Archives of Physical Medicine and Rehabilitation
Volume 90, Issue 1 , Pages 127-135, January 2009

Energy Transfer Across the Lumbosacral and Lower-Extremity Joints in Patients With Low Back Pain During Sit-to-Stand

  • Gary L. Shum, PhD

      Affiliations

    • School of Health Professions, University of Plymouth, Plymouth, UK
    • ,
  • Jack Crosbie, PhD

      Affiliations

    • School of Physiotherapy, University of Sydney, Sydney, Australia
    • ,
  • Raymond Y. Lee, PhD

      Affiliations

    • School of Human and Life Sciences, Roehampton University, London, UK
    • Corresponding Author InformationReprint requests to Raymond Y. Lee, PhD, School of Human and Life Sciences, Roehampton University, Whitelands College, Holybourne Ave, London, SW15 4JD, UK

Article Outline

Abstract 

Shum GL, Crosbie J, Lee RY. Energy transfer across the lumbosacral and lower-extremity joints in patients with low back pain during sit-to-stand.

Objective

To examine the transfer of energy through the pelvis and the lower limb during sit-to-stand (STS) in low back pain (LBP) subjects with or without a straight-leg raise sign.

Design

Cross-sectional.

Setting

Biomechanics laboratory.

Participants

Three groups, each of 20 subjects, participated. The first group consisted of asymptomatic subjects, and the other 2 groups of consisted of LBP subjects (duration between 7 days and 12 weeks) with and without a straight-leg raise sign.

Interventions

Not applicable.

Main Outcome Measures

The work done and the power of the pelvis, thigh, and leg segments during STS were determined.

Results

Energy was transferred from the pelvis to the thigh segment and then to the leg segment, and this was achieved mainly by passive mechanisms. The power flow of the pelvis segment was significantly decreased in subjects with LBP. Although the power of the lower-limb segments was decreased, the total work done of these segments was increased.

Conclusions

STS is a more energy-demanding and less efficient task for subjects with LBP, either with or without a positive straight-leg raise sign. Such increases in energy demand may further exacerbate back pain, and treatment should be developed to restore a more efficient energy transfer pattern.

Key Words: Back pain, Energy transfer, Hip, Kinetics, Rehabilitation, Spine

List of Abbreviations: CMC, coefficient of multiple correlation, ICC, intraclass correlation coefficient, LBP, low back pain, STS, sit-to-stand, 3D, 3-dimensional, VAS, visual analog scale

 

PEOPLE WITH LOW BACK PAIN have been found to have reduced joint range, reduced extensor moments, and muscle powers at the lumbar spine and hips.1, 2, 3, 4, 5 Such impairment may result in various forms of functional disability, which can profoundly affect quality of life.6

We have previously shown that LBP imposes significant limitations in motion of the lumbar spine and hips and compromises lumbar-hip coordination.2, 3 We have also found that LBP is associated with a significant decrease in lumbar extensor muscle moments and peak power generation and absorption but an increase in the axial rotation moment during activities such as STS.4 These kinetic changes may represent antalgic compensations that reduce loading and protect spinal tissues, and it is possible that they will have an impact on the energy transfer between segments in the spine, pelvis, and the lower-limb segments.

Patients with back pain and a positive straight-leg raise sign are generally more disabled than patients with LBP alone,7 and sciatica is one of the factors that may contribute to the development of chronic LBP.8 Previous studies showed that subjects with a positive straight-leg raise sign exhibited more profound changes in both the movement patterns and kinetics of the lumbar spine when compared with healthy subjects.4, 5, 9 It may be hypothesized that a straight-leg raise sign is associated with changes in the mechanical properties of the neural tissues and the muscles of the leg, and this subgroup of subjects with LBP may thus develop different changes in energy transfer. However, this hypothesis needs to be investigated experimentally.

