-6 months
>6 months
Pain intensity
(Berg)
Intensive training
group
Home exercise
group
Control
group
11
18
167k7.3
73+15
15
14
171+11.3
75k15
13
15
168k9.0
72k12
9.7+8.9
11.1k8.8
1O.Ok7.7
ns
33%
33%
34%
22 %
22%
56%
25%
25%
50%
ns
2.5k1.3
1.9+1.5
1.8k1.7
ns
19/1OOk7.8
4.0k1.9
5.1k2.0
18/1OOk9.2
3.9k2.0
5.2+2.1
14/1OOk8.3
4.7k2.5
5.5k1.8
ns
P
ns
ns
ns
Oswestry Index
(%/loo)
Work (MET)
Leisure (MET)
ns
ns
113
Kuukkanen & Malkia
groups. Due to the slow rate of obtaining subject
numbers for this study, randomization was made
more difficult. At the first stage 21 subjects were
randomized into the home (H) and control (C)
groups. Then at the next phase of the study all the
29 subjects were placed into the intensive (I) training group, because their training was required to
commence at the same time. The remaining subjects
were then randomized into the home and control
groups. Further, these 36 subjects entered into the
study in five clusters ranging from 6 to 10 subjects.
These clusters were matched with the intensive
training group according to age, gender and the
level of physical activity at work and during leisure
time. The groups were quite homogeneous and there
were no significant differences between the groups
in their basic characteristics (Table 1).
The duration of the intervention period was 3
months. The post-intervention measurements were
at three (PIl), six (PI2) and twelve (PI3) months
after the baseline measurements (BM). The research
schema is illustrated in Fig. 1. The study had received the acceptance of The Ethical Committee of
the Central Finland Hospital.
Questionnaire
The subjects completed a structured questionnaire
during the initial assessment phase of the study and
then during each of the three follow-up sessions.
The physical activity at work and during the leisure
time was graded according to frequency and intensity of exercise. From each activity level at work
and in leisure time a corresponding MET value
(metabolic unit=at rest 3.5 m1.kg-l .min-') was calculated. At the initial period of the study there were
separate questions on commuting activity. The
reliability and validity of the method has been
shown to be reasonable (17).
The initial onset of low back symptoms and the
duration of the current low back pain symptoms
were obtained. The intensity of the symptoms was
evaluated with the Borg scale (0-1 1 =maximal) (18)
INTENSIVE
TRAINNG
n=29
n=2x
TIME INTERVAL i l
+
GROU5=25
"49
HOME
EXERCISF
GROUP
n=25
n=26
n=26
n=24
+
CORTROL
GROUP
n=26
3
3
PI 1
Fig. 1. The research schema.
114
n=23
+
n=27
MEASUREMENTS EM
n=23
li
PI2
6
MONTHS
PI3
during each measurement session (=back pain intensity), and also during the muscle strength tests (=test
pain intensity). For further analyses the results were
classified into three groups: (a) no symptoms (0);
(b) light or moderate symptoms (0.54); and (c) intense or maximal symptoms (5-1 1).
The degree of functional impairment was assessed (%/loo) with the Oswestry Low Back Pain
Disability Questionnaire (19).
Measurements
Body height and weight were measured with traditional methods. The maximal isometric trunk extension and flexion were measured in a standing
position with a dynamometer. Similarly, isometric
knee extension, ankle extension and flexion strength
were measured with dynamometers but in a sitting
position. The subjects performed three maximal isometric contractions with a 30 second rest period
between each contraction. The best result was
recorded. The testing technique and the reliability of
these measurements have been previously described
(20-23). The absolute values of isometric trunk
strength were used. The dynamic endurance of
back, abdominal and lower limb muscles were
tested according to the method of Alaranta et al.
(24), with the exception that the subjects were
allowed to perform a maximal amount of repetitions. The isometric endurance of trunk extensors
was assessed with the Sorensen test (25).
The reliability and the reproducibility of these
muscle tests have been reported to be sufficient (24).
Three sum indexes of strength were calculated: (a)
index of isometric trunk strength (maximal isometric trunk extension and flexion); (b) index of dynamic endurance of trunk (dynamic endurance of
back and sit-up test); and (c) index of isometric
lower limb strength (isometric knee extension, ankle extension, and ankle flexion).
