Journal of Bodywork & Movement Therapies (2017) 21, 246e250
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.elsevier.com/jbmt
EX-POST FACTO STUDY
Hamstring muscle length and pelvic tilt range among individuals with and without low back pain Francis Oluwafunsho Fasuyi, PT, MSc*, Ayodele A. Fabunmi, PT, PhD, Babatunde O.A. Adegoke, PT, PhD Department of Physiotherapy, University of Ibadan, Nigeria Received 16 October 2015; received in revised form 17 February 2016; accepted 1 June 2016
KEYWORDS Leg; Low back pain; Thigh; Muscles; Skeletal
Summary Hamstring tightness has been documented not to be related to the pelvic tilt position during static standing posture, but there is limited data on the relationship between hamstring muscle length (HML) and pelvic tilt range (PTR) during the dynamic movement of forward bending. This ex-post facto study was designed to compare each of HML and PTR in individuals with low back pain (LBP) and counterparts without LBP, and the relationship between HML and PTR in individuals with and without LBP. The study involved 30 purposively recruited individuals with LBP and 30 height and weight-matched individuals without LBP. Participants’ PTR and HML were assessed using digital inclinometer and active knee extension test respectively. Data were analyzed using t-test and Pearson Correlation (r) at a Z 0.05. Participants without LBP had significantly longer (p Z 0.01) HML than those with LBP but the PTR of both groups were not significantly different. HML and PTR had indirect but not significant correlations in participants with and without LBP. Hamstring muscle length is significantly reduced in individuals with LBP but it has no significant correlation with pelvic tilt range. Pelvic tilt range reduces as hamstring muscle length increases. ª 2016 Elsevier Ltd. All rights reserved.
Introduction
* Corresponding author. Department of Physiotherapy, University of Ibadan, P.M.B 5017, G.P.O Ibadan, Nigeria. Tel.: þ234 8036142519. E-mail address: [email protected] (F.O. Fasuyi). http://dx.doi.org/10.1016/j.jbmt.2016.06.002 1360-8592/ª 2016 Elsevier Ltd. All rights reserved.
In the static standing position, four muscle groups namely; erector spinae, hamstrings, abdominals and hip flexors, are responsible for supporting and maintaining the pelvis in its neutral alignment provided the muscles’ actions are balanced (Kendall et al., 2005; Rockey, 2008). However,
Hamstring muscle length and pelvic tilt range when there is an imbalance among these muscle groups or change in posture, the pelvis is thought to tilt either anteriorly or posteriorly, with anterior pelvic tilting occurring more frequently from weakened and lengthened hamstring muscles (Kendall et al., 2005; Nguyen and Shultz, 2007). Investigation into the timing of the hip extensor muscle activity during a dynamic movement of forward bending by Leinonen et al. (2000) showed that the hamstrings are activated before the gluteus maximus, thereby suggesting that the hamstring muscles play a very pivotal role in the alignment and orientation of the pelvis. Though there seems not to be a universal agreement on what the ideal posture is, excessive anterior inclination of the pelvis has in the past been regarded as undesirable, with suggestions that alteration in movement patterns could lead to excessive loading of lumbar tissues and thereby predispose individuals to low back pain (LBP) (Norris and Matthews, 2006). Change in body alignment (static posture) and alteration of movement sequencing (dynamic posture) have hence been hypothesized as are common risk factors for LBP (Norris and Matthews, 2006). Low back pain (LBP) which is pain and discomfort localized below the costal margin and above the inferior gluteal folds with or without referred leg pain, is the price the human race is paying for attaining the upright posture (Khan and Siddiqui, 2005; Van Tulder et al., 2006). Its impact on disability has socioeconomic implications, since, from adolescence to adulthood 80e85% of people suffer from this ailment in the modern world, therefore its effective management is essential (Khan and Siddiqui, 2005; Bellew et al., 2010). In order to make effective treatment available, there needs to be detailed understanding of biomechanical changes that may be contributing to LBP. This quest for adequate information has led to research on these biomechanical changes, with current literature indicating decreased changes in hip and lumbar motion range and velocity during the dynamic movement of forward bending (FB) (Norris and Matthews, 2006). FB, a common task of daily living resulting from coordinated activity between the back extensor muscles (erector spinae) and the hip extensor muscles (glutei and hamstrings), is a coupled movement combining lumbar flexion and pelvic rotation, and is termed lumbarepelvic rhythm (Norris and Matthews, 2006), Due to the location of the hamstring muscles with their origin at the ischial tuberosities, poor hamstring flexibility may restrict anterior pelvic rotation and in turn limit FB range unless compensated for by an increase in lumbar flexion, and consequent large amount of lumbar flexion on a repeated basis and resultant LBP (Esola et al., 1996). Based on these biomechanical concepts, FB has been implicated as a possible cause of LBP, thus suggesting that a relationship exists between hamstring muscle length (HML) and pelvic tilt range (PTR) (Mohamed et al., 2002; Kendall et al., 2005). In clinical practice, testing hamstring muscle length is advocated during assessments of patients with LBP (Petty and Moore, 2000) with an argument suggesting that lengthening the hamstrings may allow greater motion to occur at the hips and therefore reduce stress on the lumbar spine, though a causal relationship between hamstring flexibility and pelvic rotation has not been fully established
