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Accepted Manuscript
Variations during repeated standing phases of asymptomatic subjects and lowback pain patients
Hendrik Schmidt, Maxim Bashkuev, Jeronimo Weerts, Friedmar Graichen,Joern Altenscheidt, Christoph Maier, Sandra Reitmaier
PII: S0021-9290(17)30313-5DOI: http://dx.doi.org/10.1016/j.jbiomech.2017.06.016Reference: BM 8255
To appear in: Journal of Biomechanics
Received Date: 5 January 2017Revised Date: 9 May 2017Accepted Date: 13 June 2017
Please cite this article as: H. Schmidt, M. Bashkuev, J. Weerts, F. Graichen, J. Altenscheidt, C. Maier, S. Reitmaier,Variations during repeated standing phases of asymptomatic subjects and low back pain patients, Journal ofBiomechanics (2017), doi: http://dx.doi.org/10.1016/j.jbiomech.2017.06.016
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customerswe are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, andreview of the resulting proof before it is published in its final form. Please note that during the production processerrors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
1st revision (Ms. No. BM-D-17-00012)
How do we stand?
Variations during repeated standing phases of asymptomatic subjects and low back pain
patients
Hendrik Schmidt1, Maxim Bashkuev1, Jeronimo Weerts1, Friedmar Graichen1, Joern
Altenscheidt2, Christoph Maier2, Sandra Reitmaier1
1 Julius Wolff Institut, Charité – Universitätsmedizin Berlin, Germany
2 Department of Pain Management, BG-University Hospital Bergmannsheil, Bochum, Germany
Address of corresponding author
Hendrik Schmidt
Julius Wolff Institut
Charité – Universitätsmedizin Berlin
Augustenburger Platz 1
13353 Berlin
Germany
Phone: +49 30 2093 46016
Fax: +49 2093 46001
Email: [email protected]
Word count:
Abstract: 210
Introduction - Discussion: 3540
2
Abstract
An irreproducible standing posture can lead to mis-interpretation of radiological measurements, wrong
diagnoses and possibly unnecessary treatment. This study aimed to evaluate the differences in lumbar
lordosis and sacrum orientation in six repetitive upright standing postures of 353 asymptomatic subjects
(including 332 non-athletes and 21 athletes – soccer players) and 83 low back pain (LBP) patients using a
non-invasive back-shape measurement device.
In the standing position, all investigated cohorts displayed a large inter-subject variability in sacrum
orientation (~40°) and lumbar lordosis (~53°). In the asymptomatic cohort (non-athletes), 51% of the
subjects showed variations in lumbar lordosis of 10–20% in six repeated standing phases and 29%
showed variations of even more than 20%. In the sacrum orientation, 53% of all asymptomatic subjects
revealed variations of >20% and 31% of even more than 30%.
It can be concluded that standing is highly individual and poorly reproducible. The reproducibility was
independent of age, gender, body height and weight. LBP patients and athletes showed a similar
variability as the asymptomatic cohort. The number of standing phases performed showed no positive
effect on the reproducibility. Therefore, the variability in standing is not predictable but random, and
thus does not reflect an individual specific behavioral pattern which can be reduced, for example, by
repeated standing phases.
Keywords
Human Posture; Standing; Lumbar Lordosis; Sacrum Orientation; Age; Gender
3
Introduction
The degree and progression of spinal disorders is frequently evaluated in full-length sagittal-plane
radiographs of the spine and pelvis in an upright standing position. For standardized capture of the
current state of alignment (Amonoo-Kuofi, 1992; Hammerberg and Wood, 2003) and for a more precise
assignment of patients to appropriate treatments (Lin et al., 1992; Tuzun et al., 1999), different
anatomical parameters have been identified: e.g., pelvic incidence, pelvic tilt (Hansson et al., 1985;
Schwab et al., 2006), vertical plumb line (Gelb et al., 1995; Jackson and McManus, 1994; La Grone, 1988),
lumbar lordosis (Pellet et al., 2011; Troke et al., 2005; Van Herp et al., 2000) and sacrum orientation
(Peleg et al., 2007a; Peleg et al., 2007b). During radiographic examination, patients are requested to
stand relaxed with extended knees and parallel shoulder girdle and pelvis (Stagnara et al., 1982). Despite
these instructions, variations in the adopted posture cannot be avoided. Just a slight pelvic rotation
combined with hip extension was found to markedly shift the anterior-superior corner of the sacrum,
causing a change in the horizontal distance of the plumb line to the S1 vertebra (Gelb et al., 1995;
Jackson and McManus, 1994).
