3. Experimental Equipment
3.1 Three–Dimensional Motion Analysis System
A three–dimensional ultrasonic motion analysis system (CMS–HS, Zebris, Medizintechnik, Isny, Germany) was used to measure the kinematic parameters of lumbopelvic and hip joint. The motion analysis system operates with high measure-ment accuracy according to the travelling time measuremeasure-ment of ultrasound pulses. We used the intraclass correlation coefficient (ICC 3,1) to calculate the intra–rater relia-bility of active HLR and lumbopelvic rotation in the pre–intervention session and found excellent intra–rater reliability (ICC = 0.98 and 0.93, respectively).
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4. Outcome Measurements
4.1 Kinematic Data
The kinematic data obtained from the three–dimensional ultrasonic motion analysis system were used to measure the lumbopelvic rotation angle and lumbopelvic rotation movement onset during active HLR. Two sets of ultrasound triple markers were used:
one was placed on the midline of the pelvis by fastening a strap around the pelvis at the level of the posterior superior iliac spines to measure lumbopelvic kinematics (lumbopelvic rotation angle and lumbopelvic rotation movement onset) (Cynn et al.
2006; Oh et al. 2007; Park et al. 2011). The second set of triple markers was placed under on the distal 1/3 of the fibula to measure HLR. The measuring sensor, which consisted of three microphones to record the ultrasound signals from the markers, was positioned lateral to the subject on the side being tested. Angles were calibrated to 0°
relative to the prone position with the knee flexed at 90°. The sampling rate was 20
㎐, and the kinematic data were analyzed using the Win–data ver. 2.19 software (Zebris, Medizintechnik, Isny, Germany).
The lumbopelvic rotation movement onset was defined as the time at which the angle of the lumbopelvic motion exceeded a threshold of 1° (Gombatto et al. 2006).
The mean value of the lumbopelvic rotation angle was calculated from the last 5 s of isometric contraction during HLR. The mean value of three trials was calculated to determine the lumbopelvic rotation angle and the lumbopelvic rotation movement onset.
5. Procedures
The procedures included clinical measurements involved in subject recruitment and laboratory measurements during the active HLR test. Subjects first completed the following clinical tests: 1) the VAS, 2) the modified Ober’s test. Following comple-tion of the clinical tests, laboratory measurements were made. Each subject was in-structed to lie prone position (Figure 1). The starting position was prone with knee flexed at 90° on the side with the shortened TFL–ITB and the other knee extended (Gombatto et al. 2006). If the TFL–ITB was tight in both legs, the tighter of the two was designated as the test side. Before the HLR test, a thermoplastic splint de-termined by asking the subject to laterally rotate the hip as far as possible; 2) A target bar was positioned at 50% of the maximum active HLR to prevent excessive stretch-ing of the soft tissue of the hip and to provide tactile feedback to stop active HLR when the medial aspect of the distal tibia touched the target bar. The subject per-formed HLR for 10 s, including a 5–s concentric contraction and a 5–s isometric con-traction. A 1–min rest period was scheduled between trials. Movement speed and time were controlled using a metronome. The start signal was an auditory cue (beeper
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sound) emitted by the Noraxon TeleMyo system (Park et al. 2011). All subjects were familiarized with the experimental procedure for approximately 30 min prior to the testing. The subjects were instructed to rest for 10 min after the familiarization period to minimize muscle fatigue.
Figure 1. Hip lateral rotation position.
6. Interventions
The interventions were ADIM training and ADIM training plus self–stretching the TFL–ITB. Subjects in the ADIM training group performed ADIM in the prone posi-tion and were provided with visual feedback using a pressure biofeedback unit (Stabi-lizer, Chattanooga group Inc., Hixson, TN, USA; Figure 2). The 3–chamber pressure cell of the pressure biofeedback unit was inflated to 70 mmHg. The subject was asked to reduce the level of pressure by approximately 10 mmHg based on visual feedback from an analog pressure gauge during prone HLR. To perform the contraction cor-rectly, the subjects were instructed to “Pull your belly button up and in towards your spine without pelvic movement during exhalation.” It is difficult for patients with LBP to maintain a 60 mmHg level using the pressure biofeedback unit. Thus, the sub-jects were instructed to perform ADIM training 20 min a day, 7 days per week for a 2–week period.