STS is an activity in which transference of energy from 1 segment to another is critical to successful performance, yet there has been no study investigating the energetics of this activity both in healthy subjects and those with back pain. Exploring this aspect of the biomechanics can provide insight into the efficiency of movement and the interactions between energy flow and movement coordination. Clinically, inefficient energy transfer will place more demand on the spine during activities of daily living and may, in turn, further exacerbate back pain. Clinically, it is important to recognize the association between pain and energy transfer. For instance, energy flow can be restored by appropriate pain relief treatment if the abnormal pattern is caused by pain. However, if changes in energy flow are the causes of pain, we will need to examine the role of active and passive mechanisms of energy flow. This study will also study these mechanisms in subjects with back pain, which is largely unknown. Such information will allow us to develop treatment strategies such as exercise or motor re-education that will target the appropriate active and/or passive mechanisms so that the efficiency of energy transfer can be restored.

The purpose of this study was to investigate the effects of back pain, with and without limitation in the straight-leg raise sign, on the transfer of mechanical energy through the pelvis and the lower limb during STS. Power is the rate of energy flow or doing work from 1 segment to another. In this study, we determined the flow of power through the active and passive tissues of various body segments. We hypothesized that the presence of LBP would significantly alter the active and passive power flow of the body segments when compared with asymptomatic subjects.

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Methods 

Participants 

Three groups, each consisting of 20 subjects, participated (table 1). Group 1 participants had no history of back pain that had required medical attention previously. Groups 2 and 3 consisted of subjects with LBP (duration between 7 days and 12 weeks). Group 2 participants presented with a negative straight-leg raise test, whereas group 3 participants presented with a positive straight-leg raise test.10, 11

Table 1. Subject Characteristics
CharacteristicsGroup 1 AsymptomaticGroup 2 LBPGroup 3 LBP With SLR
Sample size202020
Sex (men/women)12/811/913/7
Mean age (y)38.5±6.239.8±8.240.4±5.2
Mean height (m)1.66±0.081.66±0.101.70±0.07
Mean body weight (kg)59.9±9.958.7±7.261.7±9.0
Mean onset of pain (wk)—5.2±1.85.3±1.9
Mean VAS—6.1±0.86.5±1.2
Mean Oswestry Disability Index—22.8±6.924.1±6.5
Mean angle of SLR79.5±2.280.0±0.047.8±8.2
Side of pain—Left=10Left=14
Right=10Right=6
Leg length (from greater trochanter to floor) (m)0.852±0.0430.850±0.0670.856±0.051
Lumbar spine length (from L1 to S2) (m)0.134±0.0240.134±0.0220.137±0.023
Waist (m)0.913±0.0680.935±0.0510.933±0.078

NOTE. Values are expressed as mean ± SD. There were no significant differences among the 3 groups for any variables.

Abbreviation: SLR, straight-leg raise.

Asymptomatic participants were recruited from the staff population of a local university and participants with back pain from the physical therapy department of a local hospital. In this study, back pain was defined as any pain affecting the area between the lower rib cage and gluteal folds, with or without radiation to the lower limbs. The straight-leg raise leg test was considered to be positive when the angle between the leg and longitudinal axis of the trunk was 65° or less with the reproduction of the symptoms of the usual nature and distribution.10, 11 It should be noted that this was the operational definition of straight-leg raise sign used in this study, although a positive straight-leg raise sign did not necessarily imply intervertebral disk herniation or radicular syndrome.12 Participants with back pain were diagnosed as “nonspecific back pain” by their referring doctors. All participants were subsequently assessed by a physical therapist for their suitability in this project. Participants were excluded if they had motor weakness, sensory loss, or asymmetric reflexes that may indicate nerve root dysfunction or radicular syndrome. Participants with neurologic disorders, infectious diseases, trauma, factures, and dislocations of their spine and lower limb were also excluded. None of the participants was involved in any workers' compensation.

Subjects rated the severity of their pain by using a VAS of 0 to 10, and their disability level was evaluated by using version 2.0 of the Oswestry Disability Index questionnaire.13 Informed consent was obtained before participation in the study, which was approved by the Human Ethics Committees of the University of Sydney (reference no. 04-2005/2/8148).

Instrumentation 

Two sets of 3SPACE Fastrak,a comprising 8 sensors placed over the foot, lower leg, thigh, sacrum, and the L1 spinous process were used to measure the 3D movements of the segments.14 Data were collected at a frequency of 30Hz per sensor. Two nonconductive force platesb with a sampling frequency of 120Hz were placed underneath the feet to measure ground reaction forces during the activity. Signals from the 2 Fastrak systems and the force plates were synchronized.

