Relation of Anterior Pelvic Tilt During Running to Clinical and Kinematic

Br J Sports Med 2000;34:279–283 279

Relation of anterior pelvic tilt during running to Br J Sports Med: first published as 10.1136/bjsm.34.4.279 on 1 August 2000. Downloaded from clinical and kinematic measures of hip extension

Anthony G Schache, Peter D Blanch, Anna T Murphy

Abstract position of the pelvis is associated with an Background—Limited hip extension flex- increase in the degree of lumbar lordosis ibility due to tight hip flexor musculature during running.78 The resulting repetitive or anterior hip capsular and ligamentous impingement of the vertebral facets from the structures is a possible cause of increased hyperextension of the lumbar spine is then anterior tilt of the pelvis during running. thought to be related to the onset of low back However, to date, research exploring this pain in runners.89 relation, as well as the kinematic relation Tightness of the hip flexor musculature—for between anterior tilt of the pelvis and peak example, iliopsoas, tensor fascia lata, rectus hip extension range of motion during run- femoris—hip joint capsule, or surrounding ning, is not available. anterior hip ligamentous and fascial structures Objective—To assess the relation of ante- in runners may reduce hip extension flexibility. rior pelvic tilt during running to peak hip This is commonly assessed clinically using the extension range of motion measured dur- Thomas test (or modifications of it). Limited ing running and hip extension flexibility hip extension flexibility has been proposed as measured clinically. one possible cause of increased anterior pelvic Methods—Hip extension flexibility was tilt and lumbar lordosis during running.5–7 assessed using the Thomas test, and the Given the proposed implications of increased three dimensional kinematic motion of the anterior pelvic tilt and lumbar lordosis during pelvis and hips were recorded using a running, it would be of interest to explore the VICON motion analysis system with 14 relation between hip extension flexibility and elite athletes running on a treadmill at 20 dynamic measures of anterior pelvic tilt and km/h. peak hip extension range of motion (ROM) Results—Anterior pelvic tilt displayed a during running. Published research into the significant (p<0.01) correlation with peak relations between these three variables is not hip extension range of motion during run- currently available. Therefore the purpose of ning. Anterior pelvic tilt tended to be this research project was to assess the relation increased in runners who displayed re- of anterior pelvic tilt during running to peak duced absolute peak hip extension range hip extension ROM measured during running of motion during terminal stance. No sig- and hip extension flexibility measured clini- http://bjsm.bmj.com/ nificant correlation was shown for hip cally. School of extension flexibility with either anterior pelvic tilt or peak hip extension range of Physiotherapy, Methods motion during running. University of Fourteen (10 male, 4 female) elite track and Melbourne, Conclusions—The outcomes of this study Melbourne, Australia field athletes, who were not suVering from any indicate that anterior pelvic tilt and hip musculoskeletal injuries, volunteered as sub- A G Schache extension are coordinated movements

