The Characteristic of Dynamic Balance Ability and Hip Flexibility in Soccer Players with a History of the Groin Pain: A Preliminary Study

The purpose of this study was to investigate the characteristic of hip flexibility and dynamic balance ability in the soccer players with the groin pain. The study consisted 17 male college soccer players. All participants were divided into the Groin Pain (GP) group and non-GP group, according to a history of the groin pain. Hip passive Range of Motion (ROM) test and the modified Star Excursion Balance Test (mSEBT) was conducted in all participants. The Mann–Whitney U test or Student’s t-test was selected to identify differences in hip ROMs and results of the mSEBT in kicking keg and supporting leg between groups. Hip abduction angle of kicking leg in the GP group were smaller than that in the non-GP group in the kicking leg (p < 0.05). There were no differences in other hip ROMs between groups (p > 0.05). There was no difference in results of the mSEBT between groups in both legs (p > 0.05). Our results were newly revealed that soccer players with the groin pain had poor hip abduction range of motion in comparison with those without the groin pain. This finding suggested that a poor hip abductor range of motion may affect the kicking biomechanics in soccer players with the groin pain.

Groin pain syndrome is a widely known as the common injures in soccer and football. The groin pain means “pain in the groin area” and the different symptoms referred by the athlete identify different kinds of groin pain, with as many different causes [1]. In recent reports, the groin pain in athletes is considered to include the clinical entities for groin pain (Adductor-related, iliopsoas-related, inguinal-related and pubic-related groin pain), hip-related groin pain, and other causes of groin pain in athletes [2].

Previous systematic review reported that the factors differentiating athletes with groin pain from those without these injuries [3]. Particularly, poor flexibility of hip was mentioned as one of physical functions related to the groin pain [3]. This suggested that sufficient hip mobility may lead to reduction or prevention of the groin pain [4]. In addition, hip joint flexibility has also been associated with dynamic balance performance [5,6] and that with the leg reach for the medial direction was significantly positively correlated with hip internal rotator tightness and hamstring tightness [7]. These studies suggested that athletes with the groin pain may have lower dynamic balance ability, as well as having poor hip flexibility.

Soccer players frequently perform the kicking motion in the game and practice and that is an important technique in soccer [8]. The supporting leg particularly plays a role to attenuate the landing impact in the initial foot contact during kicking [9]. Furthermore, the dynamic stability of the supporting leg contributes to the swing velocity of kicking leg and kicking accuracy [9,10]. These suggested the poor hip flexibility and dynamic balance ability in soccer players may alter their kicking biomechanics and soccer performance. However, no previous study has focused on whether soccer players with a history of the groin pain have poor hip flexibility and the dynamic balance ability. Therefore, we investigated the characteristic of hip flexibility and dynamic balance ability in the soccer players with the groin pain. The findings of this study can be preliminary data to verify whether these physical functions in soccer players with the groin pain may affect kicking biomechanics.

The study consisted of 17 male college soccer players (age, 20.8 ± 0.3 years; height, 173.0 ± 5.1 cm; weight, 65.8 ± 3.9 kg; soccer experience, 10.5 ± 2.1 years). This study conducted in the motion analysis laboratory of the International University of Health and Welfare, Narita Campus, Chiba, Japan. All participants were right-footed in the dominant leg (kicking leg) and left-footed in the nondominant leg (supporting leg). The inclusion criteria were: age, >18 years; playing soccer experience, >8 years; and absence of current pain in the lower extremities during their daily activities, according to a previous study [11]. The exclusion criteria included some orthopedic histories of the trunk, hip, or knee, and any ankle surgeries or serious injuries. All participants gave written informed consent for participation prior to testing. The study was carried out in accordance with the Declaration of Helsinki and was previously approved by ethic committee of the International University of Health and Welfare (19-Io-62).

Prior to inclusion in this study, all participants were required to answer a questionnaire including about physical characteristics, current medical information, and medical history, including the groin pain. For the medical history of the groin pain, participants who had had groin pain were required to mark the groin area shown in the questionnaire. They were divided into the Groin Pain (GP) group, while them who had no history of the groin pain was the non-GP group.

Hip Range of Motion (ROM°) in bilateral flexion, extension, abduction, internal, and external rotation were passively measured using a standard goniometer, which has been shown to be a valid and reliable instrument for measuring hip ROM [12]. All measurements were performed according to the methods of the Japanese Association of Rehabilitation Medicine and the Japanese Orthopedic Association [13].