247 (Bellew et al., 2010). However, Norris and Matthews (2006) have stated that hamstring tightness is not related to pelvic tilt position during the static standing posture. There is however sparse data available on the relationship between hamstring length and pelvic tilt during dynamic posture. Influences on static posture are multi-factorial with the pull of the hamstrings being balanced by both the hip flexors and the abdominal muscles, but the dynamic movement of FB has not been thoroughly investigated (Norris and Matthews, 2006) most especially in people with low back pain. With previous researches suggesting that no relationship between HML and PTR exists during static standing (Nourbakhsh and Arab, 2002; Congdon et al., 2005) and very little being known about the dynamic movement of FB, the objectives of this study were therefore to compare both HML and PTR in individuals with and without LBP and investigate the relationships between HML and PTR in either group during dynamic movement of FB.
Methodology Procedure This Ex-post facto study involved 30 individuals with mechanical low back pain who were purposively recruited from the Physiotherapy Departments of University College Hospital, Ibadan and Adeoyo State Hospital, Ibadan and 30 height and weight-matched individuals without LBP who were mainly staff and students of the University of Ibadan. Ethical approval for the study was obtained from the University of Ibadan/University College Hospital Ethics Review Committee and informed consent was obtained from all the participants after detailed explanation of the nature and purpose of the study by researcher and assurance on the confidentiality of the data obtained.
Measurement The participants’ weight and height were measured using standard methods by the International Society for Advancement of Kinanthropometry (ISAK, 2001) and recorded. Other measurements were taken using the following procedure. 1. Hamstring Muscle Length: Hamstring muscle length was measured using the self-monitored active knee extension (AKE) test (Norris and Matthews, 2006). The participants were asked to lie supine on a plinth and flex their right knee and hip to 90 . Maintaining the position of the femur with their right hand, participants were instructed not to allow the femur to move away from the hand at any point during the test. The arms of the goniometer were aligned along the femur and fibula with its centre or axis placed over the lateral knee joint line. The participants were then instructed to extend their right leg as far as possible while keeping the foot relaxed. The end position was held for 5 s, and the angle of knee extension was read off the goniometer and recorded as HML (Norris and Matthews, 2006). 2. Pelvic Tilt Range: Participant’s pelvic tilt was assessed using the procedure described by Norris and Matthews
248
F.O. Fasuyi et al.
(2006). Before testing the forward bending action, the right tibia length was measured for each participant from the lateral joint line of the knee to the inferior border of the lateral malleolus. This length was designated ‘T’. A horizontal line was then drawn to join the posterior superior iliac spines and designated ‘L’. A line was also drawn on the ground and participants stood barefooted with their feet shoulder width apart, and the backs of the heels placed on the line. A bar was positioned at distance ‘T’ from the ground line and at a height ‘T’ from the line on the ground, and held in place on a frame. An inclinometer was placed over the participants’ sacrum with its upper edge aligned with the previously drawn line ‘L’ joining the participant’s posterior superior iliac spines. The digital inclinometer was then pressed firmly against the body to make and maintain contact with the spines of the sacral vertebra through the skin. The inclinometer read zero in the starting position and participants were instructed to bend forward to touch the bar in a single smooth action, without allowing any change in the angles of their knee joints. The inclinometer reading was taken immediately, and recorded as the PTR.
Statistical analysis ShapiroeWilk test indicated that the data were normally distributed hence data were analysed using parametric statistics. Participants’ age, height, weight, HML and PTR were summarized using range, mean and standard deviation. Both HML and PTR of the LBP and no LBP groups were compared using independent t-test while the correlations between HML and PTR were explored using Pearson Product Moment Correlation at 0.05 alpha level. All statistical analyses were performed with the SPSS 16.0 evaluation software (SPSS Inc., 1989e2007, Chicago, USA).
