Reactive Neuromuscular Training - RNT
Introduction[edit | edit source]
It was Voight who proposed the concept of Reactive Neuromuscular Training (RNT) in 1990.The aim was to design a rehabilitation program to restore dynamic stability and fine motor control at an injured joint, minimize the need for verbal and visual instruction from the physical therapist or athletic trainer, and respond to stimulus created by outside force eg: elastic band. That challenge the dynamic stability and proprioception, which can be defined as awareness of posture, movement, and changes in equilibrium and the knowledge of position, weight, and resistance of objects in relation to the body, respectively. This type of training focuses on appropriate body positioning and posture to promote proper dynamic muscular stabilization during functional activities, thus allowing for the control of abnormal joint translation during functional activities. These activities are designed to emphasize quality of movement before quantity of movement.
Proprioception[edit | edit source]
Proprioception is a specialized variation of the sensory modality of touch that encompasses the sensation of joint movement (kinesthesia) and joint position (joint position sense). the term proprioception was introduced by Sherrington in 1906 and comes from the Latin words (re)ception (the act of receiving) and proprius (one’s own). Information about the position and movement of the joint is available from the peripheral receptors located in and around its articular structures . These specialized receptors provide information to the CNS regarding joint position sense and movement. The mechanoreceptors do this by converting mechanical deformation into electrical impulses that are sent into the CNS. This proprioceptive information, in turn, via descending efferent pathways, influences joint stiffness, coordinated motor patterns, and reflex activity to provide enhanced joint stability. The information gathered is processed at three levels. At the spinal level, responses provide dynamic muscular stabilization through activation of the spinal reflexes. The cerebellum regulate posture and balance by integrating input from vestibular, visual, and somatosensory systems. The brain’s cortical centers control voluntary motor function.
Spinal Level[edit | edit source]
The muscle spindle is the main mechanoreceptor at the spinal level. Afferent fibers from the muscle spindles synapse with spinal interneurons, eliciting an efferent response which causes either facilitation or inhibition of the motor neuron "stretch reflex". If an external force, such as an increase in load, lengthens the muscle, the rate of the spindle afferents firing increases. The stretch produced by the load is counteracted by a reflex contraction maintaining the muscle length close to a set value. The stretch reflex allows muscle tone to be regulated quickly and efficiently without direct interaction by higher centers.
Motor Cortex Level[edit | edit source]
The highest level of the CNS involved in motor control is the primary motor cortex. Coordinating and planning of complex sequences of movement relies on mechanoreceptor feedback to provide conscious awareness of the joint position and speed of the intended movement. The appreciation of joint position sense at the highest or cognitive level needs to be included in the RNT program. Both active and passive joint repositioning can be utilized to enhance cognitive appreciation of joint position. The repetition of these movements will maximally stimulate the conversion of conscious programming to unconscious programming. To take this one step further, primary motor cortex involvement occurs in activities that last 300 msec or longer.
Pathophysiology[edit | edit source]
Following an injury to a joint, disruption to the articular mechanoreceptors inhibits normal neuromuscular reflex joint stabilization which may lead to proprioceptive deficits. This partial deafferentation results in a proprioceptive deficit, which contributes to repetitive injuries and the progressive decline of the joint. Injuries to the muscles may also lead to a compromise of the afferent feedback from the muscle spindles. Motor programs are adapted to receive specific sensory feedback for the accurate execution of various motor tasks. Injury causes sensory feedback which does not match the existing motor program, causing changes in the normal and coordinated patterns of the muscles and functional joint stability.
Rehabilitation[edit | edit source]
The RNT program as part of the functional exercise progression initially focuses on dynamic stabilization at the spinal level. Rhythmic stabilization exercises in the open chain position encourage co-contraction of the musculature about the shoulder, providing a foundation for dynamic neuromuscular stabilization. Taking advantage of the stretch reflex, rhythmic stabilization activities create a change in the desired length of the muscle, resulting in reflex muscular splinting. Efficient co-activation restores the force couples necessary to balance joint forces and increase joint congruency, thereby reducing the loads imparted onto the static structures.
The Shoulder[edit | edit source]
These exercises should initially focus on static stabilization of the shoulder joint and progression would then focus on stimulating multiple systems, including vision. Exercises designed to develop dynamic stabilization should progress from bilateral to unilateral, supported to unsupported, and minimal capsular stress to maximal capsular stress. Through therapeutic exercise, the clinician challenges the patient with activities that progress from slow speed to fast speed, from stable surfaces to unstable surfaces, from gradual challenges to sudden challenges, and from simple coordination to complex coordination.
The Knee[edit | edit source]
After injury to the anterior cruciate ligament, proprioceptive defects have been reported. Reconstructing the anterior cruciate ligament seems to improve afferent input needed for functional joint stability, and histologic studies have shown a repopulation of mechanoreceptors in anterior cruciate ligament graft tissue. Exercises to enhance motor control therefore are essential after an anterior cruciate ligament reconstruction. Several anterior cruciate ligament prevention programs also are being developed. Most aim at increasing injury awareness and enhancing neuromuscular control through agility and proprioceptive drills. More data are needed to ascertain the essential elements necessary for a reliable, easy to implement, and effective anterior cruciate ligament prevention program.
The Ankle[edit | edit source]
If exercises to enhance proprioception can improve functional stability after an injury, it seems logical that such programs enhancing detection of foot motion and making postural adjustments, also should be appropriate in initial conditioning programs to prevent ankle injuries. Balance training begun on a flat board, advancing to a wobble board, and then to an unstable surface such as a foam pad, now is advocated by several authors as an essential component of conditioning. Exercises can be done initially with two legs and then with one leg, and with the eyes open followed by the eyes closed. The athlete also should be encouraged to practice balancing after single hop drills and progress to various patterns of hopping on stable and unstable surfaces, first with both legs, then with one leg, and with the eyes open followed by the eyes closed.
REFERNCES[edit | edit source]
- John A. Guido J, Stemm J. Reactive Neuromuscular Training: A Multi-level Approach to Rehabilitation of the Unstable Shoulder [Internet]. PubMed Central (PMC). 2022 [cited 30 May 2022]. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2953291/
- Cook G, Burton L, Fields K. Reactive neuromuscular training for the anterior cruciate ligament-deficient knee: a case report. J Athl Train. 1999;34(2):194–201.
- Etty Griffin LY. Neuromuscular training and injury prevention in sports. Clin Orthop Relat Res [Internet]. 2003 [cited 2022 May 30];409:53–60. Available from: https://journals.lww.com/clinorthop/fulltext/2003/04000/neuromuscular_training_and_injury_prevention_in.8.aspx
- Using Reactive Neuromuscular Training To Improve Shoulder Stability - last accessed 23/6/2022
- Reactive Neuromuscular Training For Knee Valgus - last accessed 23/6/2022
- The Ankle Series: Reactive Neuromuscular Training - Ankle & Glutes - last accessed 23/6/2022