Procedure 

Participants were seated on a stool with neither an armrest nor a backrest that provided support from the ischial tuberosities to the middle of thighs. The stool height was 110% of knee-floor length, and the foot position was maintained throughout.15 Participants were instructed to rise freely at their comfortable speed without using their arms16 while looking forward, then to maintain a comfortable erect posture for 3 seconds, and then to sit down on the stool at their own speed. Each subject repeated the movements 3 times. A simple hand-activated switch, which was made of a simple signal-pulse generation box, was used to record the onset of additional pain. Each subject was instructed to press the button of the pain switch to record any increase in the back and/or leg pain symptoms during the activity. A signal pulse would then be generated and transmitted to the computer for recording the time of the pain occurrence. Thus, the effect of additional pain caused during the movement on the kinematics and kinetics could be analyzed.

The experiment was conducted by the same physical therapist who performed the pre-enrollment examination.

Data Reduction 

A 3D, 7-segment biomechanical model was developed to calculate the reaction forces and moments at the ankle, knee, hip, and L5/S1 joints.4 The positions of the bony landmarks including the head of the second metatarsal, medial, and lateral malleoli; medial and lateral femoral condyle; greater trochanter; posterior superior iliac spines; anterior superior iliac spines; sacrum; and the tip of L5 spinous process were determined by using a Fastrak sensora mounted on a wooden probe. Joint center locations were estimated according to the recommendations of the International Society of Biomechanics17, 18 and L5/S1 joint center from Chaffin et al.19 Anthropometric values for link lengths, masses, principal moments of inertia, and center of mass locations were derived from the regression equations by Shan and Bohn20 according to each subject's height, weight, sex, and race.

Data were processed in Matlab.c Standard 3D inverse dynamic calculations proceeded sequentially from each foot to the L5/S1 joint; however, it should be noted that kinetic analysis can be examined only from the time the force plates have the full support of the body weight (ie, the instant when the legs were off the seat, as indicated as time 0 in Fig 1, Fig 2).

Analysis of Power Flow and Work 

Power (P) is the rate of energy transfer or doing work, which is the amount of energy transmitted per unit of time from 1 body segment (eg, pelvis) to another (eg, thigh). Figure 3 shows the power flow across the thigh as an example, and similar analysis was performed for the L5/S1 joint and other joints of the lower limb. The total power flow of each segment (Psegment) was composed of passive (Ppassive) and active mechanisms (Pactive) at the proximal (Pproximal) and distal (Pdistal) ends of the segment. Passive power flow was derived from joint reaction force and translational velocity of the joint, whereas the active power represents energy flow because of muscle work (see fig 3).21, 22 Power can be transferred into or out of a segment across the joint at the proximal and distal ends of a segment. Positive segmental power indicates that energy being transferred into the segment, and negative segmental power indicates that energy being transferred out of the segment.22, 23

  • View full-size image.
  • Fig 3. 

    Diagrams showing load and power flow analysis with the thigh segment as an example. (A) Load analysis. M and F are the moments and forces acting at the hip (proximal) and knee (distal) of the thigh segment and ω and v the angular and linear velocities of the segments. The subscript p and d represent proximal and distal, respectively. (B) Power flow at the proximal () and distal ends () of a body segment. Passive and active power flow are also shown.

The work done on each segment was calculated from the area under the segmental power-time curve during each movement. All the previously described variables were normalized according to body weight and leg length (defined as distance from greater trochanter to floor) to account for individual variations in these anthropometric measures.24

Statistical Analysis 

The CMC25 was calculated to determine the degree of similarity of the 3 sets of segmental power-time curves. The consistency of the primary variables over the 3 trials within each subject was determined by using ICC3,1. The dependent variables in this study were segmental power patterns and work done of the pelvis, thigh, and leg segments. The values of the right and left side of the thigh and leg segments of the asymptomatic subjects were averaged for comparison with the other subject groups. For the 2 symptomatic groups, comparison of the left and right sides in these groups was not meaningful because different subjects had symptoms on different sides. Thus, the values of the painful and nonpainful sides were used in the analysis. Multivariate analysis of variance was used to examine any differences in each of these variables among 3 groups. A multivariate model was used because the dependent variables were related to each other, and this would avoid multiple statistical testing. A post hoc least-significant difference test was used, and the α level was set at .05.

