Impact des troubles musculosquelettiques sur les mécanismes du contrôle postural chez
les adolescents-hockeyeurs de niveau élite et intervention en Reconstruction Posturale®

Adolescent hockey players can suffer from musculoskeletal disorders (MSD) resulting from excess muscle tension that can lead to dysmorphisms, muscle imbalances as well as inadequate standing posture. The consequences of these changes often lead to unnecessary overload of the musculoskeletal system (MSS), disturbances in postural control mechanisms and eventually the development of muscular and joint pain. Very few interventions are design to address MSD by rebalancing muscle tension. One of the clinically tested interventions is Postural Reconstruction® (PR). Our first objective was to identify the characteristics of postural control among a population of elite adolescent-hockey players when the somatosensory system is disturbed while standing in a quasi static position barefoot and on skates. Secondly, we assessed the impact of an intervention in PR on various clinical and biomechanical variables among a population of elite adolescent hockey players suffering from MSD. Sixty seven elite adolescent hockey players, 15 to 18 years of age participated in the study. The postural control of fifty seven players was assessed in standing using two force platforms, in eyes open (EO) and eyes closed (EC) conditions barefoot on hard surface and on foam. From that group, thirty five players were also assessed on skates, EO and EC. Then, nine players suffering from MSD were selected to participate in the intervention protocol in RP consisting in the application of six therapeutic sessions held once a week for six consecutive weeks. Center of pressure (COP) movements under the feet was calculated in the antero-posterior (AP) and medio-lateral (ML) directions. To account for the performance of the postural control system, mean COP velocity and displacements as well COP range were used. The variables retained to account for the strategies used to maintain balance in the upright position were weight baring asymmetry, concordance of the COP trajectory as well as COPc for the contribution of the ankle strategy and COPv for the contribution of the hip strategy. Finally, the impact of PR intervention was assessed on pain level, functional capacity and postural biomechanical variables. Our results show that among elite adolescent hockey players, the performance of the postural control in standing in a quasi static position is more disturbed by changes somatosensory information in ML direction while in AP, the absence of visual information as well as changes in somatosensory information significantly affect the performance. In all experimental conditions, and in both directions, we observed a remarkably high mean velocity, ranging between 18 to 22 mm/sec. As for the strategies, independent of the experimental condition, we observed total dominance of the ankle strategy in AP while in ML, the hip strategy dominated with a 25 % contribution for the ankle strategy. On skates, in ML direction, no significant changes were observed in the performance. However, in AP, we observed a significant increase in the mean COP velocity, EO and EC, and significant increase in COP range, EO only. As for the strategies, we observed the same dominance but the contribution on the ankle strategy in ML was more modest, that is less than 12 %. For players suffering from MSD, our results show that six sessions of PR significantly improved the level of pain, functional capacity and body alignment in standing. Pre intervention in ML, we observed a significantly higher contribution of the ankle strategy to the control of the COPnet and post-intervention, a return to normal values. The impact of the PR intervention on postural control performance was not significant in ML and AP. In conclusion, our results show that in the early stage, a PR intervention has a greater impact on postural control stratégies rather than performance.

Keyphrases: Muscle tone, Musculoskelettal disorders, Postural control, Standing posture, Postural Reconstruction®, Rehabilitation