Results Both groups had even distributions of male and female participants. Participants in the LBP group were aged 35e70 years (mean Z 53.70 8.62 years while those in the without LBP group were aged 20e41 years (mean Z 26.07 5.70 years). The LBP group was significantly older than the control group but the groups did not Table 1
differ significantly in their weight and height. The group without LBP had significantly longer (p Z 0.01) HML than the group with LBP but the groups were not significantly different in their PTR (Table 1). The negative correlations between HML and PTR in both the group with (r Z 0.07) and without (r Z 0.02) LBP were not significant.
Discussion The main purpose of this study was to compare each of HML and PTR in individuals with and without LBP and investigate the relationship between HML and PTR in these two groups during dynamic movement of FB. Individuals without LBP had significantly greater hamstring flexibility (HML) than individuals with LBP. This finding is in agreement with what previous studies have reported and could be the reason for the larger variability in pelvic tilt range (PTR) found in the group of individuals with LBP as demonstrated in this study though, the two groups were not significantly different in their PTR. There has been a suggestion in the past that, variability in PTR could be a compensatory mechanism secondary to pelvic instability since it is a common finding in patients with LBP (van Wingerden et al., 1997; Nourbakhsh and Arab, 2002). However, in view of the documented effect of age and aging on flexibility of muscles and the fact that the LBP group had significantly lesser flexibility than the group without LBP, age could be a very important confounding factor in this study. The HML obtained for individuals without LBP in this study compared well with values reported from other studies in which the participants were of similarly young and active age (Rolls and George, 2004: Norris and Matthews, 2006) as against LBP group, who were relatively older individuals recruited from hospitals. Scores from the active knee extension (AKE) test indicated that the total range of motion for the leg excursion was reduced in individuals with LBP probably as a result of the relative isolated stretching of the hamstring during hip flexion movement without significant additional assistance from either lumbar lordosis or posterior pelvic tilting when the thigh is supported actively at 90 of hip flexion. This reduced flexibility may then be explained by greater hamstring muscle tightness during the normal range of motion (20 e50 ) (Marshall et al., 2009). It must however be noted that the tightness of the hamstrings is not only peculiar to the LBP group since the increase stiffness during the normal range of motion and decrease extensibility are
Physical characteristics of participants. With LBP (n Z 30) M S.D
Age Weight (kg) Height (m) HML ( ) PTR ( )
53.70 66.83 1.66 142.10 16.20
8.62 9.50 0.08 8.85 18.47
* Z significant difference at a Z 0.05. HML Z degrees. PTR Z degrees.
Without LBP (n Z 30) Range
M S.D
35e70 51e94 1.50e1.88 123e157 29e42
26.07 69.50 1.69 147.67 9.00
p-value Range
5.70 6.50 0.05 7.64 14.96
20e41 52e83 1.54e1.77 133e163 21e30
0.00* 0.21 0.11 0.01* 0.10
Hamstring muscle length and pelvic tilt range consistent findings among all individuals (Marshall et al., 2009). This finding might have been due to the adaptation that has taken place in the passive component of the muscles over time with resultant tightness and shortness as reflected in the reading of the goniometer during the AKE test. It can then be argued that the inability of the individuals with LBP to endure the stretch resulted in the termination of movement (Halbertsma et al., 2001). This stretch tolerance may also explain the reduced HML observed among participants in this study since this may be an actual mechanical restriction within the muscle caused by increased passive stiffness and not volitional choice (Marshall et al., 2009). Norris and Matthews (2006) found no significant association between HML and PTR during forward bending among individuals who were asymptomatic of LBP though they suggested the possibility of such association in patients with LBP. Although individuals with LBP were included in this study, no significant association was also observed between HML and PTR in both the LBP and no LBP groups. Our finding concerning however conforms with that of McClure et al. (1997) of a significant difference between the hamstring muscle flexibility of symptomatic and asymptomatic individuals while the hamstring muscle length did not correlate with measures of lumbopelvic kinematics. Similarly, Halbertsma et al. (2001) found that lumbar lordosis was not different between symptomatic and symptomatic individuals, though there was a difference between their HML. Further, Nourbakhsh and Arab (2002) did not find significant relationships between HML and both pelvic tilt and lumbar lordosis. Bellew et al. (2010) however reported that hamstring extensibility strongly correlated with pelvic rotation during maximal trunk flexion in a study that involved 20 asymptomatic subjects who performed forward bending in a toe touch motion with the total range measured as the distance from the middle finger to the floor. The limited flexion movement of FB restricted to tibia tuberosities in this study may explain the reason for the difference in result. Differences in HML measurement methods employed in the different studies could have also contributed to the differences in the findings reported. Video analysis provides an accurate method of measuring pelvic motion. However, although the method has been reported to be presently available even to students in developed countries, it is hardly available to even researchers in developing countries like Nigeria. The inclinometer used in this study is however a reliable method for assessing pelvic motion in the clinical setting (Bierma-Zeinstra et al., 2001). This study is also trying to draw attention of therapist in Nigeria to this method of assessment as a baseline for lumbopelvic exercise prescription since this instrument is cheaply accessible for their use. The long held impression that tight hamstring muscle limits anterior pelvic tilt because the hamstrings attaches to the ischial tuberosity which moves superiorly as the pelvis tilts, so that the distance between the attachments of the hamstrings is increased may not be correct after all. This is because the line of action of the hamstring being almost vertical and its attachment just slightly posterior to the femoral head provides a minimal force that posteriorly rotates the pelvis to counterbalance the activities of the
249 hip flexor and keep the pelvic orientation in check. Possible limitations to findings from our study are the significant difference between the ages of the groups with and without LBP as well as our failure to categorize participants in the LBP group using more defining diagnostic criteria. Findings from this study should hence be considered along with these limitations which future studies must accommodate.
