Effects of sensorimotor training on pelvic stability and balance in runners

Introduction: Running has increased significantly in recent years due to its benefits and practicality. However, like any sport, running poses a risk of injury, leading to the need for clinical intervention and even its practitioners quitting the sport. Therefore, preventive strategies seeking to minimize the occurrence and consequences of such risk factors in these athletes are pivotal. Objective: To investigate the preventive effects of a sensorimotor training protocol on the balance and pelvic stability of runners. Methods: The study sample consisted of fourteen 10-km runners of both genders divided into two groups: the control group (CG) and the sensorimotor training group (SMTG). Both groups were evaluated using the single-leg stance test (static balance), Trendelenburg test (pelvic stability), and hop test (dynamic balance). The SMTG underwent 16 interventions, while the CG did not receive any intervention. Results: The SMTG showed a significant increase in the permanence time of the single-leg stance test (p < 0.05) and a reduction in knee valgus during impulse and landing moments of the single hop test only in the right lower limb (p < 0.05), while the CG showed no significant difference in all tests applied (p > 0.05). Regarding pelvic stability, there was no significant difference in any of the groups. Conclusion: The proposed protocol significantly improved the static balance of the SMTG, but not the pelvic stability.


Introduction
The search for a healthy lifestyle and a better quality of life are goals present in the reality of numerous individuals.For these reasons, there is an increasing demand for regular physical exercise, especially aerobic exercise, among which street running stands out due to its practicality, low cost, and the multiple body benefits generated, such as lower risk of cardiovascular disease. 1 As in any other sport modality, however, street running exposes practitioners to the risk of injuries, and anywhere from 19.4 to 92.4% of musculoskeletal changes occur in the lower limbs of runners, 2,3 especially in the ankle/foot, knee, and hip joints.[2][3][4] These changes may contribute to injuries at these sites, especially if there are sensorimotor deficits, including more significant postural sway and/or joint misalignment.5 Moreover, such injuries can be severe enough to reduce or even keep athletes from practicing sports, in addition to leading to the need for medical care. 1 Hence, the use of preventive interventions to reduce the incidence and impact of these injuries among runners is pivotal.In this scenario, physiotherapy uses a vital resource used in the sports environment: sensorimotor training, which aims to improve proprioception and muscle response, improving dynamic joint stability and, consequently, reducing the risk of injuries.6 As a result, given the risk of injuries in sports and the need for preventive measures that seek not only to reduce the impact of these injuries but also improve the performance of street runners, this study aimed to investigate the effects of a sensorimotor training protocol on the dynamic and static balance and pelvic stability of street runners.

Sample
The sample was composed of fourteen 10-km street runners (eight men and six women) who signed the informed consent form.As established by the National Health Council on ethical guidelines for research with human subjects, this study was approved by the Research Ethics Committee of the Pontifical Catholic University of Minas Gerais (CAAE: 7697.1617.9.0000.5137).
After selecting participants who met the inclusion criteria, the first eight participants were randomly assigned to two groups.Then, to have a homogeneous distribution between the groups, the remaining participants were paired by sex, age, body mass, and height.The participants were thus divided into two groups, each composed of four men and three women: the control group (CG), with a mean age of 47.1 years (± 15.8), mean height of 166 cm (± 9.7), and mean body mass of 64.1 kg (± 9.9), and the sensorimotor training group (SMTG), with a mean age of 41.9 years (± 12.5), mean height of 171.3 cm (± 9.3), and mean body mass of 74.9 kg (± 10).
To meet the inclusion criteria, the participants needed to be over 18 years old, regularly practice street running,

Static balance
The static balance was evaluated using the singleleg stance test, in which the athlete remained on one leg with their eyes closed and their upper limbs crossed over the trunk for 30 seconds.The task was interrupted when the participant did not maintain a stable posture, and the maximum time achieved was recorded.7 Two trials were performed for each lower limb, and the mean time spent in both trials was considered the dependent variable.

Pelvic stability
The pelvic stability was evaluated using the Trendelenburg test and performed similarly to the single-leg stance test, although the participants kept their eyes open.After 30 seconds, the participant was photographed and the pelvic alignment was observed.8 The positive sign was considered according to the contralateral pelvic drop for the supporting lower limb, where an elevation of the ipsilateral pelvis of this limb occurs, 8,9 and therefore, the use of the angulation measurement between the iliac spines was determined.
The dependent variable was the joint angle of the lower limb (anterosuperior iliac spine, midpoint of the patella, and center of the malleoli), where closer to 180º indicated greater joint alignment.