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Results 

Subjects 

There were no significant differences in demographic data among the groups or in the value of VAS and Oswestry Disability Index between group 2 and 3 subjects (P>.05) (see table 1).

Reliability 

The mean ± SD CMC for the segmental power-time curves were found to be .97±.03, suggesting that the curves were very similar in shape on repeated measurements. The mean ICC3,1 for determining the normalized power and work done across all segments was .96±.01 and .96±.01, respectively, indicating that there were no significant differences in the normalized power and work done among the 3 trials. It is concluded that the data obtained were highly repeatable, permitting generalization of results.

Segmental Power Patterns 

The total normalized power patterns of the various body segments are shown in figure 1. The patterns were similar for asymptomatic and subjects with LBP, although the magnitude varied in different subject groups. For the asymptomatic subjects, the STS activity was initiated by negative power generated by the pelvis, with mean peak normalized power of –.28±.02 developed at .12±.04 seconds. This was followed by maximum positive power at the thigh and leg segments at .22±.06 seconds and .26±.06 seconds, respectively. This power pattern indicated that mechanical energy was transferred out of the pelvis segment into the lower-limb segments (see fig 1). Most of the power transfer happened in the first half of the STS activity. Figure 2A shows the power balance of the pelvis segment of asymptomatic subjects and the contribution of the active and passive tissues and the roles of the lumbosacral joint (the proximal joint) and the hips (the distal joint). Table 2 shows the values of active and passive power when the total power of a segment was maximal. A large portion of total power transfer was caused by passive tissue characteristics (see fig 2A). Moreover, the energy entering the segment at the L5/S1 (.79±.14) was less that that leaving the segment at the hips (–1.07±0.13) so that the total power was negative, indicating that energy was transferred from the pelvis to the lower limbs.

Table 2. Mean ± SD Normalized Segmental Power Transfer at the Proximal and Distal End of the Segment When the Total Power Was Maximal
Group 1: AsymptomaticGroup 2: LBPGroup 3: SLR
Pelvis
Passive−0.27±0.02−0.18±0.04⁎−0.18±0.06⁎
Active−0.01±0.01−0.01±0.01−0.02±0.01
L5/S10.79±0.140.80±0.180.77±0.14
Hip joint−1.07±0.13−0.99±0.21−0.98±0.19
Total−0.28±0.02−0.19±0.04⁎−0.20±0.06⁎
Right SideLeft SidePSNPPSNP
Thigh
Passive0.43±0.060.42±0.090.30±0.09⁎0.29±0.08⁎0.28±0.08⁎0.28±0.05⁎
Active0.05±0.100.05±0.100.04±0.080.04±0.080.04±0.050.04±0.12
Hip joint0.94±0.120.94±0.180.58±0.15⁎0.58±0.25⁎0.56±0.20⁎0.56±0.16⁎
Knee joint−0.46±0.11−0.47±0.16−0.25±0.10⁎−0.25±0.10⁎−0.24±0.11⁎−0.25±0.05⁎
Total0.48±0.130.48±0.220.33±0.12⁎0.33±0.11⁎0.31±0.09⁎0.31±0.09⁎
Leg
Passive0.32±0.070.33±0.090.21±0.05⁎0.21±0.05⁎0.20±0.08⁎0.21±0.04⁎
Active0.01±0.040.01±0.020.02±0.020.02±0.020.01±0.010.01±0.02
Knee joint0.32±0.070.33±0.080.22±0.05⁎0.22±0.06⁎0.21±0.08⁎0.21±0.05⁎
Ankle joint0.01±0.020.01±0.010.01±0.020.01±0.020.01±0.010.01±0.01
Total0.33±0.070.34±0.080.23±0.05⁎0.23±0.05⁎0.22±0.08⁎0.22±0.05⁎

Abbreviations: NP, nonpainful side; PS, painful side; SLR, straight-leg raise.

⁎P<.05, significant difference in symptomatic subjects when compared with asymptomatic subjects (group 1).

Regarding the thigh and leg segments (figs 2B and 2C), power transfer was also mainly accomplished by the passive tissues. For both segments, the total power was positive, indicating that energy was entering the segments from the proximal joint and leaving at the distal joint (see table 2). The magnitude of power at the proximal joint was larger than that at the distal joint and in the leg segment; the ankle power was of very small magnitude.