Physical training program
The aims of the intensive and home training programs were to develop the strength, endurance and
speed of the trunk and lower limb muscles, as well as
to improve the overall body control. Both I and H
groups had first been educated in the ergonomics of
back saving movements at work, and in the importance of leisure time physical activities as a complement or support to therapeutic training. The
progression of the programs was based on tests performed weekly for the intensive and home exercise
groups. According to the results of the tests the load
of each exercise movement was individually
adjusted. Both programs lasted 3 months.
Muscular performance
Intensive training
The program consisted of three different exercise
programs which included seven similar primary exercise movements performed in the gymnasium using
pulleys (Saba), barbells, pillows and plinths. The
tempo, load, duration, speed and repetitions of each
movement were controlled individually. The goal
was to have gym-like exercises performed 3 times/
week, and the home exercises every day. The intensive training group exercised, on average, two times
per week, and they also performed their home exercise programs on average 3.1 times per week.
The total amount of exercise was five times per
week among the intensive training group. There were
10 minute warm-up and cool down periods in both
programs. The strength exercises were performed as
3-4 sets of 7-10 repetitions at 6040% of 10RM (repetition maximum), and the endurance exercises in 3-4
sets of 15-20 repetitions at 3040% of 10 RM. Both
the training and weekly tests were controlled by a
physiotherapist.
Home exercises
The home program also consisted of three different
exercise programs using the same principles used
with the gym-like program. The subjective perceived exertion of the home gymnastics was controlled according to the ratings of perceived exertion
(18). The goal was that all subjects would exercise
once a day and they performed their home program
on average 3.5 times per week. The home program
was checked by a physiotherapist once a month.
Control group
The control (C) group was required to undergo the
same measurements as the intensive and home training groups, but no information or guidance of ergo-
nomics or training was given. The control subjects
were free to follow any treatment protocol if they so
wished.
There was no difference between the three study
groups in the use of physiotherapy services during
the follow-up period. Among all the subjects only a
few subjects were attending ordinary physiotherapy,
and they scattered to different groups.
Statistical analysis
The differences in the test results were tested with
one-way analysis of variance, and with paired ttests. Correlational analyses were also performed.
The statistical analyses were carried out using the
SPSS+ (Statistical Package for Social Sciences)
package.
Results
Muscular performance did not differ between the
three study groups during any measurement session,
except for the dynamic endurance of trunk flexors
where the control group had nearly significantly
(P<0.05) higher values than the intensive or home
exercise group had at the baseline measurement.
There were no statistical differences between males
and females except that men had significantly
(P<O.OOO) higher values for isometric strength tests
during each measurement session.
The muscular performance of the exercise groups
(I & H) similarly increased significantly at every
test occassion (Tables 2-5 and Figs 2 and 3). The
gains in strength increase in the different measurements were from 8% to 80% (Figs 2, 3). There was
no significant change in the muscular performance
of the control group.
The subjects of the intensive training group and
home exercise group were combined because of
Table 2. Maximal isometric trunk extension (N) (meankSD)
Measurement
BM
PI1
PI2
PI3
P
LSD
Intensive training group
(n=22)
6931219.0
780k252.9
823k264.8
8272296.1
0.003
0.001
BM, PI2
BM. PI3
Home exercise group
(n=24)
675k277.5
745k269.4
810k261.6
7792284.6
0.057
0.005
0.031
BM,PII
BM, PI2
BM, PI3
Control group
(n=22)
797k318.5
81 1k273.5
864k269.5
836k262.3
ns
There were no statistical differences between the three study groups during any measurement session
LSD=least significant difference.
115
Kuukkanen & Malkia
Table 3. Maximal isometric trunk flexion
(N) (meankSD)
Measurement
BM
PI1
PI2
PI3
P
LSD
Intensive training group
(n=22)
462k170.2
551k218.6
524k216.9
5101-218.3
0.001
0.008
0.033
BM, PI1
BM, PI2
BM, PI3
Home exercise group
(n=24)
447k174.8
479k157.9
501k181.5
484k183.7
0.026
BM ,PI2
Control group
(n=22)
485k184.6
505k175.3
493k163.0
498k201.9
ns
There were no statistical differences between the three study groups during any measurement session.
LSD=least significant difference.
