## 4 Discussion
In vivo measurements of healthy test persons with metal wires implanted in the pubic bone ramus (ramus ossis superior pubis) showed translation values of <2 mm and <3\({}^{\circ}\) rotation at the pubic symphysis when subjected to various strain-causing maneuvers [30]. Figure 5: Model of the development of pelvic torsion owing to muscular torque ratios between rectus femoris (RF) and hamstrings (HA). Arrow thickness represents traction force. (**a**) Different torque ratios right and left, but identical anterior–posterior torque ratio (2:1): pelvis neutral. (**b**) Increased anterior–posterior torque ratio (3:1): anterior pelvic tilt. (**c**) Different torque ratios left and right: unilateral pelvic tilt and pelvic torsion. SY = pubic symphysis. In a radiological study with asymptomatic test persons who were standing alternatingly on the left and right leg, [PERSON] et al. were able to prove that physiological movements up to 5 mm can occur at the public symphysis (functional instability) and that higher values are to be interpreted as a sign of \"macro\" instability [2]. Macro instabilities do not necessarily cause direct problems. They may, however, represent a significantly increased risk factor for the development of grain pain/injuries. [PERSON] and colleagues define a pelvis as stable if a vertical rotational symphyseal displacement of less than 11 mm occurs [31]. These data refer to traumatic pelvis injuries only, therefore, they cannot be generalized or even transferred to an athletic population. It is known that routine movements like walking already lead to slight physiologic movements that cause shearing forces in the public symphysis during the one-leg stance phase. This may explain why our test persons with higher pelvic torsion exhibited a significantly increased tenderness to palpation of the public symphysis. Even if they did not complain of pain in the public symphysis during everyday (sports) activities, we assume that strain in the area of the articular capsule caused by shearing forces may be a potential factor that might increase tenderness to palpation and sensitivity. Therefore, it may make sense to keep this in mind as a potential precursor for later pathologies and perform further studies on this topic. Some studies could show that the muscular balance between quadriceps and hamstrings depends on the type of sports performed. For example, [PERSON] et al. found significant differences in the hamstrings-quadriceps ratio between the dominant and non-dominant leg of adolescent soccer players [32]. [PERSON] et al. were able to show that these changes are adaptations to soccer-specific requirements [33]. This torsion of the hemi-pelvises may play an important role as a potentially pathogen mechanism in athletes, especially those with a heavy muscular imbalance between the dominant and non-dominant leg. This information is particularly relevant to our study because most of our participants were indeed soccer players. Key aspects pertaining to the prevention and rehabilitation of groin/public bone problems could be derived if the strength ratios of quadriceps and hamstrings were analyzed and improved, in the case of contralateral imbalances. [PERSON] et al. emphasize that imbalances of the leg muscles might be improved by including resistance exercises in the habitual training routines of youth soccer players [32]. To date, therapeutic focus has mostly been placed on strengthening adductors and rectus abdominis. In a prospectively randomized study, [PERSON] et al. were able to show that a group achieved significantly better results through active adductor training than through physical therapy treatment [34]. The results of our study point to a potential biomechanical-pathogen mechanism that should be taken into account in primary prevention and diagnostics of groin pain.