The subjects in the ADIM training plus TFL–ITB self–stretching group were in-structed to first stretch the TFL–ITB and then ADIM. Subjects were told to perform TFL–ITB self–stretching 2 sets of 10 repetitions a day, 7 days per week, for a 2–week period (Figure 3). The TFL–ITB stretch was performed in the upright standing posi-tion with arms extended and hands clasped overhead. The leg to be stretched was ex-tended, adducted, and externally rotated and then placed behind the non–tested leg.
The subject was then instructed to exhale while slowly bending the trunk laterally in the direction opposite the test leg (Fredericson et al. 2002). The subjects were in-structed to hold the stretched position for 10 s and rest for 2 min between sets. The
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subjects were instructed to stop the exercise if it caused a sharp pain or discomfort in the lumbopelvic region. Furthermore, the subjects were told that muscle fatigue and a stretched–out feeling could be expected after each stretching session.
Figure 2. Abdominal drawing–in maneuver training using a pressure biofeedback unit.
Figure 3. Self–stretching the tensor fasciae latae–iliotibial band.
7. Statistical Analysis
Sample size and power calculations were performed using the statistical power analysis program, G*Power ver. 3.1.5 software (Franz Faul, University of Kiel, Ger-many). Kolmogorov-Smirnov tests were performed to assess whether continuous data approximated a normal distribution. Subjects were randomly allocated to the experi-mental groups using the Microsoft Excel 2007 software (Microsoft Corporation, Redmond, WA, USA); thus, we expected a homogenous distribution of variance and did not anticipate significant pre–intervention between–group differences on any out-come measure. However, we conducted an independent t–test to analyze the pre–
intervention values between groups. A paired t–tests was used to determine within–
group (before and after an intervention) changes and the independent t–test was used to determine between–group differences for each outcome measure (lumbopelvic ro-tation angle, lumbopelvic roro-tation movement onset, TFL–ITB length, and pain inten-sity). Cohen’s d statistic was used to calculate the effect size for each outcome com-parison and was calculated as the difference in the group means divided by the pooled standard deviation (Cohen 1988). All statistical analyses were performed using PASW Statistics ver. 18.0 software (SPSS, Inc., Chicago, IL, USA). The level of sig-nificance was set as α = 0.05.
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Results
1. General Characteristics of Subjects
The general characteristics of the 22 subjects including gender, age, height, weight, body mass index, and active HLR are shown in Table 2.
Table 2. General characteristics of subjects (N=22)
aADIM: Abdominal drawing–in maneuver.
bTFL–ITB: Tensor fasciae latae–iliotibial band.
cMean ± standard deviation.
dBMI: Body mass index.
eHLR: Hip lateral rotation.
p value is comparison of groups using an independent t–test.
2. Lumbopelvic Rotation Angle
The lumbopelvic rotation angle decreased significantly under the post–intervention compared with the pre–intervention (ADIM training: pre = 4.94 ± 1.18°, post = 1.82 ± 0.52°, t (10) = –2.76, p = 0.01, d = 4.22; ADIM training plus TFL–ITB self–
stretching: pre = 5.48 ± 0.92°, post = 1.53 ± 0.26°, t (10) = 19.71, p < 0.01, d = 5.95).
The ADIM training plus TFL–ITB self–stretching decreased the lumbopelvic rotation angle significantly more than the ADIM training alone (pre–intervention minus post–
intervention, ADIM training: mean difference = 3.12 ± 0.73°; ADIM training plus TFL–ITB self–stretching: mean difference = 3.95 ± 0.66°, t (20) = –2.76, p = 0.01, d
= 1.19, Figure 4).
3. Lumbopelvic Rotation Movement Onset
The lumbopelvic rotation movement onset delayed significantly under the post–
intervention compared with the pre–intervention (ADIM training: pre = 1.53 ± 0.38 s, post = 2.85 ± 0.86 s, t (10) = –5.97, p < 0.01, d = 1.82; ADIM training plus TFL–ITB self–stretching: pre = 1.58 ± 0.22 s, post = 3.56 ± 0.50 s, t (10) = –9.94, p < 0.01, d = 3.04). The ADIM training plus TFL–ITB self–stretching delayed the lumbopelvic rotation angle significantly more than the ADIM training alone (ADIM training: mean difference = 1.31 ± 0.72 s; ADIM training plus TFL–ITB self–stretching: mean dif-ference = 1.98 ± 0.65 s, t (20) = –2.23, p = 0.03, d = 0.96, Figure 5).