To provide adequate visualization of the spine, the typical diagnostic lateral radiograph is often taken
with the subject’s arm flexed forward (Gelb et al., 1995; Vedantam et al., 1998). The effect of different
arm positions on the segmental and global changes in the sagittal alignment of the spine associated with
two standing radiographic positions (arms forward-flexed to 45° vs. fists-on-clavicles) was examined in
asymptomatic subjects (Aota et al., 2009) and in patients with adolescent idiopathic scoliosis (Faro et al.,
2004). It was attempted to define the most functional standing position for the evaluation of an accurate
sagittal balance. Aota and colleagues (2009) showed that fists-on-clavicles caused less negative shift in
plumb line and less compensatory posterior rotation of the pelvis, and therefore appeared more
appropriate for defining a patient’s functional balance. However, in patients with a previous spinal
fusion, Vedantam et al. (1998) recommended positioning the arms at 30° for a lateral radiograph to
prevent a negative shift in the plumb line and to gain a more functional position.
4
Currently, it has not been investigated how sagittal alignment parameters can change under repetitive
upright standing positions. Therefore, the reproducibility of lumbar lordosis and sacrum orientation
among six repetitive upright standing postures of 353 asymptomatic subjects (including 332 non-athletes
and 21 athletes) and 83 low back pain (LBP) patients was evaluated. We postulated the following
hypotheses:
1. The variability in lumbar lordosis and sacrum orientation in repetitive upright standing postures
decreases with the number of standing phases. After an initial adaptation-phase it was expected that
subjects will get more and more familiar with the test set-up and, therefore, the variability will
decrease in repeated standing phases.
2. Age and gender significantly affect the variation in lumbar lordosis and sacrum orientation. Own
previous findings indicated a significant correlation between gender/age and lumbar lordosis/sacrum
orientation (Dreischarf et al., 2014; Pries et al., 2015a).
3. LBP patients show a significantly greater variability in lumbar lordosis and sacrum orientation than
asymptomatic subjects due to pain-related functional adaptation and/ or pain and movement
avoidance behaviour.
4. Athletes with a higher and more uniform fitness level stand more reproducible than non-athletes. The
authors assumed that neuromotoric and muscular adaptations support athletes to have a more stable
and reproducible posture in comparison to the general population and especially to patients.
5
Methods
Ethics
The Ethics Committee of the Charité – Universitätsmedizin Berlin for asymptomatic subjects (registry
numbers: EA4/011/10, EA1/162/13) and the Ruhr University Bochum for LBP patients (registry numbers:
4385-2012 (06.07.2012); 4427-12 (20.08.2012); 5233-15 (26.03.2015)) approved this study. All
participants were informed about the study’s procedure and signed a written consent giving their
permission to conduct measurements.
Asymptomatic subjects – non-athletes
This group includes data from 332 subjects (187 females; 145 males) from a previously published cohort
on the measurement of lumbar spinal posture and motion (Consmuller et al., 2012a). These subjects did
not experience pain in the lower back or pelvis in the 6 months prior to the measurements and never
underwent spinal or pelvic surgery. More details are provided in Table 1.
Athletes - Soccer players
This group includes data obtained from 21 men without pain in the lower back or pelvis in the 6 months
prior to the measurements and who had no history of spinal or pelvic surgery. They were recruited from
a professional soccer team and regularly performed seven training sessions á 90 min per day
(10.5 h/week).
LBP patients
This group includes data from 83 patients with chronic LBP of >12 months duration (range: >12 month to
>20 years). Patients with paresis, for example, after nerve-root compression, other acute serious
conditions (e.g., tumor, infection, compression fracture, heart insufficiency) and prior fusion surgery of
more than two segments were excluded.
6
Measurement system
The Epionics SPINE system (Epionics Medical GmbH, Potsdam, Germany) was used to assess lumbar
spinal shape as well as sacrum orientation and rotation in the sagittal plane (Fig. 1). The system involves
two flexible sensor strips, each consisting of twelve 2.5-cm-long segments based on differential strain-
gauge elements which provide a sensitive measure of the curvature in each segment. During a
measurement, the sensor strips are inserted into two hollow plasters attached to the back
paravertebrally, 7.5 cm away from the spinal column on each side.