Table 4. Dynamic endurance of trunk flexors (repetitions) (rneankSD)
Measurement
BM
PI1
PI2
PI3
P
LSD
Intensive training group
(n=20)
22k11.4
34k16.1
29+17.0
30k14.5
0.000
0.002
0.01 2
0.012
BM,PIl
BM,P12
BM,P13
PIl,P12
Home exercise group
(n=24)
28k16.0
4232.5
39k24.2
41k30.5
0.005
0.002
0.006
BM,PII
BM,PI2
BM,P13
Control group
(n=20)
40k25.7
35k21.2
37k26.4
38k25.2
ns
The control group differed statistically (P<0.05) from the intensive training and home exercise groups at the baseline measurement.
LSD=least significant difference.
Table 5. Dynamic endurance of trunk extensors (repetitions) (meankSD)
Measurement
Intensive training group
(n=22)
BM
PI1
PI2
PI3
P
LSD
31k20.0
62k43.0
541-32.3
66k52.5
0.000
BM,PIl
0.000
BM,P12
BM,P13
0.001
Home exercise group
(n=24)
Control group
(n=20)
3213.7
51k41.1
52k32.2
54k38.6
50k22.3
59k36.7
531-39.2
65k43.3
0.000
BM,PII
BM,P12
0.004
BM,P13
0.001
ns
There were no statistical differences between the three study groups during any measurement session
LSD=least significant difference.
their corresponding results. When the subjects of intensive training and home exercise groups were divided into two groups according to their muscular
performance values above (=AA) and below (=BA)
116
the group mean at the baseline measurement, both
groups achieved statistically significant gains in
muscular performance. The only exception was the
isometric lower limb sum index where the better
Muscular performance
rnk endurance
I
..--
BM
PI1
PI2
Measurements
PI3
Fig. 2. The changes (%) in the sum indexes of isometric and dynamic trunk strength and in isometric endurance of trunk extensors. Follow-up values have been analysed by comparison with
the baseline measurements (BM).
.y
- Lowerlimb
isomeliic slrenglh
Knee bend
n
70
40
BM
PI1
PI2
Measurements
PI3
Fig. 3. The changes (%) in the sum index of lower limb isometric strength and dynamic knee bend. Follow-up values have
been analysed by comparison with the baseline measurements
(BM).
group (=AA) could not increase their isometric
lower limb muscle strength during the follow-up
sessions. The results for lower limb strength are presented in Table 6.
The test pain intensity was mostly light or moderate in every measurement session, but the subjects
with intense (>5) symptoms had lower values
(Pc0.05) for isometric and dynamic endurance of
trunk extensors, and for the sit-up test. During the
tests of isometric and dynamic endurance of trunk
extensors, 40% of the subjects were asymptomatic.
Among the symptomatic subjects, the test pain intensity was light ( mean 2.5-2.7). During the tests of
trunk extension and flexion, and the lower limb
measurements, subjects were either asymptomatic,
or the intensity level of the symptoms was low
(means <I .3).
Back pain intensity was light or moderate among
all the subjects and there were no differences between the study groups at the initial (BM) measurement session (Table 7). Back pain intensity was
found to decrease significantly (P<0.015-0.001) for
both of the exercise groups (Table 7). Functional
disability (Oswestry Index) was also low (under
20%), and it decreased significantly (k0.0250.000) for the intensive training and home exercise
groups (Table 8). No correlation was found between
back pain intensity and the Oswestry Index. The
muscle tests did not correlate with back pain intensity, test pain intensity, or with the Oswestry Index.
Those subjects from the intensive and home exercise groups with values below the group mean for
dynamic trunk and lower limb isometric strength at
the baseline measurement achieved significant and
greater decreases during the 3 month exercise period for back pain intensity than those with values
above the mean at the baseline measurement. There
were also significant decreases in the Oswestry Indexes for both of the two groups (above and below
mean values) in every muscular performance variable. Table 6 presents an example of the results with
subjects divided into two groups according to the
mean baseline value of lower limb strength.
Figure 4 presents an example of the results, with
subjects divided into two groups according to the
isometric endurance of the trunk extensors. The significantly higher values of back pain intensity in the
BA group compared to the AA group at the baseline
measurement were not anymore significantly higher
in the post-intervention measurements, as the isometric endurance of trunk extensors was used as the
grouping criteria (Fig. 4). The significant difference
in low back pain intensity between the two subgroups (BA and AA) at the baseline measurement
session disappeared by the first post-intervention
measurement (PIl), and also at the follow-up measurements (PI2,PI3), as dynamic trunk endurance
and lower limb isometric strength were used as the
grouping criteria.