jects for this study. All were experienced tread- on October 2, 2021 by guest. Protected copyright. Physiotherapy during running. Static hip extension flex- mill runners. They had a mean age of 23.6 Department, ibility measured using the modified Tho- years (range 18–29 years). Male subjects had a Australian Institute of mas test does not appear to be reflective of mean height of 177.1 cm (range 167.4–192.0 Sport, Canberra, ACT, these dynamic movements. cm), and female subjects had a mean height of Australia (Br J Sports Med 2000;34:279–283) P D Blanch 167.8 cm (range 163.6–174.5 cm). The study Keywords: running; kinematics; pelvis; hip; flexibility was conducted in accordance with the guide- Paediatric and Child lines of the Australian Institute of Sport ethics Health/Human committee. Movement Studies Injuries to the lumbo-pelvic-hip complex Hip extension flexibility was measured using Departments, University of account for about 14% of all injuries sustained the Thomas test. For this test, each subject sat Queensland, Brisbane, by distance runners and sprinters of varying on the end of a plinth and rolled backwards on Qld, Australia levels of ability.1 Although at first this injury to the plinth while holding both knees to the A T Murphy rate appears quite low with respect to the knee chest. This position ensured that the pelvis was and lower leg, injuries to the lumbo-pelvic-hip posteriorly tilted and the lumbar spine flexed Correspondence to: Mr A G Schache, School of complex from a clinical point of view are often on the plinth. Tester one held one hip in maxi- Physiotherapy, University of quite debilitating and demand prolonged peri- mal flexion to maintain this pelvic position, Melbourne, 200 Berkeley St, ods of rehabilitation. This is evident from sev- while the limb to be measured was lowered Carlton, Victoria 3053, Australia eral case studies describing running injuries to towards the floor with the knee in a relaxed 2–4 email: a.schache@ this region. One factor that has been anecdo- position. The head and shoulders of each sub- pgrad.unimelb.edu.au tally linked to running related injuries of the ject remained in a flat position on the plinth Accepted for publication lumbo-pelvic-hip complex is increased anterior throughout the test. Tester two used a goniom- 29 February 2000 pelvic tilt.56 It has been suggested that such a eter with a spirit level attached to the arm to

www.bjsportmed.com 280 Schache, Blanch, Murphy Br J Sports Med: first published as 10.1136/bjsm.34.4.279 on 1 August 2000. Downloaded from PSIS ASIS Horizontal Anterior pelvic tilt (+ve) Hip extension

Hip flexion

Hip extension angle (–ve)

Figure 1 Measurement of hip extension flexibility using the Thomas test. measure the angle formed between a horizontal reference line and a line connecting the greater Figure 2 Diagrammatic representation of the trochanter to the lateral femoral epicondyle (fig measurement of anterior pelvic tilt and peak hip extension range of motion during running. PSIS, posterior superior 1). A positive value was assigned to the iliac spine; ASIS, anterior superior iliac spine. situation where the thigh was extended below the horizontal reference line. This test has been Table 1 Group means and ranges for measured variables previously found to be adequately reliable Variable Mean Range when measuring normal subjects.10 All running sessions were performed on a Anterior pelvic tilt (°) 22.1 13.6–37.0 Peak hip extension ROM (°) −11.7 −27.1–7.5 treadmill (Sportech Gymnasium and Elec- Hip extension flexibility (°) 17.4 7.5–25.0 tronic Sports Equipment, Jamison, ACT, Aus- Relative stride length (%) 206.3 186.8–216.4 tralia) custom made for the Australian Institute Relative leg length (%) 53.5 51.1–56.1 of Sport biomechanics laboratory. The tread- ROM, range of motion. mill was set with no incline. To measure the motion of the pelvis and hips during running, tem (rotation occurring in the sagittal plane of small reflective markers were positioned on the global coordinate system). Hip flexion and both anterior superior iliac spines, the mid- extension was defined as a rotation of the thigh point between the two posterior superior iliac segment about the medial-lateral axis of the spines and both lateral femoral condyles. In local coordinate system in the pelvic segment addition, two markers mounted on small (rotation in the sagittal plane of the pelvic wands were positioned on the lateral aspect of coordinate system). Anterior pelvic tilt was the distal third of the right and left thighs on a assigned a positive value, and true hip joint line connecting the lateral projection of the hip extension was assigned a negative value in this

joint centre (greater trochanter) to the lateral study. http://bjsm.bmj.com/ projection of the knee joint centre (lateral femoral condyle). All markers were positioned DATA ANALYSIS according to the VICON Clinical Manager Anterior pelvic tilt was measured as the angle (Oxford Metrics Ltd, Oxford, UK) protocol. of the pelvis at the time of terminal hip exten- Each subject performed a ﬁve minute warm sion. The magnitude of terminal hip extension up running on the treadmill at the test speed of was used to represent peak hip extension 20 km/h. After this period, the three dimen- ROM. Stride time, based on the information

