Lombopelvic kinematic characteristics of golfers with limited hip rotation.

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Lumbopelvic Kinematic Characteristics of Golfers With Limited Hip Rotation Sol-Bi Kim, Joshua (Sung) H. You, Oh-Yun Kwon and Chung-Hwi Yi Am J Sports Med published online November 14, 2014 DOI: 10.1177/0363546514555698 The online version of this article can be found at: http://ajs.sagepub.com/content/early/2014/11/13/0363546514555698

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Lumbopelvic Kinematic Characteristics of Golfers With Limited Hip Rotation Sol-Bi Kim,*y MS, Joshua (Sung) H. You,yz§ PhD, Oh-Yun Kwon,y§ PhD, and Chung-Hwi Yi,y§ PhD Investigation performed at Yonsei University, Wonju, Republic of Korea Background: While the biomechanical characteristics of the golf swing are well established, the lumbopelvic kinematic characteristics of professional golfers with limited hip internal rotation warrant further investigation.

Purpose: The specific aim was to ascertain mechanical differences in lumbopelvic-hip movement of asymptomatic professional golfers with and without limited hip internal rotation during the golf swing.

Study Design: Controlled laboratory study.

Methods: Thirty professional male golfers (aged 25-35 years and 0 handicap matched) were classified into either the limited hip internal motion (LHIM) group (range of motion \20°) or the normal hip internal motion (NHIM) group (range of motion 30°). All participants underwent clinical tests (muscle strength, muscle length, and range of motion) and a biomechanical assessment using 8 infrared optic cameras in a motion analysis system. Independent t tests were performed to determine potential mean differences in muscle strength, length, and range of motion and lumbopelvic kinematics at P \ .05.

Results: Kinematic analysis revealed that the LHIM group showed significantly greater lumbar flexion (P \ .001), right and left axial rotation (P \ .025), and right-side lateral bending (P = .003) than the NHIM group. A greater pelvic posterior tilt was observed in the LHIM group when compared with the NHIM group (P = .021). Clinical tests showed reduced internal rotator muscle strength and shorter muscle length in the iliopsoas (P = .017) and hamstring (P \ .001) among those in the LHIM group when compared with the NHIM group.

Clinical Relevance: The study data suggest that constraints to hip joint internal rotation, along with muscle strength imbalances between the agonist and antagonist muscles and muscle tightness, are associated with substantially greater lumbopelvic movement during the golf swing.

Keywords: golf; limited hip rotation; lumbopelvic kinematics; muscle imbalance

Limited hip joint mobility is an important biomechanical marker of low back pain (LBP) in golfers.24,36,54 Globally, LBP is a common occurrence in approximately 55 million golfers.12,25 Empirical evidence suggests that the biomechanics of LBP is characterized by limited hip joint mobility4,6,17,24,32,47,54 and associated imbalance in muscle strength and length.2,17,32,38-40,42,49 When compared with golfers without LBP, those with a history of LBP exhibit limited hip joint mobility during hip internal rotation of

the lead side (eg, left hip for a right-handed golfer) and lumbar extension.54 In fact, recent clinical evidence showed that improved internal rotation mobility along with lumbar stabilization exercises helped achieve painfree golf swings and performance.23,45 Biomechanically, limited hip joint mobility may interfere with the efficient transmission of kinetic energy from the lower extremities to the lumbopelvic kinetic chain, thereby causing excessive compensatory lumbar rotational stress during the golf swing.17,54 An understanding of the biomechanical relationship between angular displacements of the hip joint and peak rotational angles in the lumbar spine may thus render important clues for the biomechanics of golfers with LBP. Muscle imbalances in strength and length are recognized as important causes of limited hip joint mobility and associated movement impairment.7,15,49,54 The term ‘‘muscle balance’’ was first coined by Janda20,21 and describes a relative equality in muscle strength between the agonist (eg, internal hip rotators) and antagonist (eg, external hip rotators) muscles.43 Decreased iliopsoas and hamstring muscle length or flexibility has also been shown to contribute to limited hip joint mobility and lumbopelvic

z

Address correspondence to Joshua (Sung) H. You, PhD, Department of Physical Therapy, College of Health Science, Yonsei University, Wonju, Republic of Korea (e-mail: neurorehab@yonsei.ac.kr). *Research and Development Team, Korea Orthopedics and Rehabilitation Engineering Center, Incheon, Republic of Korea. y Department of Ergonomic Therapy, Graduate School of Health and Environment, Yonsei University, Wonju, Republic of Korea. § Department of Physical Therapy, College of Health Science, Yonsei University, Wonju, Republic of Korea.

