The Effect of Athletic Groin Pain on Whole-Body Vertical and Joint Stiffness: A Biomechanical Study to Injury Prevention and Rehab
GROIN PAIN
Athletic groin pain (AGP) is a common condition in field sports characterized by frequent accelerations, decelerations, and changes of direction. However, the biomechanical factors contributing to AGP are not well understood, and research in this area lags behind that of other sports injuries.
Stiffness has emerged as a modifiable risk factor in injury prevention research. Two types of stiffness are typically measured in dynamic athletic tasks: whole-body vertical stiffness and joint stiffness. Whole-body vertical stiffness reflects the resistance of the center of mass to vertical displacement under a given vertical ground reaction force, while joint stiffness refers to the resistance of a specific joint to rotation under a given moment of force.
Abnormal magnitudes of stiffness may increase the risk of injury by increasing peak force and/or rate of force development or by increasing the energy absorbed by soft tissues in a lengthened position.
In the case of AGP, stiffness may be particularly important as any alteration in the magnitude or manner of loading may overload the musculo-tendinous and bony structures surrounding the pubic symphysis region. However, to date, no research has examined whether AGP affects stiffness.
The aim of this study was to determine if AGP affects whole-body vertical and joint stiffness and whether rehabilitation is associated with a change in stiffness. Sixty-five male subjects with AGP who had completed a three-stage rehabilitation program focusing on intersegmental control and strength, linear running mechanics, and change of direction mechanics were examined, along with fifty male matched uninjured controls. The Copenhagen Hip And Groin Outcome Score (HAGOS) was examined pre-and post-rehabilitation.
Assessment included a biomechanical examination of stiffness during a lateral hurdle hop test. The AGP participants were tested pre- and post-rehabilitation, while controls were tested once. Reflective markers were placed at bony landmarks on the lower limbs, pelvis, and trunk, and lower extremity kinematics and kinetics were captured using 8 infrared cameras and two 40 × 60 cm force platforms.
The results showed that vertical whole body, ankle plantar flexor, knee extensor, and hip abductor stiffness were significantly lower in the AGP group pre-rehabilitation compared to the uninjured control group. However, post-rehabilitation, hip abductor stiffness increased significantly and ankle internal rotator stiffness decreased significantly in the AGP group. After rehabilitation, vertical whole body, ankle plantar flexor, and knee extensor stiffness remained significantly lower in the AGP group compared to the uninjured control group, while hip abductor stiffness was no longer significantly different between the two groups.
Furthermore, all AGP subjects completed rehabilitation in a median of 9.14 weeks and reported significant improvements in five HAGOS subscales, with only one subsection not changing significantly.
In conclusion, this study provides novel evidence that AGP affects whole-body vertical and joint stiffness and that rehabilitation is associated with changes in hip abductor and ankle internal rotator stiffness. These findings may have implications for injury prevention and rehabilitation strategies for AGP in field sports as such suggesting that hip abduction stiffness may represent a target for rehabilitation.
Source : Gore SJ et al. (2018) Is stiffness related to athletic groin pain? Scand J Med Sci Sports 28:1681–1690.
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