sional trajectories of the markers were collected from the load cell, represented the time on October 2, 2021 by guest. Protected copyright. using a VICON motion analysis system between two foot strikes on the same side of the (Oxford Metrics Ltd) with six cameras (NAC body. Stride length was calculated by multiply- Inc, Yokohama, Japan) operating at a sampling ing the known stride time by the belt speed of rate of 200 Hz. Foot strike and foot oV were the treadmill. Relative stride length and relative detected using a load cell (Applied Measure- leg length for each subject were then obtained ment Australia Pty Ltd, Jamison, ACT, Aus- by expressing the values as a percentage of the tralia) attached to the treadmill. respective height. Immediately after the five minute warm up, Data for the left and right sides were five seconds of data were captured for each compared using a two tailed paired t test. For subject, and a single representative cycle was each subject, data for the left and right sides chosen for analysis. The three dimensional were combined, and average values were used angular rotations of the pelvis and hips were in analyses. Means and ranges were calculated computed using a technique equivalent to the for each of the variables. Simple and multiple geometrical conventions described by Grood regression analyses were used to assess the and Suntay.11 Pelvic motion was measured as a relations between all of the variables. rotation of the pelvic segment with respect to a global coordinate system (laboratory). Hip Results motion was measured as a rotation of the thigh Individual t tests showed no significant diVer- segment with respect to the pelvic segment (fig ences between the left and right sides for any of 2). More specifically, pelvic tilt was defined as a the variables (p>0.05). Therefore the use of rotation of the pelvic segment about the average values of the left and right side for each medial-lateral axis of the global coordinate sys- subject was considered appropriate. Table 1

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Table 2 Regression analysis results ROM respectively compare favourably with three dimensional graphical data of running Anterior Peak hip 12 pelvic tilt extension ROM Hip extension Relative stride Relative leg reported by Novacheck. The average hip (APT) (HEROM) flexibility (HEF) length (RSL) length (RLL) extension flexibility value of 17.4° is also simi- 13 APT — **y = 0.6x + 30 y = −0.05x + 23 y = −0.2x + 68 y = 1.9x − 77 lar to the results of Harvey, who found a mean HEROM 0.8** — y = −0.1x − 10 y = −0.4x + 63 *y = 3.7x − 209 value of 14° for a group of runners. HEF 0.002 0.004 — y = 0.07x + 3 y = 0.1x + 10 Anterior pelvic tilt was found to be related to RSL 0.08 0.12 0.01 — y = −1x + 271 RLL 0.15 0.31* 0.001 0.04 — peak hip extension ROM during running (fig 3). Figure 3 shows the increasing pelvic tilt Shaded numbers are the R2 values and the rest are the regression equations. angle in subjects with reduced absolute peak *Significant result at p<0.05; **significant result at p<0.01. hip extension ROM. Figures 4 and 5 show the 40 sagittal plane movements of the pelvis and hips over a running cycle for the subject displaying the greatest degree of absolute peak hip exten- 35 sion ROM (fig 4) and the subject displaying the smallest degree of absolute peak hip extension 30 ROM (fig 5). On comparison of figs 4 and 5, the anterior pelvic tilt angle can be seen to dif- fer by about 20° between the two subjects. A 25 significant positive correlation between anterior pelvic tilt and peak hip extension ROM has 14 20 also been found by Lee and coworkers, who Anterior pelvic tilt investigated the walking pattern of 41 neurological patients with bilateral hip flexion 15 contractures. When viewing figs 3–5 it is apparent that the sagittal plane movement patterns of the pelvis 10 –30 –20 –10 0 10 and hips diVer across a group of subjects run- Hip extension Hip flexion ning at the same speed. Wilson and 15 16 Peak hip extension ROM coworkers, when investigating the kinematic behaviour of the knee, showed that the Figure 3 Anterior pelvic tilt versus peak hip extension joint followed a unique path of least resistance range of motion (ROM) in the 14 subjects. Both variables are reported in degrees. that was determined by the geometrical configurations of the joint surface and sur- shows the group means and ranges for each rounding anatomical structures. This led Nigg measurement, and table 2 the results from the and coworkers17 to propose that the skeleton simple regression analysis. has a preferred path for a given movement Anterior pelvic tilt was found to have a task—for example, running. Based on this, the significant (p<0.01) positive correlation with diVering sagittal plane movement patterns of