The authors declared that they have no conflicts of interest in the authorship and publication of this contribution.

The American Journal of Sports Medicine, Vol. XX, No. X DOI: 10.1177/0363546514555698 Ó 2014 The Author(s)

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TABLE 1 Demographic and Anthropometric Characteristics of NHIM and LHIM Groupsa Characteristics

LHIM Group

NHIM Group

Age, y Height, cm Mass, kg Length of golf career, y Maximum ball velocity, cm/s Right hip Peak IR PROM, deg Peak ER PROM, deg Left hip Peak IR PROM, deg Peak ER PROM, deg

29.0 178.1 78.8 13.3 438.8

31.0 178.6 76.6 12.3 423.9

6 6 6 6 6

4.9 6.1 12.6 2.4 58.69

6 6 6 6 6

4.5 9.3 14.6 2.3 63.81

P Value

95% CI

.135 .424 .331 .369 .276

— — — — —

28.6 6 2.1 40.1 6 8.8

29.7 6 3.2 41.6 6 7.0

.172 .301

— —

17.2 6 5.0 51.3 6 8.2

33.1 6 2.9 40.0 6 5.4

.000b .000b

14.27 to 17.69 –16.50 to –6.08

a Data are expressed as mean 6 SD. ER, external rotation; IR, internal rotation; LHIM, limited hip internal motion; NHIM, normal hip internal motion; PROM, passive range of motion. b Statistically significant difference.

movement control, causing excessive lumbar lordosis or excessive lumbar kyphosis, respectively, in patients with LBP.2,32,42 Asymmetrical hip extensor muscle strength in particular has been found to be closely associated with LBP in female athletes.39 Nadler et al38 demonstrated that in the face of hip abduction asymmetric weakness, increased muscular requirements of the lateral trunk stabilizers are necessary to better stabilize the pelvis. As well as muscle weakness, muscle length imbalance affects joint mobility. In addition, LBP has also been associated with decreased ranges of motion in hip internal rotation11 and extension.55 This altered length-tension relationship can cause limited hip mobility, thereby creating compensatory excessive lumbar motion where the least resistance or stiffness is found.17 However, the exact nature of the biomechanical characteristics underpinning the relationship between constrained hip joint movement and LBP disorders in golfers remains unknown.

To ascertain this premise, we examined biomechanical factors including the 3-dimensional joint kinematics of the lumbar spine, pelvis, and hip as well as muscle length and strength imbalance in the lumbopelvic-hip joint muscles in asymptomatic professional golfers with and without limited hip internal rotation. Our hypothesis was that different biomechanical characteristics in lumbopelvic-hip joint kinematics, muscle length, and muscle strength would exist between golfers with and without limited hip internal rotation.

MATERIALS AND METHODS

Institutional Review Board of Yonsei University approved the experimental protocol. All participants were righthanded golfers, meaning that the left hip was a leading hip and the right hip was a trailing hip. Of the 30 participants, 15 who demonstrated limited left hip internal rotation (passive range of motion \20°) were classified into the limited hip internal motion (LHIM) group. The other 15 participants demonstrated normal left hip internal rotation (passive range of motion 30°) and were classified into the normal hip internal motion (NHIM) group.48 The groups presented similar demographic and anthropometric characteristics (Table 1). Clinical measurements including routine physical screening of functional active mobility and pain, hip rotation passive range of motion,54 and the hip flexion–abduction–external rotation (FABER) test46 were performed to determine whether the participants met the inclusion or exclusion criteria. The inclusion criteria were (1) certified KPGA professional golfers and (2) experience of more than 9 years. The exclusion criteria were (1) positive response to the FABER test and (2) prior back or lower extremity surgery and current or ongoing musculoskeletal system inflammations (such as LBP, patellar tendinitis, plantar fasciitis, and Achilles tendinitis) that would affect the experimental tests.17,18 All golfers underwent clinical and biomechanical testing. Clinical tests entailed trunk and hip muscle strength as well as hamstring and iliopsoas flexibility tests. A biomechanical assessment included a kinematic analysis of the motion of their full golf swing. One investigator (S.-B.K.) collected all clinical data and was not blinded to the experiment.

Participants

Motion Analysis

Thirty male professional golfers participated in this study.