The lower end of each strip was aligned with the spina iliaca posterior superior, which was approximately
in line with the first sacral vertebra. A tri-axial accelerometer was located at this end, allowing the
system to assess sacrum orientation. This acceleration sensor determined the spatial orientation of the
sensor relative to the vertical direction of the earth’s gravitational field. The sensor strips were
connected to a storage unit (size: 12.5 cm × 5.5 cm; mass: 80 g) that collected data with a frequency of
50 Hz. The sensor strips of the system exhibit high accuracy and repeatability (interclass correlation
coefficient, ICC>0.98) with test-retest reliability ICCs of >0.98. Previous studies confirmed the suitability
of the system for assessing lumbar and pelvic motion (Consmuller et al., 2012a, b; Pries et al., 2015b;
Rohlmann et al., 2014; Taylor et al., 2010).
Measurement protocol
All study participants were equipped with the Epionics SPINE system and performed a standardized
choreography consisting of (1st standing) flexion, (2nt
standing) extension, (3rd standing) left and (4th
standing) right
lateral bending as well as (5th
standing) left and (6th
standing) right axial rotation (Fig. 1). Each exercise was
repeated three times before going to the next exercise. Before each exercise, the subjects were explicitly
requested to stand in a relaxed upright position with extended knees for 2 seconds. In these 2 seconds,
the lumbar lordosis and sacrum orientation were recorded in a frequency of 50 Hz and subsequently the
mean value of both was calculated.
7
Data analysis
The lumbar angle was individually calculated by summing all Epionics’ segments that were lordotically
curved in the individual volunteer, as shown by the transition from lordosis to kyphosis (change of sign)
during standing, accounting for differences in subjects’ anthropometrics. The corresponding data from
the left and right sensors were averaged. Sacrum orientation was determined from the orientation of the
accelerometer (Pries et al., 2015a). All data were processed using in-house developed MATLAB routines
(MATLAB R2009b, MathWorks, Inc., Natick, MA, US.).
Statistics
The Kolmogorov-Smirnov-Lilliefors test was applied to evaluate the normal distribution for each
investigated group. To detect the presence of outliers, the Grubb’s test was performed. Levene’s test
was used to test for variance homogeneity. For normally distributed data and variance homogeneity,
Student’s t-test was applied to access gender-specific differences and a one-way analysis of variance
(ANOVA) followed by post hoc Scheffé’s test to analyze differences between cohorts. The subjects were
later grouped based on the variability in the sacrum orientation and lumbar lordosis during different
standing phases. Due to small size of the individual sub-groups, the non-parametric Friedman test was
performed to assess the differences between repeated measurements in the subgroups, followed by
post hoc Nemenyi test. Additionally, a regression analyses was applied and the coefficient of
determination (R2) was calculated. P-values of <0.05 were considered statistically significant. The
statistical analyzes were performed with R 3.2.5 (R-Core-Team, 2016).
8
Results
In the standing position, all investigated cohorts displayed a large inter-subject variability in sacrum
orientation and lumbar lordosis (Fig. 2). As an example, for asymptomatic subjects, the sacrum
orientation ranged between 1.2° and 38.5° while the lumbar lordosis varied between 7.7° and 59.5°. The
lumbar lordosis in LBP patients did not differ significantly from asymptomatic subjects (p = 0.29);
however, the sacrum orientation was significantly smaller (11.6°, p < 0.001). Moreover, both lumbar
lordosis and sacrum orientation significantly differed between asymptomatic subjects and soccer
players. While the lumbar lordosis of soccer players was larger (39.1°; range: 21.7–59.5°; p < 0.001), the
sacrum orientation was smaller (13.3°; range: 1.9–26.8°; p = 0.003). A significant difference was detected
between LBP patients and soccer players in lumbar lordosis (30.1° vs. 39.1°, p < 0.001), but not in sacrum
orientation (11.6° vs. 13.3°, p = 0.51). After adjusting the data for age and gender, the difference in the
lumbar lordosis remained significant only between asymptomatic subjects and soccer players (p = 0.034).
The sacrum orientation in asymptomatic subjects was still significantly different from both soccer players
(p = 0.002) and LBP patients (p = 0.017).
In six repeated standing phases, 51% of all asymptomatic women and men showed on average variations
in lumbar lordosis between 10% and 20%; 20% between 20% and 30% and 6% between 30% and 40%
(Figs. 3, 4). In the sacrum orientation, 42% of all asymptomatic women and 29% of all asymptomatic men
revealed variations of 10%-20%. Interestingly, 18% of all asymptomatic men showed variations in sacrum
orientation >40%. For variations of 10–20%, sacrum orientation and lumbar lordosis did not show
significant differences between repeated measurements (① and ② in Fig. 3; p=0.34). For variabilities
>50%, the variations in sacrum orientation decreased significantly with the number of repetitions (③ in
Fig. 3, p=0.003 between the first and the last standing phases). Similarly, high variability in the lordosis
demonstrated no significant changes between the repeated measurements (④ in Fig. 3; p=0.34)
9
The percentages of subjects of different variability levels did not substantially change between men and
women or between asymptomatic subjects and LBP patients (Fig. 4). However, soccer players displayed a
more uniform distribution in sacrum orientation and lumbar lordosis, with up to 40% variability.