Clinical implication Changes in the length of the hamstring muscle do not necessarily have an effect on pelvic tilt in both individuals with and without LBP. Reduced hamstring muscle length has been implicated as the cause or consequence of LBP. A finding of reduced hamstring muscle length in individuals with LBP in this study is hence in line with this consensus. The practice of screening for hamstring flexibility in individuals with mechanical low back pain and prescribing stretching exercises for those with reduced hamstring muscle length is hence justified.
Conclusion We conclude that no significant relationship exists between hamstring muscle length and pelvic tilt range during forward bending in both individuals with and without low back pain. These indicate that changes in HML may not necessarily affect pelvic rotation. Participants with LBP had significantly shorter hamstring muscle length than participants without LBP but the two groups did not differ significantly in their pelvic tilt range. The significant difference between the ages of the two groups is however a possible confounding factor hence our finding should be considered with caution.
Acknowledgments The authors acknowledge the heads Department of Physiotherapy, University College Hospital, Ibadan and Department of Physiotherapy, Adeoyo State Hospital, Ibadan for their support and cooperation during data collection. We also wish to appreciate all participants in this study. We wish to report no conflict of interest and declare that we are solely responsible for the content and writing of the manuscript.
References Bellew, S., Ford, H., Shere, E., 2010. The relationship between hamstring flexibility and pelvic rotation around the hip during forward bending. Plymouth Stud. J. Health & Soc. Work (2), 19e29. Bierma-Zeinstra, S.M., Van Gool, J.J., Bernsen, R.M., Njoo, K.H., 2001. Measuring the sacral inclination angle in clinical practice: is there an alternative to radiographs? J. Manip. Physiol. Ther. 24 (8), 505e508. Congdon, R., Bohannon, R., Tiberio, D., 2005. Intrinsic and imposed hamstring length influence posterior pelvic rotation during hip flexion. Clin. Biomech. 20, 947e951. Esola, M.A., McClure, P.W., Fitzgerald, G.K., Siegler, S., 1996. Analysis of lumbar spine and hip motion during forward bending
250 in subjects with and without a history of low back pain. Spine 21 (1), 71e78. Halbertsma, J.P.K., Go ¨eken, L.N.H., Hof, A.L., Groothoff, J.W., Eisma, W.H., 2001. Extensibility and stiffness of the hamstrings in patients with nonspecific low back pain. Arch. Phys. Med. Rehabil. 82, 232e238. International Society for Advancement in Kinanthropometry (ISIAK), 2001. International Standard for Anthropometric Assessment. ISIAK, Unerdale, SA, Australia, pp. 1e133. Kendall, F.R., McCreary, E.K., Provance, P.G., Rodgers, M.M., Romani, W.A., 2005. Muscles: Testing and Function with Posture and Pain, fifth ed. Williams & Wilkins, Baltimore, MD. Khan, M.Y., Siddiqui, M.A., AprileJune 2005. Prevalence of low back pain in computer users. Pak. J. Med. Sci. 21 (2), 159e163. Leinonen, V., Kankaanpaa, M., Airaksinen, O., Hannine, O., 2000. Back and hip extensor activities during trunk flexion/extension: effects of low back pain and rehabilitation. Arch. Phys. Med. Rehabil. 81 (1), 32e37. Marshall, P.W.M., Mannion, J., Murphy, B.A., 2009. Extensibility of the hamstrings is best explained by mechanical components of muscle contraction, not behavioral measurements in individuals with chronic low back pain. Am. Acad. Phys. Med. Rehabil. 1, 709e718. http://dx.doi.org/10.1016/j.pmrj.2009.04.009. McClure, P.W., Esola, M., Schreier, R., Siegler, S., 1997. Kinematic analysis of lumbar and hip motion while rising from a forward, flexed position in patients with and without a history of low back pain. Spine 22, 552e558. Mohamed, O., Perry, J., Hiplop, H., 2002. Relationship between wire EMG activity, muscle length, and torque of the hamstrings. Clin. Biomech. 17, 569e579.