All participants conducted the modified Star Excursion Balance Test (mSEBT) which is a reliable test for measuring single limb stance excursion distances [14,15]. The mSEBT was conducted according to the method by Tamura, et al. [11]. The participants, standing on their dominant (kicking leg) or nondominant leg (supporting) in the center of the grid lines, performed maximum reach of each leg in three directions (anterior, posteromedial, and posterolateral directions) before returning to the start position. The distances (cm) for three reach directions of the mSEBT of each leg were normalized by participant’s leg length (LL, cm) from the anterior superior iliac spine to the medial malleolus, respectively. The means and standard deviations (%LL) of each direction of the mSEBT results were calculated as the average from three successful trials in each direction. The mSEBT composite score (%LL) were calculated by summing the results of three reach directions and normalizing the results to leg length [16].

The Kolmogorov–Smirnov test was used to confirm that hip ROMs and results of the mSEBT were normally distributed (p < 0.05). Depending on whether a normal distribution existed, the Mann–Whitney U test or Student’s t-test was selected to identify differences in hip ROMs and results of the mSEBT in each leg between the GP group and non-GP groups. In order to mitigate the effects of the low numbers of participants in each group, Cohen’s d effect sizes were calculated for all analyses, to illustrate the magnitude of the differences between the groups. A p < 0.05 was considered statistically significant. All statistical analyses were conducted using IBM SPSS Statistics for Mac, version 24.0 (IBM Corporation, Armonk, NY, USA).

Based on a history of the groin pain, there were 8 players in the GP group and 9 players in non-GP group. There were no significant differences in physical characters (age, height, weight, and soccer experience) between groups (p > 0.05).

For the results of mSEBT, there was no difference in anterior, posteromedial, posterolateral directions, and the composite score between groups in both legs (p > 0.05, table 1).

For the results of hip ROMs, hip abduction angle of kicking leg in the GP group were smaller than that in the non-GP group in the kicking leg (p < 0.05, table 1). There were no differences in other hip ROMs between groups in both legs (p > 0.05, table 1).

Our study revealed that the hip abduction ROM of kicking leg in the GP group was less than that in the non-GP group. This result suggested that the flexibility of hip abduction was associated with a history of the groin pain. Previous studies have reported that individuals with the groin pain had restricted hip internal rotation. In this study, it was newly revealed that soccer players with the groin pain had poor hip abduction range of motion in comparison with those without the groin pain, while hip internal rotation did not differ. This result is considered to be caused by the adductor-related problem which is one of the factors of the groin pain syndrome. Recently, the definition of the groin pain syndrome has been recognized as including adductor-related groin pain; for example, adductor tendinopathy, adductor enthesopathy, or femoro-acetabular impingement [2]. These adductor-related disorders may promote poor hip abduction range of motion. Therefore, the results of this study suggest the need to focus on poor hip abduction range of motion in soccer players with the groin pain.

The mSEBT is a clinically applicable test for providing accurate assessment of the dynamic balance ability of the lower extremities [15]. In this study, the results of the mSEBT showed that the dynamic balance ability in the GP group did not differ from that in the non-GP group. This result was showed for both the kicking leg (dominant leg) and the supporting leg (non-dominant leg). Our results clarified that the dynamic balance ability in soccer players did not relate to a history of the groin pain. Therefore, these results suggest that poor dynamic balance ability may not affect kicking biomechanics or soccer performance.

Our results indicated that a poor hip abductor range of motion may affect the kicking biomechanics in soccer players with the groin pain while the effects of the dynamic balance were not revealed. It has been yet clarified whether poor hip abduction range of motion in soccer players may affect kicking biomechanics. The findings of this study provide evidence to investigate those soccer players with the groin pain may alter kicking biomechanics due to the effects of poor hip abduction range of motion.

This work was supported by JSPS KAKENHI Grant Number JP20K19512. The authors would like to thank all participants and all assistants in this study.