peak hip extension ROM during running. This the pelvis and hips displayed in this study may http://bjsm.bmj.com/ meant that anterior pelvic tilt tended to be be explained on the basis of individual increased in runners who displayed reduced variations in the preferred paths of motion of absolute peak hip extension ROM during the involved joints. Some subjects displayed a terminal stance (ﬁg 3). Peak hip extension preferred path during terminal stance that ROM was found to have a weak but statistically involved predominantly hip extension, whereas signiﬁcant (p<0.05) positive correlation with others displayed a preferred path that involved relative leg length. Subjects with increased increased anterior pelvic tilt with less hip

relative leg lengths tended to run with reduced extension. As the subjects were all running at on October 2, 2021 by guest. Protected copyright. absolute peak hip extension ROM. No signifi- the same velocity, the diVerences between the cant correlation was found between anterior various paths in terms of forward momentum pelvic tilt and hip extension flexibility. Also, no may be minimal. For example, the thigh significant correlation was found between peak segment measured with respect to the global hip extension ROM during running and hip coordinate system may well be similar for extension flexibility. diVerent paths. The question that is of vital A stepwise multiple regression was per- importance is whether a particular path is formed as an additional analysis in which ante- related to injury. The anecdotal literature to rior pelvic tilt was the dependent variable and date suggests that increased anterior pelvic tilt peak hip extension ROM, hip extension during running is related to injury.56 Further flexibility, relative stride length, and relative leg research is required to support or negate these length were the independent variables. The hypotheses. equation with maximal prediction accuracy It has been reported that anatomical features using the least amount of independent vari- may actually provide the limit to hip extension ables contained only peak hip extension ROM, during running, as maximal values appear to as hip extension flexibility, relative stride approach the limit for passive range.18 From a length, and relative leg length were all found to clinical point of view, it would seem logical that make insignificant contributions. the flexibility of the soft tissue structures anterior to the hip is a factor that determines the Discussion preferred path of motion—that is, a relation The average values of 22.1° and −11.7° for between peak hip extension ROM and hip anterior pelvic tilt and peak hip extension extension flexibility exists. However, hip exten-

www.bjsportmed.com 282 Schache, Blanch, Murphy

Foot strike Toe off advised that clinicians need to be extremely Br J Sports Med: first published as 10.1136/bjsm.34.4.279 on 1 August 2000. Downloaded from 80 cautious about making predictions about the Anterior pelvic tilt Pelvis dynamic sagittal plane movements of the pelvis 70 Hip and hips based on the outcomes of the Thomas Hip flexion test. 60 There are several possible explanations as to 50 why the Thomas test measure was not found to relate to the dynamic measures. It may be that 40 static ﬂexibility is not the major factor govern- ing the degree of anterior pelvic tilt or peak hip 30 extension ROM when running at a submaxi- mal speed. Such variables may be determined 20