The participants were recruited through an online newsletter on the Korea Professional Golfers Association (KPGA) website between January 2012 and March 2012.

Each participant signed an informed consent form before participating in the study. The Human Ethics and

Three-dimensional motion analysis (Motion Analysis, Motion Analysis Corp) with 8 infrared cameras was used to determine the lumbar spine, pelvis, and hip joint angular kinematics during the golf swing. Helen Hayes fullbody marker sets were used with twenty-nine 12.5-mm reflective markers attached bilaterally to the following

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anatomic landmarks: heel, second metatarsal head, lateral and medial malleoli, tibial tuberosity, lateral and medial knee joints, anterior superior iliac spine, superior aspect of the L5-sacral interface, tip of the acromion process, lateral humeral epicondyle, proximal and distal radioulnar joints, front of head, rear of head, top of head, and inferior angle of the scapula.51,52 Additionally, to define the lumbar segment, 2 markers were secured with athletic tape to the first lumbar spinous process and the right side of the back at the T12-L1 level.25 One marker was also placed on the head of the golf club to identify the phases of the golf swing,10 and reflective tape was attached to the ball to define its velocity. Kinematic data during each golf swing motion were acquired at a frequency of 120 Hz.25 Before data collection, each participant was instructed to perform his typical warm-up. The participant was then asked to stand with 1 foot on each force plate in an anatomically appropriate position and execute 10 full golf swings by hitting an actual golf ball with a driver club off an artificial golf mat and into a curtain.

Clinical Tests Hip joint muscle flexibility was conceptually defined as an ability to lengthen the target muscle throughout the normal range of motion and was quantitatively determined by the following methods.1 Hamstring flexibility was measured by a digital goniometer (digital display goniometer SP-II, An Tai) during the passive straight-leg raise test.

The participant was positioned supine on a table with firm lumbar support. The pelvis was stabilized with a belt, and the opposite leg was fixed onto the table by a fixation belt. The ipsilateral hip was positioned in 90° of flexion and stabilized in this position by the examiner’s hand, keeping the hip in flexion. The examiner then passively extended the knee by regular force and measured the angle of the knee with the digital goniometer. Three trials were conducted. Iliopsoas flexibility was evaluated using the Thomas test.45 The participants were placed in a supine position on an examination table with their knees bent over the edge. They were instructed to flex 1 knee to the chest and hold it. The examiner then measured the angle between the tested thigh (opposite to the knee held to the chest) and the table.

Trunk muscle strength was measured using an isokinetic dynamometer (Biodex System III, Biodex Medical Systems Inc).25 Isokinetic strength during trunk flexion and extension was evaluated with each participant in a seated position. The participants performed 5 repetitions at 60 deg/s during trunk flexion and extension. Five trials were conducted, with a 1-minute resting period between each trial.

Hip rotator strength was tested with a handheld dynamometer (Power Track II Commander, JTECH Medical)27 and isokinetic dynamometer chair. The participants were seated in the chair and stabilized with multiple straps and a hip abduction wedge. Their hips and knees were flexed at 90° such that the hips were in a neutral position.

To assess the external hip rotators, the dynamometer was applied just proximal to the malleolus. The participants

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were asked to keep their arms held against the body with their hips positioned in slight external rotation with the medial malleolus aligned with the midline of the body.

The internal rotators were evaluated with the hips in neutral rotation, with resistance to movement applied just above the lateral malleolus. The duration of each maximal isometric contraction was standardized at 5 seconds. Three trials were performed, with a resting period of 30 seconds between each trial. Based on the measured muscle strength data, muscle imbalances between the trunk flexors and extensors as well as hip internal rotators and external rotators were determined by computing the ratio between agonist and antagonist muscle strength (N/kg).

Data Analysis and Statistics The measured kinematic coordinate data were analyzed using biomechanical analysis software (Cortex 1.3, Motion Analysis Corp). The kinematic coordinate data of the golf swing were smoothed by a Butterworth filter at 12 Hz.34 The selected kinematic angular displacement was calculated at 6 critical events during the golf swing: address, top of the backswing, acceleration,5 impact, followthrough,34 and finish. The kinematic data of the 5 highest ball velocities were analyzed and averaged for each participant.25 Descriptive statistics, including the means 6 SDs, were calculated. The results were analyzed using SPSS version 17.0 software (IBM Corp). Independent variables included the group factor. Dependent variables included angular displacement, muscle strength, and muscle length. A separate 2-tailed independent t test and a 1-sample Kolmogorov-Smirnov test were conducted to verify the differences in the general characteristics of the groups and to test the normality of the distribution, respectively. The Thomas test values did not demonstrate a normal distribution, and thus, a Mann-Whitney U test was performed to compare the differences in the Thomas test values between the 2 groups. The Pearson correlation test was used to analyze the correlation between maximum left rotation of the pelvis and passive range of motion of the hip. Statistical significance was defined as P \ .05.