1. Tsukada S, Niga S, Nihei T, Imamura S, Saito M, Hatanaka J. Iliopsoas disorder in athletes with groin pain: prevalence in 638 consecutive patients assessed with MRI and clinical results in 134 patients with signal intensity changes in the iliopsoas. JB JS Open Access. 2018 Mar 12;3(1):e0049. doi: 10.2106/JBJS.OA.17.00049. PMID: 30229237; PMCID: PMC6132908.
2. Weir A, Brukner P, Delahunt E, Ekstrand J, Griffin D, Khan KM, Lovell G, Meyers WC, Muschaweck U, Orchard J, Paajanen H, Philippon M, Reboul G, Robinson P, Schache AG, Schilders E, Serner A, Silvers H, Thorborg K, Tyler T, Verrall G, de Vos RJ, Vuckovic Z, Hölmich P. Doha agreement meeting on terminology and definitions in groin pain in athletes. Br J Sports Med. 2015 Jun;49(12):768-774. doi: 10.1136/bjsports-2015-094869. PMID: 26031643; PMCID: PMC4484366.
3. Mosler AB, Agricola R, Weir A, Hölmich P, Crossley KM. Which factors differentiate athletes with hip/groin pain from those without? A systematic review with meta-analysis. Br J Sports Med. 2015 Jun;49(12):810. doi: 10.1136/bjsports-2015-094602. PMID: 26031646; PMCID: PMC4484362.
4. Tak I, Engelaar L, Gouttebarge V, Barendrecht M, Van den Heuvel S, Kerkhoffs G, Langhout R, Stubbe J, Weir A. Is lower hip range of motion a risk factor for groin pain in athletes? A systematic review with clinical applications. Br J Sports Med. 2017 Nov;51(22):1611-1621. doi: 10.1136/bjsports-2016-096619. Epub 2017 Apr 21. PMID: 28432076; PMCID: PMC5754850.
5. Freke M, Kemp J, Semciw A, Sims K, Russell T, Singh P, Crossley K. Hip strength and range of movement are associated with dynamic postural control performance in individuals scheduled for arthroscopic hip surgery. J Orthop Sports Phys Ther. 2018 Apr;48(4):280-288. doi: 10.2519/jospt.2018.7946. PMID: 29607762.
6. Robinson R, Gribble P. Kinematic predictors of performance on the star excursion balance test. J Sport Rehabil. 2008 Nov;17(4):347-357. doi: 10.1123/jsr.17.4.347. PMID: 19160909.
7. Endo Y, Sakamoto M. Relationship between lower extremity tightness and star excursion balance test performance in junior high school baseball players. J Phys Ther Sci. 2014 May;26(5):661-663. doi: 10.1589/jpts.26.661. Epub 2014 May 29. PMID: 24926127; PMCID: PMC4047227.
8. Lees A, Nolan L. The biomechanics of soccer: a review. J Sports Sci. 1998 Apr;16(3):211-234. doi: 10.1080/026404198366740. PMID: 9596356.
9. Inoue K, Nunome H, Sterzing T, Shinkai H, Ikegami Y. Dynamics of the support leg in soccer instep kicking. J Sports Sci. 2014;32(11):1023-1032. doi: 10.1080/02640414.2014.886126. Epub 2014 Feb 28. PMID: 24575753.
10. Chew-Bullock TS, Anderson DI, Hamel KA, Gorelick ML, Wallace SA, Sidaway B. Kicking performance in relation to balance ability over the support leg. Hum Mov Sci. 2012 Dec;31(6):1615-1623. doi: 10.1016/j.humov.2012.07.001. Epub 2012 Aug 30. PMID: 22939850.
11. Tamura A, Shimura K, Inoue Y. Hip flexibility and dynamic balance ability in soccer players with functional ankle instability. Trauma Care. 2021;1:206-214. https://tinyurl.com/5aee8va4
12. Brosseau L, Tousignant M, Budd J, Chartier N, Duciaume L, Plamondon S, O'Sullivan JP, O'Donoghue S, Balmer S. Intratester and intertester reliability and criterion validity of the parallelogram and universal goniometers for active knee flexion in healthy subjects. Physiother Res Int. 1997;2(3):150-166. doi: 10.1002/pri.97. PMID: 9421820.
13. Yonemoto K, Ishigami S, Kondo T. The method guidelines for range of motion measurement. Japanese J Rehabil Med. 1995;32(4):207–217.
14. Onofrei RR, Amaricai E, Petroman R, Suciu O. Relative and absolute within-session reliability of the modified Star Excursion Balance Test in healthy elite athletes. PeerJ. 2019 Jun 12;7:e6999. doi: 10.7717/peerj.6999. PMID: 31223524; PMCID: PMC6571006.
15. Kinzey SJ, Armstrong CW. The reliability of the star-excursion test in assessing dynamic balance. J Orthop Sports Phys Ther. 1998 May;27(5):356-360. doi: 10.2519/jospt.1998.27.5.356. PMID: 9580895.
16. Van Lieshout R, Reijneveld EA, van den Berg SM, Haerkens GM, Koenders NH, de Leeuw AJ, van Oorsouw RG, Paap D, Scheffer E, Weterings S, Stukstette MJ. Reproducibility of the modified star excursion balance test composite and specific reach direction scores. Int J Sports Phys Ther. 2016 Jun;11(3):356-365. PMID: 27274422; PMCID: PMC4886804.