Work Done 

Table 3 shows the work done on the body segments. For all 3 segments, the magnitude of work done on the joint (passive power flow) was much larger than that of the muscles (active power flow).

Table 3. Mean ± SD Normalized Work Done by Body Segments
Group 1: AsymptomaticGroup 2: LBPGroup 3: SLR
Time (s)1.3±0.12.1±0.6⁎2.1±0.8⁎
Pelvis
Passive−0.13±0.02−0.16±0.01⁎−0.16±0.02⁎
Active0.01±0.010.01±0.010.01±0.01
L5/S10.35±0.060.67±0.06⁎0.68±0.08⁎
Hip joint−0.61±0.06−0.817±0.063⁎−0.802±0.058⁎
Total−0.13±0.01−0.17±0.01⁎−0.17±0.03⁎
Right SideLeft SidePSNPPSNP
Thigh
Passive0.18±0.020.18±0.040.28±0.05⁎0.28±0.06⁎0.27±0.03⁎0.27±0.04⁎
Active0.01±0.030.01±0.030.01±0.020.01±0.020.01±0.010.01±0.01
Hip joint0.43±0.080.43±0.110.57±0.09⁎0.56±0.12⁎0.57±0.07⁎0.55±0.06⁎
Knee joint−0.28±0.12−0.27±0.12−0.27±.079−0.26±.075−0.28±0.06−0.27±0.06
Total0.20±0.060.20±0.090.29±0.05⁎0.29±0.09⁎0.29±0.04⁎0.30±0.07⁎
Leg
Passive0.17±0.030.18±0.030.19±0.030.19±0.030.19±0.040.19±0.07
Active0.00±0.010.00±0.010.00±0.010.00±0.010.00±0.010.00±0.01
Knee joint0.17±0.020.17±0.020.20±0.04⁎0.20±0.05⁎0.20±0.04⁎0.21±0.04⁎
Ankle joint0.02±0.010.02±0.010.02±0.020.02±0.020.02±0.010.02±0.01
Total0.19±0.030.19±0.050.22±0.05⁎0.23±0.05⁎0.25±0.04⁎0.25±0.03⁎

Abbreviations: NP, nonpainful side; PS, painful side; SLR, straight-leg raise.

⁎P<.05, significant difference in symptomatic subjects when compared with asymptomatic subjects (group 1).

Differences Among Groups 

Subjects in all groups had similar segmental power flow patterns, but the amplitudes varied among groups. There was a significant decrease in total power transfer out of the pelvis segment in symptomatic groups compared with the asymptomatic group (see table 2) (P<.05). This involved a significant decrease in the passive power flow out of the segment (see table 2) (P<.05).

There were significant decreases in power transfer into the thigh and leg segments in symptomatic subjects (P<.05). These also involved significant decreases in the passive power transfer (P<.05) (see table 2). The decreases in power transfer were significant for both the hip and knee joints in case of the thigh segment, but the decrease was significant only for the knee in case of the leg segment.

The total work done on the pelvis, thigh, and leg segments and the work done by passive flow on the pelvic and thigh segments was significantly increased in symptomatic subjects (see table 3) (P<.05). The work done on the L5/S1, hip, and knee joints was also significantly increased in subjects with LBP. The time required to perform the STS activity was 1.3±0.1 seconds, 2.1±0.6 seconds, and 2.1±0.8 seconds for groups 1, 2, and 3, respectively. The increase in work done on the various segments was related to the increased time to perform the work. There were no significant differences in any segmental work done between group 2 and 3 symptomatic subjects. During sit-to-stand, no subjects in the symptomatic groups pressed the pain recording device.

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Discussion 

Most previous studies on intersegmental energy transfer have focused on locomotion in healthy subjects.26 This is the first study to investigate the effect of LBP on the power flow of the pelvis, thigh, and leg segments during STS. The results generally showed that LBP altered passive power flow in the pelvis and lower-limb segments and brought about significant increase in work done by these segments. These results were highly repeatable and the patterns of segmental power flow were consistent. By using the segmental power data obtained in this study, a statistical power analysis was performed. The effect size was found to be 2.12, and with (P=.05) a sample size of 20 per group, the power was found to be .95, which was sufficiently large to reveal any significant differences observed in this study. From the statistical point of view, we conclude that we are able to make valid conclusions with the experimental observations.