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4. Tensor Fasciae Latae–Iliotibial Band Length
The TFL–ITB length was measured using the modified Ober’s test and was ex-pressed as the hip horizontal adduction angle. In the ADIM training, the TFL–ITB length did not increase significantly under the post–intervention compared with the pre–intervention (ADIM training: pre = 8.09 ± 0.94°, post = 8.27 ± 1.00°, t (10) = – 1.00, p = 0.34, d = 0.29). In the ADIM training plus TFL–ITB self–stretching, the TFL–ITB length increased significantly under the post–intervention compared with the pre–intervention (ADIM training plus TFL–ITB self–stretching: pre = 8.27 ± 0.90°, post = 10.54 ± 1.43°, t (10) = –6.82, p < 0.01, d = 2.06). The hip horizontal adduction angle was significantly greater under the ADIM training plus TFL–ITB self–stretching compared with the ADIM training alone (ADIM training: mean differ-ence = 0.18 ± 0.60°; ADIM training plus TFL–ITB self–stretching: mean differdiffer-ence = 2.27 ± 1.10°, t (20) = –5.51, p < 0.01, d = 2.35, Figure 6).
5. Pain Intensity
The pain intensity decreased significantly under the post–intervention compared with the pre–intervention (ADIM training: pre = 55.90 ± 8.31 mm, post = 18.18 ± 6.03 mm, t (10) = 11.57, p < 0.01, d = 3.49; ADIM training plus TFL–ITB self–
stretching: pre = 54.54 ± 10.11 mm, post = 21.36 ± 9.51 mm, t (10) = 11.21, p < 0.01, d = 3.37). The pain intensity rating was lower in the ADIM training plus TFL–ITB
self–stretching group than in the ADIM training group; however, the difference was not statistically significant (ADIM training: mean difference = 37.72 ± 10.80 mm;
ADIM training plus TFL–ITB self–stretching: mean difference = 33.18 ± 9.81 mm, t (20) = 1.03, p = 0.31, d = 0.44, Figure 7).
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Figure 4. Lumbopelvic rotation angle between–
group differences (A: Abdominal drawing–in maneuver training group, B: Abdominal drawing–in maneuver training plus tensor fasciae latae–
iliotibial band self–stretching group)
*p = 0.01.
Figure 5. Lumbopelvic rotation movement onset between–group differences (A: Ab-dominal drawing–in maneuver train-ing group, B: Abdominal drawtrain-ing–in maneuver training plus tensor fasciae latae–iliotibial band self–stretching group) *p = 0.03.
Figure 6. Tensor fasciae latae–iliotibial band length between–group differences (A:
Abdominal drawing–in maneuver training group, B: Abdominal drawing–in maneuver training plus tensor fasciae latae–iliotibial band self–stretching group) *p < 0.01.
Figure 7. Pain intensity between–group differences (A: Abdominal drawing–in maneuver training group, B: Abdominal drawing–
in maneuver training plus tensor fasciae latae–iliotibial band self–stretching group).
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Discussion
The purpose of the present study was to compare the effect of a 2–week intervention with ADIM training or ADIM training plus TFL–ITB self–stretching on lumbopelvic rotation angle, lumbopelvic rotation movement onset, TFL–ITB length, and pain intensity during active prone HLR in people with lumbar extension rotation syndrome accompanying shortened TFL–ITB.
The pre–intervention lumbopelvic rotation angle during HLR was 4.94 ± 1.18° in the ADIM training group and 5.48 ± 0.92° in the ADIM training plus TFL–ITB self–
stretching group. These results agree with previous reports of excessive lumbopelvic motion in people with lumbar extension rotation syndrome (Gombatto et al. 2006;
Harris–Hayes, Van Dillen, and Sahrmann 2005; Hoffman et al. 2011; Scholtes et al.
2010; Van Dillen et al. 2007). Following the intervention in our study, lumbopelvic rotation was reduced to 1.82 ± 0.52° and 1.53 ± 0.26° in the ADIM training and ADIM training plus TFL–ITB self–stretching groups, respectively. Our results indicate that the lumbopelvic rotation angle decreased significantly following both interventions. Lumbopelvic rotation angle between–group differences were 3.12 ± 0.73° in ADIM training and 3.95 ± 0.66° in ADIM training plus TFL–ITB self–
stretching. Our results indicate that the ADIM training plus TFL–ITB self–stretching decreased the lumbopelvic rotation angle significantly more than the ADIM training alone, although the difference was minimal. Our results suggest that an improved abdominal control and an elongated TFL–ITB could play a greater role in minimizing
the lumbopelvic rotation angle. Our findings are consistent with previous research showing that insufficient abdominal control and shortened TFL–ITB could contribute to increased lumbopelvic rotation during active HLR (Sahrmann 2002).