Degrees by complex dynamic neuromotor patterns 10 rather than static ﬂexibility alone. It is feasible that static soft tissue restraints only become a 0 factor at maximal speeds of running. Further research is required to answer this question. Posterior pelvic tilt –10 There are also diVerences with regard to the position of the pelvis and the external forces –20 Hip extension acting about the hip joints between the two situations. Future researchers might consider –30 0 25 50 75 100 modifying the Thomas test to replicate the % running cycle position of the pelvis during running. Figure 4 Sagittal plane pelvis and hip angles over the running cycle for the subject Other clinical tests that relate to anterior displaying the greatest degree of peak hip extension range of motion. pelvic tilt and peak hip extension ROM during running need to be investigated. For example, Pelvis Ounpuu and coworkers19 measured 44 patients Foot strike Toe off Hip with cerebral palsy, and found a high positive 80 correlation between pelvic position in the Anterior pelvic tilt sagittal plane during standing and dynamic 70 measures of pelvic tilt during walking. Clinical Hip flexion 60 measures of the pelvic tilt angle in standing are easy to perform and have certainly been shown 50 to be reliable and valid.22–24 If it could be shown that relations between pelvic tilt in standing 40 and dynamic measures of anterior pelvic tilt and peak hip extension ROM during running 30 exist, then the practitioner would have a simple 20 test that is reﬂective of the dynamic sagittal Degrees plane movements of the pelvis and hips. The http://bjsm.bmj.com/ 10 ultimate clinical relevance of this test though depends on whether a particular dynamic sag- 0 ittal plane movement pattern of the pelvis and hips is shown to be related to injury. Posterior pelvic tilt –10 Peak hip extension ROM was found to have –20 a positive correlation with relative leg length. Hip extension This meant that subjects with increased relative

–30 leg lengths tended to run with reduced peak on October 2, 2021 by guest. Protected copyright. 0 25 50 75 100 hip extension ROM. This may well be a prod- % running cycle uct of having diVerent sized people running at Figure 5 Sagittal plane pelvis and hip angles over the running cycle for the subject the same absolute velocity on a treadmill. Sub- displaying the smallest degree of peak hip extension range of motion. jects with longer relative leg lengths had longer sion flexibility, measured using the Thomas levers to run with and therefore required less test described in this study, was not found to be peak hip extension ROM than those with smaller relative leg lengths. One may also indicative of the dynamic measures of peak hip expect subjects in this study with longer relative extension ROM or anterior pelvic tilt. leg lengths to run with smaller relative strides; The results of this study compare favourably however, a correlation between relative leg with the work of others. Several 14 19 20 length and relative stride length was not found. researchers have reported similar findings The relatively small sample size must be in studies investigating the kinematic pattern of taken into account when reviewing the results the pelvis and hips during walking in patients of this study. Also, the findings relate specifi- with varying degrees of hip flexion contrac- cally to treadmill running at 20 km/h and the 21 tures. In addition, Bar-On and coworkers technique used to assess hip extension flexibil- measured the degree of hip flexion contracture ity. Future research is required to establish using the Thomas test on 51 subjects with whether similar results would be obtained in a neurological deficits and found no correlation larger population running overground at diVer- with radiologically determined measures on ent speeds. the same subjects. As a result of the findings In conclusion, anterior pelvic tilt and hip from this study and the work of others, it is extension appear to be coordinated movements