Energy can be transferred actively between segments by concentric or eccentric muscle work22, 23 and by a passive process in which joint forces redistribute mechanical energy among the body segments. From the results of this study, the passive power flow of the various segments was the major means of energy transfer during STS. The ligaments and the passive components of the muscle-tendon complexes are important in the storage and release of energy.27

The results of the present study revealed that mechanical energy was transferred from the pelvis to the thigh segment and then from the thigh to the leg segment. The capacity to transfer energy to distal segments by the pelvis through passive power flow was significantly decreased in symptomatic subjects. LBP not only affects the pelvis segment but also the lower-limb segments. It is interesting to note that the power of the lower-limb segments is decreased, but the total work done by these segments is increased. The kinetic chain loses its ability to transfer power through active and passive power flow, and STS is a more energy-demanding and less efficient task for such patients.

In a previous study, we reported that there was a significant decrease in the extensor muscle moments and joint muscles power generated by the lumbar spine and hips, which effectively protects tissues from pain in subjects with subacute LBP.4 This reduction in load may lead to muscle atrophy and changes in the passive mechanical properties of muscles and ligaments.28, 29, 30, 31 The resulting decreased translational and angular velocities of the body segments contribute to the changes in power flow as observed in our subjects with LBP. Adaptive changes in the stiffness and viscous properties of the passive system, for instance, will affect the work done by the tissues and therefore compromise the energy transfer capacities of the body segments. Moreover, it has also been hypothesized that the vicious cycle of back pain starts with subfailure injuries in the passive system (ie, soft-tissue injury), resulting in faulty proprioception and therefore corrupted muscle coordination.32 This may further explain why the power transfer properties are compromised in subjects with LBP.

Previous in vitro studies show that passive straight-leg raising causes traction on the lower lumbar nerve roots, pulling them caudally between 1.4 and 4mm. Such movement of the nerve root with accompanying pressure contact between the nerve root and the intervertebral disk may lead to an increase in radiating leg pain.33, 34, 35 Our previous studies 2, 3 showed that patients with positive straight-leg raise had significantly altered spinal and hip kinematics during STS when compared to patients with back pain alone. However, this study did not show significant differences in segmental power balance and work done between the 2 groups of patients with LBP. Other studies36 have shown that LBP patients with a positive straight-leg raise have increased stiffness of the hamstring muscles, which may alter the segment forces and moments developed at the spine, hips, and knees.

No subjects in the symptomatic groups pressed the pain-recording device, indicating that there was no change in pain during STS and that the observed changes in energy transfer were not immediate antalgic responses. They were not because of changes in pain during the movement but possibly altered mechanical properties of the lumbar spine and hip in subjects with LBP.

This study showed that back pain was associated with compromised energy transfer and power imbalance. This will place more demand on the spine during activities of daily living and may in turn further exacerbate back pain, resulting in a vicious cycle. STS is a very common everyday activity, and its mechanical efficiency must not be compromised. The present study revealed the relationship between back pain and power balance, but it is still unclear if back pain leads to adaptive changes in power balance or if changes in power balance would lead to back pain. Future studies should examine the cause and effect of the relationship, and such knowledge will help decide the most appropriate therapy for subjects with back pain. If back pain is the cause, treatment should be directed at pain relief, which would then lead to the restoration of power balance. However, if abnormal power balance is the cause of back pain, studies would be required to study how appropriate intervention could be used to restore the energy transfer of the mechanical system.

Another important clinical finding of this study was that the power flow of the spine and lower limbs was largely achieved by passive mechanisms, and this was significantly compromised in patients with back pain. It was previously shown that LBP was associated with changes in abnormal velocity-displacement relationship and abnormal joint forces.2, 3, 4 These explained the observed changes in passive power flow in this study. If power flow was to be restored, this could not be achieved clinically by simple strengthening exercise of the muscles but would require the restoration of normal joint reaction forces and velocities that contribute to the power of a joint. Therefore, it may be necessary to use exercise programs that maximize passive control of the spine. These exercises may include stretching of the passive tissues and exercises that aim to re-educate movement patterns and promote joint coordination. However, further research will be required to develop specific exercise protocol and to examine their clinical effectiveness.