The pre–intervention lumbopelvic rotation movement onset during HLR was 1.53
± 0.38 s in the ADIM training group and 1.58 ± 0.22 s in the ADIM training plus TFL–ITB self–stretching group. This implies that the early lumbopelvic rotation movement onset could be attributed to the lack of control by the abdominal muscles and the shortened TFL–ITB. This finding concurs with the results of previous studies reporting that LBP is associated with early lumbopelvic rotation during active limb movement (Sahrmann 2002; Van Dillen et al. 2007; Van Dillen, Maluf, and Sahrmann 2009; Van Dillen, and Sahrmann 2006). The results of the present study showed that the lumbopelvic rotation movement onset was significantly delayed following both interventions, suggesting that both abdominal control and stretching of the TFL–ITB contribute to the delayed lumbopelvic rotation movement onset.
Moreover, our results showed that ADIM training plus TFL–ITB self–stretching delayed the lumbopelvic rotation movement onset significantly more than the ADIM training alone, although the difference was minimal. The current study suggests that treatment may require not only training of the abdominal control, but also stretching of the TFL–ITB to delay the lumbopelvic rotation movement onset during the HLR.
The ADIM training plus TFL–ITB self–stretching group showed a significantly greater increase in the hip horizontal adduction angle than did the ADIM training alone group. The present study showed that ADIM training plus self–stretching the
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TFL–ITB elongated the TFL–ITB. Shortening of the TFL increases ITB tension resulting in excessive lumbopelvic movement to compensate. Our results are consistent with those of a previous study showing that stretching in an upright standing position with arms extended overhead is an effective method for increasing TFL–ITB length (Fredericson et al. 2002).
The level of pain intensity determined using a VAS was significantly reduced following both interventions. The level of pain intensity was lower in the ADIM training plus TFL–ITB self–stretching group than in the ADIM training group;
however, the difference was not statistically significant. Our results suggest that the reduction in pain may be associated with a reduction compressive stress induced by restricted lumbopelvic rotation during HLR. Previous studies reported that people with lumbar extension rotation syndrome have a tendency to extend and rotate the lumbar spine during lower–extremity movements. Furthemore, repetitive movement in a specific direction contributes to cumulative microtrauma of the lumbar tissue and eventually results in LBP (Maluf, Sahrmann, and Van Dillen 2000; Mueller, and Maluf, 2002).
The present study has several limitations. First, we studied the effect of the ADIM training and self–stretching the TFL–ITB using a standardized movement test, and it is not clear whether our results can be generalized to other functional activities in subjects with lumbar extension rotation syndrome. Second, in our measurement of the lumbopelvic rotation motion, the angle was calculated based on movement of the level of posterior superior iliac spine marker and did not account for motion of the
upper trunk that may have contributed to lumbopelvic rotation. Third, the present study used surface markers to index bone movement; thus, artifacts resulting from skin movement were present. Because the lumbopelvic rotation movement was small, skin movement artifacts may have had an impact on our outcome measure. Finally, the 2–week test period was a short–term intervention. Further research is needed to determine the long–term effect of ADIM training and self–stretching the TFL–ITB on lumbopelvic kinematics during HLR in subjects with lumbar extension rotation syndrome.
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Conclusion
The present study compared the effect of a 2–week intervention with ADIM training or ADIM training plus TFL–ITB self–stretching on lumbopelvic rotation angle, lumbopelvic rotation movement onset, TFL–ITB length, and pain intensity during active prone HLR in people with lumbar extension rotation syndrome accompanying shortened TFL–ITB. The results indicate that compared with ADIM training alone, ADIM training plus TFL–ITB self–stretching significantly decreased the lumbopelvic rotation angle, delayed the lumbopelvic rotation movement onset, and elongated the TFL–ITB. The reported decrease in pain intensity was greater in the ADIM training plus TFL–ITB self–stretching group than in the ADIM training group; however, the difference was not significant. In conclusion, ADIM training plus TFL–ITB self–stretching performed for a period of 2 weeks may be an effective treatment for modifying lumbopelvic motion and reducing LBP.
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