Inconsistent anticipatory postural adjustments (APAs) in rugby players: a source of injuries?

Abstract

BackgroundWe are developing since 2010 with Thales and the Fédération Française de Rugby (FFR) M-Rex, a new kind of rugby scrum simulator. The study questioned whether it could improve safety and protect players from injury by using it as a tool for training/coaching the packs.AimTo explore the anticipatory postural adjustments (APAs) during the engagement of the ruck, because these predictive neck and back muscles contractions protect the spinal cord at the time of impacts, which is crucial to prevent injuries.MethodsWe quantified the kinematics and the EMG activities in high-level front row players during their initial engagement, when scrummaging with M-Rex. All studies were performed with one player interacting with the robot, at first, and then with the three players acting together.ResultsFor most of the tested high-level players, the APA latencies were highly variable from trial to trial even though the engagement resulted in similar impacts. At time, the onset of the electromyography activity in the neck and back muscles showed latencies inferior to 50 ms or even close to zero prior to the impact, which rendered muscle contractions inefficient as APAs. We were also unable to identify clear muscular synergies underlying the APAs because of their great variability on a trial-to-trial basis. Finally, the APAs were not related to the amplitude of the ensuing impact and were asymmetric in most trials. All these characteristics held true, whether the player was playing alone or with two other frontline players.ConclusionOur result suggest that APAs should be systematically tested in high-level rugby players as well as in any high-level sport men at risk of neck and back injuries. Because APAs can be efficiently trained, our study paves the way to design individual position-specific injury prevention programme.

Collaborative sensorimotor intelligence: the scrum as a model

“…It could be related to the fact that the synchronisation of the players was difficult over a very short and high impact. Finally, in a previous study (Wang et al 2018),10 we showed that the anticipatory postural adjustments during the transient phase were highly variable, which was an additional source of potential injuries.…”

“…Initially developed to analyse the risk of scrum accidents and to improve players safety, it turned out to be a valuable tool for training/coaching the packs of the national teams and to study collective sensorimotor intelligence. In a first study,10 we have shown that anticipatory postural adjustments (APAs) should be tested in highlevel rugby players and probably also in any high-level sport men at risk of neck and back injuries. Being the fact that recent studies had shown that APAs can be efficiently trained, our study also paved the way to design individual position-specific injury prevention programme taking into account the player’s APAs characteristics and his/her previous injuries.…”

Fascia Is Able to Actively Contract and May Thereby Influence Musculoskeletal Dynamics: A Histochemical and Mechanographic Investigation

“…MFB driven stiffness changes in lumbar fasciae may possibly also influence the complex dynamics of anticipatory adjustments which play an important role in human postural regulation (Park et al, 2014; Wang et al, 2018). In addition, minor fascial stiffness changes, as observed in our study, could be involved in – at least some cases of – the phenomenon of vertebral somatic dysfunction described as a minor intervertebral disorder in the osteopathic literature (Fryer et al, 2004; Ho, 2015; Tozzi, 2015).…”

Two Aspects of Feedforward Control During a Fencing Lunge: Early and Anticipatory Postural Adjustments

“…However, when the postural disturbance is associated with the displacement of the whole body, APA may play a role in generating forces that facilitate the execution of the movement ( Bouisset and Do, 2008 ). Furthermore, APA may be also associated with stabilization of the given joint and reduce the number of redundant degrees of freedom ( Bouisset and Zattara, 1987 ; Wang et al, 2018 ). Muscle activation during APA commonly induces the displacement of the center of pressure (COP) in the opposite direction to the direction of forthcoming disturbance ( Belenkiy et al, 1967 ; Cordo and Nashner, 1982 ).…”