In the absolute values, the majority of study participants showed variations of 2–10° (Fig. 5). However,
2% of the asymptomatic subjects, 5% of LBP patients and 10% of the soccer players displayed variations
of >12°, mostly in sacrum orientation. Maximum values of 16.3° in sacrum orientation and 19.9° in
lumbar lordosis were found for asymptomatic subjects, 13.8° and 23.8°, respectively, for LBP patients
and 10.6° and 14.4°, respectively, for soccer players.
Body height, body weight and age displayed no effect on the variability in sacrum orientation and lumbar
lordosis (R2<0.033; Fig. 6). Similar trends could be observed for LBP patients and soccer players (R2<0.04)
as well as separately for gender sub-cohorts (R2<0.04). Moreover, the time of the day showed also no
effect on the variability of both parameters in all three cohorts (R2<0.012).
10
Discussion
An irreproducible standing posture can lead to false radiological measurements, incorrect diagnoses and
possibly unnecessary treatment. For X-ray examination, physicians usually instruct the patient to stand in
a relaxed position, as this is assumed to be the most reproducible posture and allows the best possible
overview of the spinal shape. Furthermore, standing often forms the basis (as an anatomical reference
frame) for motion analyzes in laboratory setup. However, numerous relaxed positions are possible, and
thus inconsistent postures may be taken. Therefore, it is difficult to ensure a reproducible state in this
posture. This work, exploiting data collected in earlier studies, was designed to evaluate the variations in
sacrum orientation and lumbar lordosis in six repetitive upright standing postures of different cohorts:
332 asymptomatic non-athletes (general population), 21 asymptomatic soccer players and 83 LBP
patients. It was demonstrated that sacrum orientation and lumbar lordosis in the standing position are
highly variable (individual). For asymptomatic non-athletes, the lordosis angle varied between 7.7° and
59.5° and the sacrum orientation between 1.2° and 38.5°. Previous studies have also indicated a large
degree of normal variability in the sagittal alignment of the spine in young, healthy subjects (Stagnara et
al., 1982), middle- and older-aged patients (Gelb et al., 1995) and patients with back pain (Jackson and
McManus, 1994; Kumar et al., 2001). It is therefore unreasonable to expect one “normal lordosis” or
“normal sacrum orientation” of subjects/patients in the standing position.
The results further demonstrated a high variability in lumbar lordosis and sacrum orientation between
six repeated standing phases. In the sacrum orientation, for example, 53% of all asymptomatic subjects
displayed variations of >20%, 31% of >30% and 18% of >40%. In absolute values, 2% of the asymptomatic
subjects, 5% of the LBP patients and 10% of the soccer players showed variations of >12°. Maximum
variations of 16.3° in the sacrum orientation for asymptomatic subjects and 23.8° for LBP patients were
found. Several studies have indicated that the sagittal alignment can be accurately measured and that
the measurements were repeatable when the same subject was examined at two different points in time
11
(Jackson and Hales, 2000; Jackson et al., 1998). This cannot be supported by the present findings. At this
point it should be mentioned that the measurement device was fixed at the subject’s back once and not
removed and reattached during the measuring session. This prevents additional measurement
inaccuracies (variations in lumbar lordosis and sacrum orientations between different standing phases)
due to an imprecise reattachment of the device.
Contrary to our first hypothesis, the variability in lumbar lordosis and sacrum orientation did not
decrease with the number of standing phases. The authors hypothesized that the greatest variations in
lumbar lordosis and sacrum orientation occur between the first and second standing phase. They
assumed that the first measurement provokes the subjects to think too much about what they are
requested to do and thus take an unusual posture. After the first flexibility measurement (three times
flexion), the subject should be standing more relaxed, and therefore, the variability should diminish with
increased standing phases, which was, however, not supported by the results.
Contrary to our second hypothesis, no influence of gender and age on the variability in standing was
found. LBP patients did not show a greater variability of different standing postures, which disagrees
with our third hypothesis. Therefore, it is important to understand that the variability in standing is not
predictable but random, and thus does not reflect an individual specific behavioral pattern which can be
reduced, for example, by repeated standing phases.