RESULTS Range of Motion Data Passive hip rotation data are presented in Table 1. Participants in the LHIM group demonstrated significantly less hamstring flexibility in the right leg than those in the NHIM group (mean, 166.9° 6 5.3° vs 174.3° 6 2.7°, respectively; P \ .001). No statistically significant difference was observed in the left leg (mean, 170.6° 6 5.1° vs 170.4° 6 5.3°, respectively; P = .789). The Mann-Whitney U test revealed a greater increase in the right hip flexion angle in participants of the LHIM group when compared with those of the NHIM group (mean, 21.8° 6 10.1° vs 9.5° 6 10.9°, respectively; P = .017). No significant difference

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TABLE 2 Muscle Strength and Strength (Imbalance) Ratio of Lumbopelvic Musculature of NHIM and LHIM Groupsa Muscles Trunk strength Extensor, N m/kg Flexor, N m/kg Strength ratio (extensor/flexor) Right hip strength Internal rotator, N/kg External rotator, N/kg Ratio (external rotator/internal rotator) Left hip strength Internal rotator, N/kg External rotator, N/kg Ratio (external rotator/internal rotator)

LHIM Group

NHIM Group

P Value

95% CI

178.76 6 79.74 114.64 6 47.81 1.53 6 0.12

193.31 6 85.31 142.27 6 51.59 1.32 6 0.19

.633 .139 .946

— — —

1.22 6 0.16 0.94 6 0.14 0.77 6 0.17

1.22 6 0.12 1.09 6 0.20 0.89 6 0.12

.888 .025b .017b

— 0.02 to 0.28 0.02 to 0.20

1.01 6 0.13 1.14 6 0.19 1.12 6 0.16

1.23 6 0.18 1.18 6 0.15 0.96 6 0.16

.001b .620 .000b

0.10 to 0.34 — –0.30 to –0.02

a

Data are expressed as mean 6 SD. LHIM, limited hip internal motion; NHIM, normal hip internal motion.

Statistically significant difference.

b

was observed in the left leg between the groups (mean, 15.0° 6 14.0° vs 14.7° 6 12.8°, respectively; P = .471).

Muscle Strength and Imbalance Ratio Muscle strength and imbalance for the selected trunk and hip muscles are presented in Table 2. Right hip external rotator strength and left hip internal rotator strength were significantly lower in participants in the LHIM group when compared with those in the NHIM group. The left and right hip rotator muscle imbalance ratio (external rotator/internal rotator) was also significantly different between the 2 groups, with a muscle imbalance ratio of closer to 1, representing ‘‘normal muscle balance.’’41 The results also indicate a difference in muscle strength imbalance in the internal rotation and external rotation muscles between the groups. No statistically significant difference in trunk flexion, extension strength, or strength ratio (extensor/flexor) was identified.

compared with those of the NHIM group in the followthrough phase (P \ .001) and finish phase (P \ .001) of the golf swing cycle (Figure 2A). The anterior tilt of the pelvis was significantly smaller in participants of the LHIM group when compared with those of the NHIM group in the acceleration phase (P = .021). However, in the top of the backswing phase, the anterior tilt was larger in participants in the LHIM group than in those in the NHIM group (P = .041) (Figure 2B).

Participants in the LHIM group had a significantly less left hip internal rotation angle than those in the NHIM group in the finish phase (P = .004) (Figure 3A).

The Pearson correlation test revealed a positive relationship between left hip internal rotation passive range of motion and left pelvic rotation during the golf swing (r = 0.603, P \ .001). However, left hip external rotation passive range of motion was negatively correlated with left pelvic rotation (r = –0.441, P = .016).

DISCUSSION Kinematics Kinematics of lumbar joint segments during the golf swing is presented in Figure 1. Lumbar axial rotation was significantly higher in participants of the LHIM group when compared with those of the NHIM group in the top of the backswing phase (P \ .001), follow-through phase (P = .012), and finish phase (P = .020) of the golf swing cycle (Figure 1A). Lumbar right-side bending was also significantly increased in participants of the LHIM group relative to those of the NHIM group in the impact phase (P = .016) and finish phase (P = .003) (Figure 1B). Participants in the LHIM group showed significantly greater lumbar flexion angles than those in the NHIM group in the address (P \ .001), top of the backswing (P \ .001), acceleration (P \ .001), and impact (P \ .001) phases (Figure 1C).