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11 Grood ES, Suntay WJ. A joint coordinate system for the during the running action. Static hip extension Br J Sports Med: first published as 10.1136/bjsm.34.4.279 on 1 August 2000. Downloaded from clinical description of three-dimensional motions: applica- flexibility, measured using the Thomas test, tion to the knee. J Biomech Eng 1983;105:136–44. was not found to be reflective of these dynamic 12 Novacheck TF. The biomechanics of running. Gait and Pos- movements. The ability for clinicians to ture 1998;7:77–95. 13 Harvey D. Assesment of the flexibility of elite athletes using interpret the results of the Thomas test with the modified Thomas test. Br J Sports Med 1998;32:68–70. regard to the sagittal plane movement patterns 14 Lee LW, Kerrigan DC, Della Croce U. Dynamic implications of hip flexion contractures. Am J Phys Med Rehabil of the pelvis and hips during running may 1997;76:502–8. therefore be limited. 15 Wilson DR, Feikes AB, Zavatsky AB, et al. The one degree- of-freedom nature of the human knee joint. Basis for a kinematic model. In: HoVer JA, Chapman A, Eng JJ, et al,eds. This project was funded by a grant from the Australian Olympic Proceedings of the Ninth Biennial Conference of the Canadian Athlete Program. The research was performed while AGSand Society for Biomechanics. Vancouver: Conference Organizing ATMwereworking in the physiotherapy and biomechanics Committee, 1996:194–5. departments respectively at the Australian Institute of Sport. 16 Wilson DR, Feikes JD, O’Connor JJ. Ligaments and articu- lar contact guide passive knee flexion. J Biomech 1998;31: 1 Bennell KL, Crossley K. Musculoskeletal injuries in track 1127–36. and field: incidence, distribution and risk factors. Aust J Sci 17 Nigg BM, Nurse MA, Stefanyshyn DJ. Shoe inserts and Med Sport 1996;28:69–75. orthotics for sport and physical activities. Med Sci Sports 2 Koch RA, Jackson DW. Pubic symphysitis in runners: a Exerc 1999;31:S421–8. report of two cases. Am J Sports Med 1981;9:62–3. 18 Williams KR. Biomechanics of running. Exerc Sport Sci Rev 3 Fields KB, Kramer JS, Delaney MJ. Osteitis pubis and pel- 1985;13:389–441. vic stress fracture in an elite female distance runner. Clin 19 Ounpuu S, Davis RB, Walsh JHP, et al. Sagittal plane pelvic Sports Med 1990;2:173–8. 4 Rold JF, Rold BA. Pubic stress symphysitis in a female dis- motion: relationship to standing pelvic position and clinical tance runner. Physician and Sports Medicine 1986;14:61–5. measures. Dev Med Child Neurol 1995;37:25. 5 Geraci MCJr. Overuse injuries of the hip and pelvis. Journal 20 DeLuca PA, Ounpuu S, Davis RB, et al.EVect of hamstring of Back and Musculoskeletal Rehabilitation 1996;6:5–19. and psoas lengthening on pelvic tilt in patients with spastic 6 Klein KK, Roberts CA. Mechanical problems of maratho- diplegic cerebral palsy. J Pediatr Orthop 1998;18:712–18. ners and joggers: cause and solution. American Corrective 21 Bar-On E, Malkin C, Eilert RE, et al. Hip flexion Therapy Journal 1976;30:187–91. contracture in cerebral palsy. The association between 7 Bach DK, Green DS, Jensen GM, et al. A comparison of clinical and radiological measurement methods. Clin muscular tightness in runners and nonrunners and the Orthop 1992;281:97–100. relation of muscular tightness to low back pain in runners. 22 Alviso DJ, Dong GT, Lentell GL. Intertester reliability for J Orthop Sports Phys Ther 1985;6:315–23. measuring pelvic tilt in standing. Phys Ther 1988;68:1347– 8 Slocum DB, James SL. Biomechanics of running. JAMA 51. 1968;205:721–8. 9 Jackson DW, Sutker AN. Low back problems in runners. In: 23 Cromwell RD, Cummings GS, Walker JR, et al. Intratester Mack RP, ed. American Academy of Orthopaedic Surgeons and intertester reliability and validity of measures of symposium on the foot and leg in running sports. St Louis: CV innominate bone inclination. J Orthop Sports Phys Ther Mosby Co, 1982:123–34. 1994;20:88–97. 10 Bartlett MD, Wolf LS, ShurtleV DB, et al. Hip flexion 24 Gajdosik R, Simpson R, Smith R, et al. Pelvic tilt. Intratester contractures: a comparison of measurement methods. Arch reliability of measuring the standing position and range of Phys Med Rehabil 1985;66:620–5. motion. Phys Ther 1985;65:169–74.

Take home message Anterior pelvic tilt and hip extension are coordinated movements during running. Static hip extension ﬂexibility does not appear to be reﬂective of these dynamic movements. Clinicians must therefore be cautious about making predictions about the sagittal plane movements of the pelvis and hips during running based on the results of the Thomas test. http://bjsm.bmj.com/ on October 2, 2021 by guest. Protected copyright.