Study Limitations 

One limitation of the present study was that the active power flow represents the net effect of muscle contraction, and we have no information about the contribution of various trunk muscles to power flow. The interpretation of passive power flow was also limited similarly because it did not represent specific anatomic structures but rather the net effect of joint reaction forces and velocities. Therefore, we are unable to suggest rehabilitation of specific anatomic structures to restore power flow. It is clinically essential that future studies will look into this using biomechanical models and electromyography.

The observations of this study were consistent, and the significant statistical results could be generalized to the population of middle-aged subjects with subacute LBP. Future research should examine the energy transfer in other patient populations such as those with acute and chronic back pain who may exhibit different energy transfer patterns. It would also be useful to study the electromyographic activities of the muscles and to include biomechanical models that will determine the contribution of various passive tissues to power flow. Moreover, as pointed out earlier, future research should examine the cause-and-effect relationship between back pain and altered power flow.

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Conclusions 

Energy is transferred from the pelvis to the thigh and then from the thigh to the leg during STS. Such energy transfer is largely achieved by passive mechanisms across the joints. The capacity to transfer energy to distal segments by the pelvis is significantly decreased in symptomatic subjects. Although the power of the lower-limb segments is decreased, the total work done on these segments increases. The kinetic chain loses its ability to transfer power efficiently, and the STS activity is a more energy-demanding activity for patients with LBP. Such increases in energy demand may further exacerbate back pain, and treatment should be developed to restore the energy transfer patterns.