Dynamic equilibrium
In the single-leg hop test, 9 we attempted to analyze the knee valgus angle (anterosuperior iliac spine, midpoint of the patella, and midpoint between the malleoli), which was considered the dependent variable since knee valgus is considered the medial displacement of the knee beyond the thigh-foot alignment.10 The analysis was performed by video in two moments: impulsion (the instant of completing the single-leg squat; moment 1) and landing (the instant when the entire sole of the foot touched the ground; moment 2), where closer to 180º indicated greater joint alignment.

Sensorimotor training protocol
After the initial evaluation, the CG did not receive any intervention for eight weeks, while the SMTG had For the landing exercise, the athletes were instructed to perform the exercises as quickly and stably as possible (3 x 10 repetitions).
The sensorimotor training protocol progressively became more difficult every four interventions (Table 1).After the sixteen interventions, both groups were submitted to a final evaluation (identical to the initial one) to investigate and compare the effects of the training.

Results
Most of the participants in this sample (35.7%) had an average street running experience of 1 to 3 years and reported injuries related to the sport and withdrawal from the sport (Table 2).
significant difference between evaluations (p = 0.001) and interaction evaluation and group (p = 0.001), albeit there was no difference between groups (p = 0.186).
The significant interaction indicates distinct behaviors in the groups.In this case, the time spent on the single-leg stance with eyes closed increased in the SMTG in both lower limbs; in the CG, it only increased in the right lower limb.The behavior of both groups in this test before and after the intervention is illustrated in Figure 2A.
The mean and standard deviation for the length of stay in the right and left single-leg stance for both groups and assessments and p values in the intergroup and intragroup analyses determined by the Bonferroni post hoc test are listed in Table 3.
The  0.798), although there was a significant increase in the length of stay in the right single-leg stance (p = 0.026), which is likely due to the learning effect in the test or by the right lower limb dominance.

Pelvic stability -Trendelenburg test
The joint angle represents the pelvic alignment, and the statistical analysis did not indicate any significant difference for the group (p = 0.474) and evaluation (p = 0.110), albeit there was a notable difference for the interaction between group and evaluation (p = 0.005).The interaction occurred due to the different behavior between the groups, whereby the joint angle decreased between the evaluations in the CG, while the joint angle increased in the SMTG, which indicates better pelvic alignment in this group after the proposed intervention (Figure 2B).Additionally, Table 3 shows the and, consequently, their quality of life.17 Thus, in order to avoid the removal of athletes from sports, future medical expenses, and the consequent impact on quality of life resulting from injuries, it is pivotal to identify the deficits that these athletes present to develop preventive interventions for this population.There is no doubt about the high prevalence of lower limb injuries in runners because the impact force at this location during training can reach three times the body mass.Given the above, this study proposed an evaluation using easily applicable tests that allowed the neuromuscular control to be evaluated even in static situations and experimental laboratory conditions while employing software available to health professionals.

Conclusion
The proposed sensorimotor training protocol led to overall improvements, especially in static balance, in the athletes of the sensorimotor training group.Nevertheless, the control group did not present alterations in static and dynamic balance or pelvic stability.
sixteen 30-min physiotherapeutic interventions twice a week.Each intervention consisted of joint warm-ups and muscle stretching for 10 min and sensorimotor training for 20 min.The warm-up occurred through active muscle stretching exercises and joint movements of the trunk, hips, knees, and ankles.The sensorimotor training was divided into two 10-min sessions.Session 1 emphasized balance, proprioception, and lumbopelvic stability training through exercises that stimulated balance reactions on unstable surfaces with different perturbations (Figure1).On the proprioceptive disk, the athletes were instructed to remain as stable as possible (3 x 30 s), and on the balance board and with the same instructions, the athletes threw a 2 kg ball to the therapist (3 x 10 repetitions).Session 2 emphasized training agility, coordination, and landing on the ground through different speed exercises, changes in direction, sudden stops, and landing on unstable surfaces (Figure1).For the agility and coordination training, the participants were instructed to perform the exercises as quickly as possible while maintaining their lower limbs aligned (3 x 30 s).

Figure 1 -
Figure 1 -Demonstration of the sensorimotor training.
post hoc tests indicated that the CG and SMTG showed no significant difference for the length of stay in the right (p = 0.728) and left (p = 0.700) single-leg stance of the initial evaluation.Nonetheless, the post hoc tests indicated a significant difference between the CG and SMTG for the length of stay in the right (p = 0.05) and left (p = 0.019) single-leg stance of the final evaluation.Additionally, the post hoc analysis showed that the SMTG significantly increased in the static balance length of stay time in the right (p = 0.001) and left (p = 0.012) singleleg stance after eight weeks of the sensorimotor training protocol, which shows that this protocol had a positive effect on the static balance of street runners.For the CG, the post hoc tests did not show a significant difference for the length of stay in the left single-leg stance (p = Static balance -Single-leg stance test For the time spent on the single-leg stance with eyes closed (in seconds), the statistical analysis indicated a