Kinematics of pelvic movements during the golf swing is illustrated in Figure 2. Pelvic rotation was significantly decreased in participants of the LHIM group when

This investigation highlights the important biomechanical characteristics of lumbopelvic-hip movement in professional golfers with limited internal rotation of the left hip during the golf swing. As anticipated, we found that golfers with limited hip rotation showed greater lumbar rotation than the controls. Moreover, limited hip rotation was associated with imbalances in hip muscle strength (internal vs external rotators) and hamstring and iliopsoas flexibility (right vs left). Excessive lumbar rotation can alter coordination and control in lumbopelvic-hip movements during the golf swing, potentially leading to a higher risk of lumbar injuries in professional golfers.28,29 Normally, finishing the golf swing with extension, lateral bending on the right (trailing) side, and rotation of the trunk on the left (leading) side allow the golfer to efficiently absorb the energy released during the downswing in right-handed golfers.14,37 However, excessive motion of the spine may result in increased shear force on the

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Figure 2. Comparison of pelvis angular displacement during 6 golf swing events between the normal hip internal motion (NHIM) and limited hip internal motion (LHIM) groups: (A) transverse plane and (B) sagittal plane. Lt rot, left rotation; Rt rot, right rotation. The error bars represent 6SD. *P \ .05. ***P \ .001.

Figure 1. Comparison of lumbar angular displacement during 6 golf swing events between the normal hip internal motion (NHIM) and limited hip internal motion (LHIM) groups: (A) transverse plane, (B) coronal plane, and (C) sagittal plane.

Ext, extension; Flex, flexion; Lt, left; Lt rot, left rotation; Rt, right; Rt rot, right rotation. The error bars represent 6SD. *P \ .05. ***P \ .001. lumbar spine14 and soft tissue of the lumbar region.49 In this study, the normal kinetic link between the lumbopelvic-hip chain was compromised in golfers with limited hip internal rotation, who then had to increase their axial lumbar rotation to compensate for the altered kinetic chain.17 Over time, repetitive and excessive lumbar spinal rotation motion due to limited hip range of motion may lead to lumbar segmental instability (hypermobility),13,24,47 which may

further weaken the kinetic links within the lumbopelvic-hip chain system. Lumbar segmental hypermobility in a weakened lumbopelvic-hip kinetic chain imposes shear and compression loads on the lumbar spine and intervertebral joints, which may result in mechanical LBP11,17,32,33,49,54 associated with facet arthropathy and herniated discs.19,26,50,53 Recent clinical evidence showed a significant elimination of chronic LBP in golfers after an improvement in hip internal rotation, indicating that decreased or impaired hip range of motion contributes to increased rotation loading in patients with LBP.24 The appropriate flexibility of the hip is of particular importance for repeatedly adequate golf swings to prevent low back injuries in golfers.

We also observed that lumbar flexion motion (from the address to impact phase) and right-side lateral bending motion (after the impact phase) occurred to a greater extent in the golfers with LHIM than in the controls.

Increased flexion is associated with increased lumbar disc pressure and LBP, and most injuries of this type occur during the downswing.31,44 Therefore, increased lumbar flexion during the downswing (from the address to impact phase) in professional golfers with limited internal rotation of the left hip may contribute to LBP.

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Figure 3. Mean hip angular displacement during the golf swing between the normal hip internal motion (NHIM) and limited hip internal motion (LHIM) groups: (A) transverse plane, (B) coronal plane, and (C) sagittal plane. Abd, abduction; Add, adduction; ER, external rotator; Ext, extension; Flex, flexion; IR, internal rotator; Lt, left hip; Rt, right hip.

The error bars represent 6SD. **P \ .01.

Furthermore, increased lateral bending on the trailing side of the lumbar segment at the finish phase during the golf swing of golfers with LHIM may lead to spinal injuries. Sugaya et al50 found that 55% of Japanese tour

professional golfers had LBP, of whom over 50% had localized pain in the trailing side. They also found a correlation between right-side back pain and the follow-through phase of the golf swing. Radiographic analysis revealed significantly greater vertebral body and facet joint arthritis in the trailing side of golfers with LBP than in healthy golfers.