The fourth hypothesis that regularly trained subjects improve the reproducibility of standing postures
was also not supported by the present findings. The authors assumed that their muscular adaptations
support them to have a more stable and therefore a more reproducible posture in comparison to the
general population and especially to patients.
The present results showed no effect of the time of the day on the variability in lumbar lordosis and
sacrum orientation in all three cohorts. This is in contrast to previous measurements on spinal flexibility
12
which clearly showed diurnal variations (intra-day variations) in spinal stiffness. A simple flexibility test
by monitoring temporal changes in the fingertip-to-floor distance could potentially indicate the trunk
“stiffness/flexibility” and temporal variations therein with the maximum stiffness occurring early in the
morning after rising (Gifford, 1987). Maximum flexibility occurs late in the evening before going to bed
(Adams and Dolan, 1996). A similar response is seen in the lumbar flexion with the maximum stiffness
early in the morning and the maximum flexibility late in the afternoon (Gifford, 1987; Manire et al.,
2010). This corroborates findings of Adams et al. (1987) who showed that the range of trunk flexion
increased by about 5° during the day. These previous findings would suggest that also the variability in
repeated standing phases is time dependent, which was however not the case in the current analyses.
Given the high impact of a reproducible posture, practical recommendations for patient positioning
during X-ray radiography have been given by different authors. Dewi et al. (2010) suggested a balancing
plate, BalancAid, which consists of a square board with a cylindrical disc at the center point attached at
the center of the bottom. This design should realize a forced balance in the sagittal and frontal planes.
The balancing effect from the device forces the subject to stand balanced and directs the posture in a
specific upright position. The authors showed a greater reproducibility when using BalancAid compared
to standing on the ground by grasping a supporting bar. However, it has to be noted that the position
during standing on such an apparatus is not comparable to naturally relaxed standing. Koreska et al.
(1978) implemented the ‘‘Throne’’ to reproduce the positioning of the patients. However, this device
merely enabled the patient to be imaged in a sitting position, whereas the standardized method for
curvature measurement using X-ray requires standing. Other researchers showed that the arm position
is not only important in having an optimal vertebral visibility in X-ray radiographs but also plays an
important role in the generation of a reliable three-dimensional representation of the spine (Hayashi et
al., 2009; Schmidt and Gassel, 1994; Vialle et al., 2005).
13
Given that from one standing posture to the next standing posture, the study participants performed
different exercises (e.g., flexion or extension), it is likely that some of the observed variability was due to
differences in exposures. Such results would highlight the need for the development of protocols capable
of making standing posture more reproducible. The present results showed a tendency towards larger
variability in lumbar lordosis after 3 times flexion (1st exercise) and smaller variability after 3 times
extension (2nd exercise). Although these differences were not significant, the present results support the
development of standardized protocols; the including exercises, however, have to be investigated in
future studies.
In accordance with other non-invasive measurement tools, Epionics SPINE has certain limitations. First, it
should be noted that the Epionics SPINE system measures the back shape and not directly the curvature
of the lumbar spine and the orientation of the sacrum. Recent studies have found a significant
correlation between lumbar lordosis assessed via the back shape and determined radiologically only for
subjects with a body mass index (BMI) <27.0 kg/m² (Adams et al., 1986; Guermazi et al., 2006; Stokes et
al., 1987). In our own validation studies, we could additionally show that the correlation between the
back and spinal shape is poor in overweight and obese persons, which limits this study to normal-weight
subjects (BMI<27.0 kg/m2). Therefore, to ensure a strong correlation between back shape and underlying
spinal structures, only subjects with a BMI <27.0 kg/m² were included in the asymptomatic cohort. For
the LBP patients’ cohort, this criterion could not be fulfilled and therefore, the lumbar lordosis measured
with Epionics cannot be directly transferred to the actual shape of the spine. However, since the study
focused not on the validity of the spinal shape measurements, but on the variability in posture between
repetitive measurements, the authors assumed this a minor limitation. Moreover, the acceleration
sensors estimate the sacrum orientation from the spina iliaca posterior superior. This procedure is in
accordance with other non-invasive measurement approaches (Granata and Sanford, 2000; Maduri et
14
al., 2008; Tafazzol et al., 2014), but does not directly reflect clinically relevant sacrum or pelvic
parameters, which can only be obtained from radiographs.