F.O. Fasuyi et al. Nguyen, A.D., Shultz, S.J., 2007. Sex differences in clinical measures of lower extremity alignment. J. Orthop. Sports Phys. Ther. 37 (7), 389e398. Norris, C.M., Matthews, M., 2006. Correlation between hamstring muscle length and pelvic tilt range during forward bending in healthy individuals: an initial evaluation. J. Bodyw. Mov. Ther. 10 (2), 122e126. Nourbakhsh, M.R., Arab, A.M., 2002. Relationship between mechanical factors and incidence of low back pain. J. Orthop. Sports Phys. Ther. 32, 447e460. Petty, N.J., Moore, A.P., 2000. Neuro-musculoskeletal Examination and Assessment: a Handbook for Therapists. Churchill Livingstone, Edinburgh. Rockey, A.M., 2008. The Relationship between Anterior Pelvic Tilt, Hamstring Extensibility and Hamstring Strength, p. 66 directed by Dr. Sandra J. Shultz. libres.uncg.edu/ir/uncg/listing.aspx? idZ243. Accessed on 7/7/2011 at 16:27. Rolls, A., George, K., 2004. The relationship between hamstring muscle injuries and hamstring muscle length in young elite footballers. Phys. Ther. Sport 5 (4), 197e187. Van Tulder, Becker, A., Bekkering, et al., 2006. European guidelines for the management of the acute nonspecific low back pain in primary care, 15 (2), S169eS191. van Wingerden, J.P., Vleeming, A., Kleinrensink, G.J., Stoeckart, R., 1997. The role of the hamstring in pelvic and spinal function. In: Vleeming, A., Mooney, V., Dorman, T., Snijders, C., Stoeckart, R. (Eds.), Movement Stability and Low Back Pain. The Essential Role of the Pelvis. Churchill Livingstone, New York, NY, pp. 207e210.
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.elsevier.com/jbmt
EX-POST FACTO STUDY
Hamstring muscle length and pelvic tilt range among individuals with and without low back pain Francis Oluwafunsho Fasuyi, PT, MSc*, Ayodele A. Fabunmi, PT, PhD, Babatunde O.A. Adegoke, PT, PhD Department of Physiotherapy, University of Ibadan, Nigeria Received 16 October 2015; received in revised form 17 February 2016; accepted 1 June 2016
KEYWORDS Leg; Low back pain; Thigh; Muscles; Skeletal
Summary Hamstring tightness has been documented not to be related to the pelvic tilt position during static standing posture, but there is limited data on the relationship between hamstring muscle length (HML) and pelvic tilt range (PTR) during the dynamic movement of forward bending. This ex-post facto study was designed to compare each of HML and PTR in individuals with low back pain (LBP) and counterparts without LBP, and the relationship between HML and PTR in individuals with and without LBP. The study involved 30 purposively recruited individuals with LBP and 30 height and weight-matched individuals without LBP. Participants’ PTR and HML were assessed using digital inclinometer and active knee extension test respectively. Data were analyzed using t-test and Pearson Correlation (r) at a Z 0.05. Participants without LBP had significantly longer (p Z 0.01) HML than those with LBP but the PTR of both groups were not significantly different. HML and PTR had indirect but not significant correlations in participants with and without LBP. Hamstring muscle length is significantly reduced in individuals with LBP but it has no significant correlation with pelvic tilt range. Pelvic tilt range reduces as hamstring muscle length increases. ª 2016 Elsevier Ltd. All rights reserved.
Introduction
* Corresponding author. Department of Physiotherapy, University of Ibadan, P.M.B 5017, G.P.O Ibadan, Nigeria. Tel.: þ234 8036142519. E-mail address: [email protected] (F.O. Fasuyi). http://dx.doi.org/10.1016/j.jbmt.2016.06.002 1360-8592/ª 2016 Elsevier Ltd. All rights reserved.