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References 

  1. Esola MA, McClure PW, Fitzgerald GK, Siegler S. Analysis of lumbar spine and hip motion during forward bending in subjects with and without a history of low back pain. Spine. 1996;21:71–78
  2. Shum GL, Crosbie J, Lee RY. Effect of low back pain on the kinematics and joint coordination of the lumbar spine and hip during sit-to-stand and stand-to-sit. Spine. 2005;30:1998–2004
  3. Shum GL, Crosbie J, Lee RY. Symptomatic and asymptomatic movement coordination of the lumbar spine and hip during an everyday activity. Spine. 2005;30:E697–E702
  4. Shum GL, Crosbie J, Lee RY. Three-dimensional kinetics of the lumbar spine and hips in low back pain patients during sit-to-stand and stand-to-sit. Spine. 2007;32:E211–E219
  5. Wong TK, Lee RY. Effects of low back pain on the relationship between the movements of the lumbar spine and hip. Hum Mov Sci. 2004;23:21–34
  6. Cox ME, Asselin S, Gracovetsky SA, et al. Relationship between functional evaluation measures and self-assessment in nonacute low back pain. Spine. 2000;25:1817–1826
  7. Frymoyer JW. Back pain and sciatica. N Engl J Med. 1988;318:291–300
  8. Legrand E, Bouvard B, Audran M, Fournier D, Valat JP. Spine Section of the French Society for Rheumatology (Sciatica from disk herniation: medical treatment or surgery?). Joint Bone Spine. 2007;74:530–535
  9. Pearcy M, Portek I, Shepherd J. The effect of low-back pain on lumbar spinal movements measured by three-dimensional X-ray analysis. Spine. 1985;10:150–153
  10. Rebain R, Baxter GD, McDonough S. A systematic review of the passive straight leg raising test as a diagnostic aid for low back pain (1989 to 2000). Spine. 2002;27:E388–E395
  11. Tafazzoli F, Lamontagne M. Mechanical behaviour of hamstring muscles in low-back pain patients and control subjects. Clin Biomech. 1996;11:16–24
  12. Jönsson B, Strömqvist B. The straight leg raising test and the severity of symptoms in lumbar disc herniation (A preoperative evaluation). Spine. 1995;20:27–30
  13. Fairbank JC, Pynsent PB. The Oswestry Disability Index. Spine. 2000;25:2940–2952
  14. Lee RY. Kinematics of rotational mobilisation of the lumbar spine. Clin Biomech. 2001;16:481–488
  15. Khemlani MM, Carr JH, Crosbie WJ. Muscle synergies and joint linkages in sit-to-stand under two initial foot positions. Clin Biomech. 1999;14:236–246
  16. Carr J, Gentile A. The effect of arm movement on the biomechanics of standing up. Hum Mov Sci. 1994;13:175–193
  17. Leardini A, Cappozzo A, Catani F, et al. Validation of a functional method for the estimation of hip joint centre location. J Biomech. 1999;32:99–103
  18. Wu G, Siegler S, Allard P, et al. Standardization and Terminology Committee of the International Society of Biomechanics ISB recommendation on definitions of joint coordinate system of various joints for the reporting of human joint motion—part I: ankle, hip, and spine (International Society of Biomechanics). J Biomech. 2002;35:543–548
  19. Chaffin DB, Andersson GB, Martin BJ. Occupational biomechanics. New York: Wiley-Interscience; 1999;
  20. Shan G, Bohn C. Anthropometrical data and coefficients of regression related to gender and race. Appl Ergon. 2003;34:327–337
  21. Guo LY, Su FC, Wu HW, An KN. Mechanical energy and power flow of the upper extremity in manual wheelchair propulsion. Clin Biomech (Bristol, Avon). 2003;18:106–114
  22. Winter DA. Biomechanics and motor control of human movement. 3rd ed.. New Jersey: John Wiley and Sons; 2005;
  23. Zatsiorsky VM. Kinetics of human motion. Champaign: Human Kinetics; 2002;
  24. Hof AL. Scaling gait data to body size. Gait Posture. 1996;4:222–223
  25. Kadaba MP, Ramakrishnan HK, Wootten ME, Gainey J, Gorton G, Cochran GV. Repeatability of kinematic, kinetic, and electromyographic data in normal adult gait. J Orthop Res. 1989;7:849–860
  26. Siegel KL, Kepple TM, Stanhope SJ. Joint moment control of mechanical energy flow during normal gait. Gait Posture. 2004;19:69–75
  27. Martin PE, Cavanagh PR. Segment interactions within the swing leg during unloaded and loaded running. J Biomech. 1990;23:529–536
  28. Akeson WH, Amiel D, Woo SL. Immobility effects on synovial joints: the pathomechanics of joint contracture. Biorheology. 1980;17:95–110
  29. Uebelhart D, Bernard J, Hartmann DJ, et al. Modifications of bone and connective tissue after orthostatic bedrest. Osteoporos Int. 2000;11:59–67
  30. Williams PE, Catanese T, Lucey EG, Goldspink G. The importance of stretch and contractile activity in the prevention of connective tissue accumulation in muscle. J Anat. 1988;158:109–114
  31. Williams PE, Goldspink G. Connective tissue changes in immobilised muscle. J Anat. 1984;138(Pt 2):343–350
  32. Panjabi MM. A hypothesis of chronic back pain: ligament subfailure injuries lead to muscle control dysfunction. Eur Spine J. 2005;15:668–676
  33. Davis RA. A long-term outcome analysis of 984 surgically treated herniated lumbar discs. J Neurosurg. 1994;80:415–421
  34. Goddard MD, Reid JD. Movements induced by straight leg raising in the lumbo-sacral roots, nerves and plexus, and in the intrapelvic section of the sciatic nerve. J Neurol Neurosurg Psychiatr. 1965;28:12–18
  35. Summers B, Malhan K, Cassar-Pullicino V. Low back pain on passive straight leg raising: the anterior theca as a source of pain. Spine. 2005;30:342–345
  36. Halbertsma JP, Goeken LN, Hof AL, Groothoff JW, Eisma WH. Extensibility and stiffness of the hamstrings in patients with nonspecific low back pain. Arch Phys Med Rehabil. 2001;82:232–238
  • a Polhemus Inc, 40 Hercules Dr, Colchester, VT 05446.
  • b Bertec Corp, 6171 Huntley Rd, Ste J, Columbus, OH 43229.
  • c The MathWorks Inc, 3 Apple Hill Dr, Natick, MA 01760-2098.

PII: S0003-9993(08)01538-4

doi:10.1016/j.apmr.2008.06.028

Archives of Physical Medicine and Rehabilitation
Volume 90, Issue 1 , Pages 127-135, January 2009

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