The sensor stripes are seated inside hollow plasters, which are taped along their entire length to the
subject's back and allow the sensors to slide relative to the back's surface. The elastic fibers in the
plasters are aligned longitudinally to allow stretching during flexion and extension of the subject's back.
The plasters are able to elongate by about 50% (24 cm) of its original length which is much more than
the maximum value of 13 cm found in the present study. In the transverse direction (perpendicular to
the subject’s back), the plasters are least compliant to avoid deviations of the stripes in both
perpendicular directions and to ensure that the sensors remain closely attached to the subject's back.
Due to possible relative motion of the sensor stripes inside the hollow plasters and due to the large
stiffness of the sensor stripes in comparison to the skin, the measurement is less sensitive to skin
movements. Therefore, the measured variations in lumbar lordosis and sacrum orientations are assumed
to be due mainly to the inherent irreproducibility and not because of detachment of sensors.
It can be concluded that standing is highly individual and poorly reproducible. The reproducibility was
not affected by age, gender, BMI, body height and body weight. Back pain patients and athletes did not
show a different behavior to asymptomatic non-athletes. The number of standing phases also showed no
positive effect on the reproducibility. Therefore, it should be considered that each examination in
standing and the resulting measurements, for example, the sacrum orientation and lordosis angle, can
greatly vary in subsequent analyses.
15
Acknowledgments
This study was partially financed by the Bundesinstitut für Sportwissenschaft, Bonn, Germany
(MiSpExNetwork).
Conflict of Interest
There is no conflict of interest.
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Table and figures caption
Table 1 Data for asymptomatic subjects (non-athletes, soccer players) and low back pain (LBP) patients.
Median and ranges are given for age, body height, body weight and body mass index (BMI).
Figure 1 The Epionics SPINE system affixed to a volunteer’s back in standing. The system consists of two
flexible sensor strips utilizing strain-gauge sensors, tri-axial accelerometers and a storage unit.
Demonstration of the assessment of the total lordosis angle, which is the sum of all lordotically curved
segments during standing (average lordosis range highlighted in green: S1–S6) as well as the orientation
of the sacrum given by ‘α’, with respect to the vertical direction. The measurement protocol consisted of
six standing phases and six exercises. Each exercise was repeated three times before going to the next
exercise. Standing was recorded before the first flexion and after each exercise.
Figure 2: Box plots for sacrum orientation and lumbar lordosis. The upper diagram represents the entire
cohorts, the lower diagram summarizes age- and gender-adjusted data. Box plots are based on the
median of all six standing phases. Dashed lines indicate statistical significances.
Figure 3: Number of asymptomatic subjects classified into groups of different variability ranges in sacrum
orientation and lumbar lordosis in six repeated standing phases. Diagrams ①-④ show the relative
variations of sacrum orientation and lumbar lordosis of six individuals for all standing phases: ① and ②
10–20%, ③ >50% and ④ 40–50%. The bars represent the entire cohort. The dashed lines indicate
significant differences.
Figure 4: Relative number of subjects (with respect to the cohort size) classified into groups of different
variability ranges in sacrum orientation and lumbar lordosis in six repeated standing phases.
Figure 5: Classification of subjects into groups of different variability ranges in sacrum orientation and
lumbar lordosis in six repeated standing phases. In contrast to Fig. 5, absolute values are given on the
horizontal axis.
Figure 6: Scatter plot with variability in sacrum orientation and lumbar lordosis vs. body height, body
weight and age. The median of all six standing phases are shown. The plots are presented for the
asymptomatic cohort, except for the influence of the body weight (second line), where the results of the
LBP patients are also shown because they cover a greater body-weight range.
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21
22
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Table 1 Data for asymptomatic subjects (non-athletes, soccer players) and low back pain (LBP) patients. Median and ranges are given for age, body height, body weight and body mass index (BMI).
study groups number
women / men
Age
(y)
body height
(cm)
body weight
(kg)
BMI
(kg/m2)
asymptomatic subjects
(non-athletes)
w: 187 36 (20-75) 168 (148-184) 61 (45-88) 22.0 (16.7-26.9)
m: 145 39 (20-74) 180 (159-206) 76 (55-98) 23.4 (17.9-26.9)
soccer players m: 21 23 (19-28) 181 (163-193) 79 (63.3-111) 23.8 (21.4-26.5)
LBP patients w: 45 57 (24-84) 167 (152-189) 75 (52-120) 26.5 (19.8-44.1)
m: 38 54.5 (25-80) 181.5 (164-199) 93 (74-150) 30.0 (21.2-42.4)