In the static standing position, four muscle groups namely; erector spinae, hamstrings, abdominals and hip flexors, are responsible for supporting and maintaining the pelvis in its neutral alignment provided the muscles’ actions are balanced (Kendall et al., 2005; Rockey, 2008). However,
Hamstring muscle length and pelvic tilt range when there is an imbalance among these muscle groups or change in posture, the pelvis is thought to tilt either anteriorly or posteriorly, with anterior pelvic tilting occurring more frequently from weakened and lengthened hamstring muscles (Kendall et al., 2005; Nguyen and Shultz, 2007). Investigation into the timing of the hip extensor muscle activity during a dynamic movement of forward bending by Leinonen et al. (2000) showed that the hamstrings are activated before the gluteus maximus, thereby suggesting that the hamstring muscles play a very pivotal role in the alignment and orientation of the pelvis. Though there seems not to be a universal agreement on what the ideal posture is, excessive anterior inclination of the pelvis has in the past been regarded as undesirable, with suggestions that alteration in movement patterns could lead to excessive loading of lumbar tissues and thereby predispose individuals to low back pain (LBP) (Norris and Matthews, 2006). Change in body alignment (static posture) and alteration of movement sequencing (dynamic posture) have hence been hypothesized as are common risk factors for LBP (Norris and Matthews, 2006). Low back pain (LBP) which is pain and discomfort localized below the costal margin and above the inferior gluteal folds with or without referred leg pain, is the price the human race is paying for attaining the upright posture (Khan and Siddiqui, 2005; Van Tulder et al., 2006). Its impact on disability has socioeconomic implications, since, from adolescence to adulthood 80e85% of people suffer from this ailment in the modern world, therefore its effective management is essential (Khan and Siddiqui, 2005; Bellew et al., 2010). In order to make effective treatment available, there needs to be detailed understanding of biomechanical changes that may be contributing to LBP. This quest for adequate information has led to research on these biomechanical changes, with current literature indicating decreased changes in hip and lumbar motion range and velocity during the dynamic movement of forward bending (FB) (Norris and Matthews, 2006). FB, a common task of daily living resulting from coordinated activity between the back extensor muscles (erector spinae) and the hip extensor muscles (glutei and hamstrings), is a coupled movement combining lumbar flexion and pelvic rotation, and is termed lumbarepelvic rhythm (Norris and Matthews, 2006), Due to the location of the hamstring muscles with their origin at the ischial tuberosities, poor hamstring flexibility may restrict anterior pelvic rotation and in turn limit FB range unless compensated for by an increase in lumbar flexion, and consequent large amount of lumbar flexion on a repeated basis and resultant LBP (Esola et al., 1996). Based on these biomechanical concepts, FB has been implicated as a possible cause of LBP, thus suggesting that a relationship exists between hamstring muscle length (HML) and pelvic tilt range (PTR) (Mohamed et al., 2002; Kendall et al., 2005). In clinical practice, testing hamstring muscle length is advocated during assessments of patients with LBP (Petty and Moore, 2000) with an argument suggesting that lengthening the hamstrings may allow greater motion to occur at the hips and therefore reduce stress on the lumbar spine, though a causal relationship between hamstring flexibility and pelvic rotation has not been fully established
247 (Bellew et al., 2010). However, Norris and Matthews (2006) have stated that hamstring tightness is not related to pelvic tilt position during the static standing posture. There is however sparse data available on the relationship between hamstring length and pelvic tilt during dynamic posture. Influences on static posture are multi-factorial with the pull of the hamstrings being balanced by both the hip flexors and the abdominal muscles, but the dynamic movement of FB has not been thoroughly investigated (Norris and Matthews, 2006) most especially in people with low back pain. With previous researches suggesting that no relationship between HML and PTR exists during static standing (Nourbakhsh and Arab, 2002; Congdon et al., 2005) and very little being known about the dynamic movement of FB, the objectives of this study were therefore to compare both HML and PTR in individuals with and without LBP and investigate the relationships between HML and PTR in either group during dynamic movement of FB.
Methodology Procedure This Ex-post facto study involved 30 individuals with mechanical low back pain who were purposively recruited from the Physiotherapy Departments of University College Hospital, Ibadan and Adeoyo State Hospital, Ibadan and 30 height and weight-matched individuals without LBP who were mainly staff and students of the University of Ibadan. Ethical approval for the study was obtained from the University of Ibadan/University College Hospital Ethics Review Committee and informed consent was obtained from all the participants after detailed explanation of the nature and purpose of the study by researcher and assurance on the confidentiality of the data obtained.