The values of the Oswestry Indexes of the BA
group decreased in parallel with the values of the
AA group without any significant differences at the
baseline and post-intervention measurements, as the
isometric endurance of trunk extensors (Fig. 4), isometric trunk strength and isometric lower limb
strength were used as the grouping criteria. The significantly higher values of the Oswestry Index in the
117
Kuukkanen & Malkia
Table 6. Changes in the sum index of isometric lower limb strength, back pain intensity, and the Oswestry Index in two groups according to the mean value of sum
index of isometric lower limb strength. The intensive and home groups are treated together. AA =the group with values of the sum index of isometric lower limb
strength above the baseline average. BA =the group with values of the sum index of isometric lower limb strength below the baseline average.
Measurement
AA
Sum index of isometric lower limb strength
Criteria 1148.9N
BA
AA n=22
Back pain intensity
BA n=27
LSD
BM
PI1
PI2
PI3
P
1449k171.4
1444k159.2
1489k197.9
1466k212.6
ns
910k144.3
1039K206.1
1032k263.8
1008k235.5
0.000
BM,PIl
0.007
0.008
BM,PIZ
BM,P13
1.8+1.4
2.5k1.4
1.4fl.2
ns
1.4k1.2
1.3k1.2
ns
1.4k1.4
ns
1.3k1.4
ns
1.21.3
0.001
BM,PIl
BM,PIZ
BM,P13
0.001
0.000
19k8.7
AA n=25
14f8.1
10k6.0
8k6.0
0.031
0.000
BM,PIl
BM,PIZ
BM,P13
0.018
0.000
0.026
BM,PIl
BM,PIZ
BM,P13
0.003
Oswestry index
BA n=29
ns
18k8.3
ns
11+7,3
ns
10*8,3
ns
lOk10.0
* =Statistically significant (R0.05) difference between groups AA and BA.
ns=no significant differences between groups AA and BA.
LSD=least significant difference.
Table 7. The differences between measurements of back pain intensity among the study groups (meankSD)
Measurement
Intensive training group
(n=22)
Home exercise group
(n=24)
Control group
(n=20)
BM
PI1
PI2
PI3
P
LSD
2.5k1.3
1.4k1.3
1.7k1.2
1.521.4
0.003
BM,PIl
0.003
0.001
BM,P12
BM,P13
0.013
BM,PI2
0.015
BM,P13
0.033
BM,PIl
1.9k1.5
1.8+1.7
1.3+1.2
1.1k1.3
1.Ok1.3
1.3k1.6
l.Ok1.3
1.3k1.8
There were no statistical differences between the three study groups during any measurement session
LSD=least significant difference.
BA group compared to the AA group at the baseline
measurements were not anymore significantly
higher in the postlintervention measurements, as the
dynamic trunk endurance and knee bend tests were
used as the grouping criteria. This confirms that for
those who have had their values below the mean
(BA group) in muscle tests, and the significant differences between the BA and AA groups in low
back pain and/or Oswestry Index had disappeared
118
by the time of postlintervention tests, there has been
a significant beneficial association between muscular performance effect of exercise and the decrease
of low back pain and/or Oswestry Index.
Background factors, such as age and physical activity at work and during leisure time were controlled. After adjusting for age and physical activity
levels at work and during leisure time, no changes
in the results were observed.
Muscular performance
Table 8. The differences between measurements of the Oswestry Index among the study groups (meankSD)
Measurement
Intensive training group
(n=13)
BM
PI1
PI2
PI3
P
LSD
17k5.8
11k4.4
1Ok6.2
1Ok4.6
0.016
BM,PIl
0.011
BM,PI2
BM,P13
0.007
Home exercise group
(n=17)
17k9.5
Control group
(n=12)
1Ok7.6
14k8.7
11k7.8
8k6.6
12k9.0
6k5.2
10k9.5
0.002
0.000
0.000
0.025
0.003
BM,PIl
0.025
BM,PIl
BM,PIZ
BM,P13
PIl,P12
PIl,P13
There were no statistical differences between the three study groups during any measurement session.