7 Figure 2
Figure 2 -A: Mean and standard deviation of the time spent on the single-leg stance (in seconds) for the sensorimotor training group (SMTG) and control group (CG) in the initial and final evaluations of the right (RLL) and left lower limbs (LLL).*Indicates significant difference.B: Mean and standard deviation of the measurements of joint angles (pelvic alignment) when performing the Trendelenburg test for the SMTG and CG at the initial and final evaluation of the RLL and LLL.C: Mean and standard deviation of the measurements of joint angles (knee valgus) when performing the hop test at the first (impulsion) and second moments (landing) for the SMTG and CG in the initial and final evaluations of the RLL and LLL.
The balance system aims to allow the minimum displacement of the body's center of gravity, thus improving postural control.18Postural control, in turn, allows an adequate posture to perform the specific movements required by the sport.19 Individuals with greater postural sway, and therefore poorer balance, were seven times more likely to suffer an ankle sprain compared to individuals without this sway.4 This is because the compliance of several factors, especially proprioception, is essential for balance to be adequate.Proprioception means awareness of position, movement, and resistance of objects related to the body, 20 and it is essential for joint stabilization.21 Proprioceptive information comes from muscle (muscle spindle) and tendon (Golgi tendon organ) receptors of different musculoskeletal structures.5 This information generated by the mechanoreceptors is processed in the central nervous system and generates forms of muscle activation for joint stabilization, which optimizes dynamic joint stabilization and postural control.5 When this mechanism is altered (i.e., injuries), processing does not occur adequately and, therefore, joint stabilization may not occur effectively, intensifying the risk of injuries during sports activities.5 Given this scenario, when assessing static and dynamic balance, especially during single-leg hopping, which is a constant movement during running exercises, it is possible to identify deficits in postural control and dynamic joint stabilization, respectively.In addition, while running, the lower limb joints are constantly used and, for these movements to occur adequately, the lumbopelvic complex has the role of providing stability.21 This fact occurs because this region acts as a place of transmission of the forces generated in the lower limb to the trunk during running, therefore requiring good stability to reduce injuries.11 Postural changes in these locations, including pelvic anteversion and lumbar hyperlordosis, can overload the posterior facet joints of the lumbar spine and, when added to the overload from the repetitive impact of running, cause arthrosis in this region.22,23 Therefore, evaluating the stability of the lumbopelvic complex and interventions that seek to optimize the function of this region are indispensable.a significant difference between the CG and SMTG for the joint angle of the RLL at the moment of landing (p = 0.012), albeit there was no significant difference in RLL at the moment of impulsion (p = 0.093) or for the LLL at the moment of impulsion (p = 0.119) and landing (p = 0.168).Furthermore, the post hoc tests indicated a significant difference for the SMTG between the initial and final evaluations for the RLL and LLL joint angle at the moment of impulsion (p = 0.036 and p = 0.047, respectively) and landing (p = 0.05 for both).For the CG, however, the post hoc tests did not show any significant difference between the initial and final evaluations for the joint angle of the RLL and LLL at the moments of impulsion (p = 0.167 and p = 0.314, respectively) and landing (p = 0.122 and p = 0.139, respectively).Discussion This study proposed to investigate the effects of sensorimotor training on 10-km street runners.After the 16 interventions of the proposed training protocol, the athletes showed improved static balance in only one of the lower limbs in dynamic balance and no improvement in lumbopelvic stability.These facts can be observed, respectively, in the increased length of stay in the singleleg stance and increased joint angles, which approached 180º in the right lower limb, indicating better joint alignment at the moment of impulsion and landing, and, finally, in the lack of angular change of the pelvis in the single-leg stance.In addition to the significant difference that only occurred in the static balance, the effect size in this item in the right and left lower limbs was large and above average, respectively.In the dynamic balance at the moment of landing, such an effect was also considered significant, indicating the relevance of the gains found herein.
Moreover, the proposal of sensorimotor training using resources that are generally easily accessible to professionals was met.Nonetheless, the main limitation was the number of participants, as there were only seven athletes in each experimental group.For this reason, despite the knowledge of the effects of sensorimotor training on the dynamic and static balance of street runners, further research must be carried out and with a larger number of athletes and a more extended period of intervention with sensorimotor training to verify the effects on static balance and lumbopelvic stability.

Table 1 -
Evolution of the sensorimotor training protocol

Table 3 -
Mean and standard deviation of the athletes (n = 7) from the sensorimotor training group (SMTG) and the athletes (n = 7) from the control group (CG) in the initial evaluation (IE) and final evaluation (FE) for the lower limbs (right, RLL; left, LLL) and in the first (M1; impulsion) and the second moment (M2; landing) for the one-leg stance, Trendelenburg and hop tests