Measurement The participants’ weight and height were measured using standard methods by the International Society for Advancement of Kinanthropometry (ISAK, 2001) and recorded. Other measurements were taken using the following procedure. 1. Hamstring Muscle Length: Hamstring muscle length was measured using the self-monitored active knee extension (AKE) test (Norris and Matthews, 2006). The participants were asked to lie supine on a plinth and flex their right knee and hip to 90 . Maintaining the position of the femur with their right hand, participants were instructed not to allow the femur to move away from the hand at any point during the test. The arms of the goniometer were aligned along the femur and fibula with its centre or axis placed over the lateral knee joint line. The participants were then instructed to extend their right leg as far as possible while keeping the foot relaxed. The end position was held for 5 s, and the angle of knee extension was read off the goniometer and recorded as HML (Norris and Matthews, 2006). 2. Pelvic Tilt Range: Participant’s pelvic tilt was assessed using the procedure described by Norris and Matthews
248
F.O. Fasuyi et al.
(2006). Before testing the forward bending action, the right tibia length was measured for each participant from the lateral joint line of the knee to the inferior border of the lateral malleolus. This length was designated ‘T’. A horizontal line was then drawn to join the posterior superior iliac spines and designated ‘L’. A line was also drawn on the ground and participants stood barefooted with their feet shoulder width apart, and the backs of the heels placed on the line. A bar was positioned at distance ‘T’ from the ground line and at a height ‘T’ from the line on the ground, and held in place on a frame. An inclinometer was placed over the participants’ sacrum with its upper edge aligned with the previously drawn line ‘L’ joining the participant’s posterior superior iliac spines. The digital inclinometer was then pressed firmly against the body to make and maintain contact with the spines of the sacral vertebra through the skin. The inclinometer read zero in the starting position and participants were instructed to bend forward to touch the bar in a single smooth action, without allowing any change in the angles of their knee joints. The inclinometer reading was taken immediately, and recorded as the PTR.
Statistical analysis ShapiroeWilk test indicated that the data were normally distributed hence data were analysed using parametric statistics. Participants’ age, height, weight, HML and PTR were summarized using range, mean and standard deviation. Both HML and PTR of the LBP and no LBP groups were compared using independent t-test while the correlations between HML and PTR were explored using Pearson Product Moment Correlation at 0.05 alpha level. All statistical analyses were performed with the SPSS 16.0 evaluation software (SPSS Inc., 1989e2007, Chicago, USA).
Results Both groups had even distributions of male and female participants. Participants in the LBP group were aged 35e70 years (mean Z 53.70 8.62 years while those in the without LBP group were aged 20e41 years (mean Z 26.07 5.70 years). The LBP group was significantly older than the control group but the groups did not Table 1
differ significantly in their weight and height. The group without LBP had significantly longer (p Z 0.01) HML than the group with LBP but the groups were not significantly different in their PTR (Table 1). The negative correlations between HML and PTR in both the group with (r Z 0.07) and without (r Z 0.02) LBP were not significant.
Discussion The main purpose of this study was to compare each of HML and PTR in individuals with and without LBP and investigate the relationship between HML and PTR in these two groups during dynamic movement of FB. Individuals without LBP had significantly greater hamstring flexibility (HML) than individuals with LBP. This finding is in agreement with what previous studies have reported and could be the reason for the larger variability in pelvic tilt range (PTR) found in the group of individuals with LBP as demonstrated in this study though, the two groups were not significantly different in their PTR. There has been a suggestion in the past that, variability in PTR could be a compensatory mechanism secondary to pelvic instability since it is a common finding in patients with LBP (van Wingerden et al., 1997; Nourbakhsh and Arab, 2002). However, in view of the documented effect of age and aging on flexibility of muscles and the fact that the LBP group had significantly lesser flexibility than the group without LBP, age could be a very important confounding factor in this study. The HML obtained for individuals without LBP in this study compared well with values reported from other studies in which the participants were of similarly young and active age (Rolls and George, 2004: Norris and Matthews, 2006) as against LBP group, who were relatively older individuals recruited from hospitals. Scores from the active knee extension (AKE) test indicated that the total range of motion for the leg excursion was reduced in individuals with LBP probably as a result of the relative isolated stretching of the hamstring during hip flexion movement without significant additional assistance from either lumbar lordosis or posterior pelvic tilting when the thigh is supported actively at 90 of hip flexion. This reduced flexibility may then be explained by greater hamstring muscle tightness during the normal range of motion (20 e50 ) (Marshall et al., 2009). It must however be noted that the tightness of the hamstrings is not only peculiar to the LBP group since the increase stiffness during the normal range of motion and decrease extensibility are
Physical characteristics of participants. With LBP (n Z 30) M S.D
Age Weight (kg) Height (m) HML ( ) PTR ( )
53.70 66.83 1.66 142.10 16.20
8.62 9.50 0.08 8.85 18.47
* Z significant difference at a Z 0.05. HML Z degrees. PTR Z degrees.