Discussion
The results of this study indicated, as have previous
studies (e.g. 7), that it is possible to significantly
increase muscle strength and endurance of low back
pain subjects during 3 months of progressive exercise. The changes in muscle performance were parallel in both exercise groups (I & H), and the
changes appeared to be more permanent in the home
exercise group. The benefit of home exercise has
not been proved in earlier studies, even though
many textbooks have described exercise programs
suitable for the home (1,4). An effective home exercise program demands continuous and regular control by the subject and also by a physiotherapist, or
by other professionals involved in the rehabilitation
process. The similar results of Reilly et al. (26) also
Low back pain intensity
Osuespy
BM PI1
A
XI
PI2
PI3
BM
PI1
PI2
PI3
=THE GROUP (AA) WITH VALUES OF ISOMETRIC ENDURANCE OF THE TRUNK EXTENSORS
ABOVE THEMEANVALUEATTHEBASELINEMEASUREMENT
iTHE GROUP (BA) VALUES OF ISOMETRIC ENDURANCE OF THE TRUNK EXTENSORS
BELOW THE MEAN VALVE ATTHE BASELINE MEASUREMENT.
=STATISTICALLY SIGNIFICANT DIFFERENCE (p= 002) BETWEEN THE GROUPS AA AND BA
Fig. 4. The changes in the Oswestry Index and low back pain
intensity according to the values of isometric endurance of the
trunk extensors above and below the mean. There were statistically significant decreases in the Oswestry Index and low back
pain intensity in both groups (AA and BA) between baseline
and follow-up measurements.
confirmed the importance of supervision. The intensity and biomechanical quality of the exercises
should also be controlled. The program utilized by
the home exercise group was checked by a physiotherapist only three times during the 3 month training period, and so we may postulate that the costeffectiveness in respect of muscular performance
was the highest for the home exercise program
group in this study.
The positive changes were more pronounced in
the dynamic muscle strength tests, and also in the
isometric endurance of trunk extensors. We suggest
that the primary reason for this was the dynamic nature of the exercise programs. A part of the gain
may be due to the learning effect. The tests of maximal isometric strength using dynamometers could
be more difficult to learn than the dynamic and more
functional movements (or vice versa). Also, the response of the muscles assessed with isometric tests
may not be as effective as those used in the dynamic
tests. The overall assumption of the learning effect
in these repeated measurements was taken into account, but the results of the control group did not
support this explanation.
There were positive and permanent changes in
back pain intensity and the Oswestry Index for both
the exercise groups. The s'ubjects had only experienced light or moderate symptoms during the tests.
The pain during the muscle tests did not have an influence on the test performances. These subjects did
not have a degree of functional limitation which
could have been hindered by the tests, and their
back pain was not at either the acute or very chronic
phase (which causes secondary limitations of function). This was also evident from their very good
values for the muscle tests performed at the initial
119
Kuukkanen & Malkia
baseline measurement session compared with
healthy subjects in other studies (e.g. 24) as well as
the very mild functional disability indicated in the
Oswestry Index.
There were some trends that after the 3 month
follow-up, the muscle performance values began to
decrease. This may mean that the intensive exercise
periods of home or gym exercises should be repeated about 6-9 months after the initial exercise
session. The prescription of exercises may only be
meaningful for those whose muscular values are below the mean reference values of healthy subjects.
Especially useful tests could be the dynamic trunk
tests, isometric endurance of trunk extensors and
lower limb strength tests, because they are associated with pain and functional disability. If the response is not clear for the dynamic and isometric
muscle strength tests after 3 months of exercise,
there is no reason to expect any further benefit from
continued exercise. It seems that those who can
reach the plateau in low back pain intensity (about
1) and in the Oswestry Index (about 10%) could not
obtain benefit from physical exercise anymore in
this respect, even though muscular performance
could still increase in heavier exercises. These assumptions will require further research and investigations. If and when rehabilitative exercise should
be repeated, for those who have had a reasonable response to the initial exercise program, is still an
open question.
In conclusion, positive improvement of muscle
performance was achieved with the 3 month intensive and home exercise, and these changes ranged
from 10% to 80%. Back pain intensity and functional disability also decreased significantly. The decrease of back pain intensity was associated with the
gain in muscular performance, for those whose
muscular performance values were below the average. The permanence of these positive changes was
still present at least 6 months after the intervention.
Ac know Ied g erne nts
We are very grateful for the assistance of Sinikka Kilpikoski
M.Sc, P.T., Jyri Manninen M.Sc, P.T., and Tommi Salmela
M.Sc. as well as the personnel and students at the Department
of Health Sciences, University of Jyvaskyla. This work was
supported by grants from the University of Jyvaskyla, the Ministry of Education, the Juho Vainio Foundation and the TULESGS program.
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