In this study, the correlation analysis showed a moderate correlation (r = 0.603) between the maximum pelvis left rotation angle during the golf swing and passive internal range of motion of the lead hip. This finding indicates that after impact, the left rotation angle of the pelvis decreased in line with hip joint constraints in the lead leg. Montgomery et al35 reported that stiffening of the lower body decreases the ability of the pelvis to rotate over the hip joints. Excessive or restrictive rotational movement in one area of the body segment increased loads on other body segments.35 Thus, limited hip internal rotation of the lead leg may lead to restricted left rotation of the pelvis and eventually excessive compensation motion of the lumbar spine.

Hip mobility can be affected by the presence of impairment or imbalance in the length and strength of muscles in the hip and pelvic area.22,53 Jull and Janda22 suggested that shortened or tight hip flexors and hamstrings usually are associated with weakness of the gluteal muscle. This was also confirmed in this study. The golfers with limited hip internal rotation of the lead leg had significantly shorter right-leg hamstrings and iliopsoas than the controls, and we observed that the golfers with limited hip internal rotation of the lead leg exhibited less strength in the right hip external rotator than the controls. The gluteus muscle (as rotators), biceps femoris (BF), and hip flexor (iliopsoas) in the trailing leg, which initiates pelvic rotation, show peak activity during the early downswing.3 Therefore, when the right hip external rotator muscles are weak, compensatory overuse of the BF and the hip flexor, as synergistic muscles, on the ipsilateral side occurs, eventually leading to muscle shortening of the BF and the hip flexor.42,49 Shortening of the hamstring in the trailing leg influences pelvic tilt2,23 and lumbar motion.16,49 Golfers with limited hip internal rotation of the lead leg showed a smaller anterior tilt of the pelvis during the downswing than the controls, possibly because of hamstring shortening. Normally, the hamstring in the lead leg is mainly activated as an accelerator during the early downswing,2 but hamstring muscle shortness or tightness may compensate for pelvic instability by constraining anterior pelvic tilt, thereby resulting in the reduction of neutral lumbar lordosis2 and associated anterior shear stress on the lumbar spine. Over time, repetitive practice with this abnormal lumbar spinal alignment is likely to impair lumbar spine movement and increase the risk of LBP.23 Also, iliopsoas shortness leads to greater lumbar flexion and an increased flexion moment on all segments of the lumbar spine on trunk flexion.49 Normally, the hip flexors in the trailing leg are primarily active until the impact phase, with lumbar flexion during the golf swing partly resulting from hip flexor activity. In this study, hip muscle shortness and

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strength imbalances in the group with limited hip rotation affected the length-tension relationship and associated arthrokinematic (rolling, spinning, or gliding) coordination of the lumbopelvic-hip region. These musculoskeletal characteristics could be possible causes of sports injuries during the golf swing because of alterations in movement patterns on the lumbopelvic-hip complex.

Notwithstanding the significant findings, our study has several shortcomings that should be addressed in future investigations. First, neuromotor control parameters (ie, muscle recruitment onset time, amplitude, and intersegment latency) are important elements of lumbopelvic-hip movement and coordination during the golf swing but were not measured in this study. For example, overactivation of the hip external rotators (ie, piriformis, gluteus maximus) in the lead leg, which can be measured with surface electromyography, has also been identified as an important limiting factor for hip internal rotation. In a future study, it would be of interest to examine muscle activation patterns in lumbopelvic-hip muscles in golfers with and without limited hip movement.8,9,30 Second, lumbar spinal stress in relation to limited hip motion merits further study because our kinematic data show a significant difference in lumbopelvic motion between the LHIM and NHIM groups. It is possible that a notable difference in maximum spinal rotation or flexion and side-bending moments at L5-S1 would be observed between golfers with and without a history of LBP during the golf swing.

Third, it is difficult to generalize our findings to female professional golfers. The study examined only male professional golfers because limitations in hip rotation are predominantly seen in male golfers.18 Lastly, this empirical study was unblinded, but future research should consider a blinded experiment to minimize the potential risk of bias.

Despite these limitations, our study demonstrates that limited hip joint movement, muscle strength, and length imbalances affect lumbopelvic movement in professional golfers. These findings have important clinical implications for the effective screening or examination of specific causes of pain (ie, muscle length and strength imbalances) as well as the prevention and management of golfers with LBP rather than addressing the location of the symptoms or sources of pain.

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