Without LBP (n Z 30) Range
M S.D
35e70 51e94 1.50e1.88 123e157 29e42
26.07 69.50 1.69 147.67 9.00
p-value Range
5.70 6.50 0.05 7.64 14.96
20e41 52e83 1.54e1.77 133e163 21e30
0.00* 0.21 0.11 0.01* 0.10
Hamstring muscle length and pelvic tilt range consistent findings among all individuals (Marshall et al., 2009). This finding might have been due to the adaptation that has taken place in the passive component of the muscles over time with resultant tightness and shortness as reflected in the reading of the goniometer during the AKE test. It can then be argued that the inability of the individuals with LBP to endure the stretch resulted in the termination of movement (Halbertsma et al., 2001). This stretch tolerance may also explain the reduced HML observed among participants in this study since this may be an actual mechanical restriction within the muscle caused by increased passive stiffness and not volitional choice (Marshall et al., 2009). Norris and Matthews (2006) found no significant association between HML and PTR during forward bending among individuals who were asymptomatic of LBP though they suggested the possibility of such association in patients with LBP. Although individuals with LBP were included in this study, no significant association was also observed between HML and PTR in both the LBP and no LBP groups. Our finding concerning however conforms with that of McClure et al. (1997) of a significant difference between the hamstring muscle flexibility of symptomatic and asymptomatic individuals while the hamstring muscle length did not correlate with measures of lumbopelvic kinematics. Similarly, Halbertsma et al. (2001) found that lumbar lordosis was not different between symptomatic and symptomatic individuals, though there was a difference between their HML. Further, Nourbakhsh and Arab (2002) did not find significant relationships between HML and both pelvic tilt and lumbar lordosis. Bellew et al. (2010) however reported that hamstring extensibility strongly correlated with pelvic rotation during maximal trunk flexion in a study that involved 20 asymptomatic subjects who performed forward bending in a toe touch motion with the total range measured as the distance from the middle finger to the floor. The limited flexion movement of FB restricted to tibia tuberosities in this study may explain the reason for the difference in result. Differences in HML measurement methods employed in the different studies could have also contributed to the differences in the findings reported. Video analysis provides an accurate method of measuring pelvic motion. However, although the method has been reported to be presently available even to students in developed countries, it is hardly available to even researchers in developing countries like Nigeria. The inclinometer used in this study is however a reliable method for assessing pelvic motion in the clinical setting (Bierma-Zeinstra et al., 2001). This study is also trying to draw attention of therapist in Nigeria to this method of assessment as a baseline for lumbopelvic exercise prescription since this instrument is cheaply accessible for their use. The long held impression that tight hamstring muscle limits anterior pelvic tilt because the hamstrings attaches to the ischial tuberosity which moves superiorly as the pelvis tilts, so that the distance between the attachments of the hamstrings is increased may not be correct after all. This is because the line of action of the hamstring being almost vertical and its attachment just slightly posterior to the femoral head provides a minimal force that posteriorly rotates the pelvis to counterbalance the activities of the
249 hip flexor and keep the pelvic orientation in check. Possible limitations to findings from our study are the significant difference between the ages of the groups with and without LBP as well as our failure to categorize participants in the LBP group using more defining diagnostic criteria. Findings from this study should hence be considered along with these limitations which future studies must accommodate.
Clinical implication Changes in the length of the hamstring muscle do not necessarily have an effect on pelvic tilt in both individuals with and without LBP. Reduced hamstring muscle length has been implicated as the cause or consequence of LBP. A finding of reduced hamstring muscle length in individuals with LBP in this study is hence in line with this consensus. The practice of screening for hamstring flexibility in individuals with mechanical low back pain and prescribing stretching exercises for those with reduced hamstring muscle length is hence justified.
Conclusion We conclude that no significant relationship exists between hamstring muscle length and pelvic tilt range during forward bending in both individuals with and without low back pain. These indicate that changes in HML may not necessarily affect pelvic rotation. Participants with LBP had significantly shorter hamstring muscle length than participants without LBP but the two groups did not differ significantly in their pelvic tilt range. The significant difference between the ages of the two groups is however a possible confounding factor hence our finding should be considered with caution.
Acknowledgments The authors acknowledge the heads Department of Physiotherapy, University College Hospital, Ibadan and Department of Physiotherapy, Adeoyo State Hospital, Ibadan for their support and cooperation during data collection. We also wish to appreciate all participants in this study. We wish to report no conflict of interest and declare that we are solely responsible for the content and writing of the manuscript.
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