Sensorimotor System – What does it mean & What’s the implication for rehab? Bec van De Scheur

IMG_2527After hitting heavy traffic, turning what should have been a swift two hour car trip into an eventful six hour journey to Birmingham, we finally reached the Therapy Expo 2017!

 

Fuelled with coffee, we sat in on a number of interesting presentations. Although there was diversity amongst the guest speakers a common theme seemed to present itself, the role of the sensorimotor system in injury rehabilitation.

 

Steven Hawking said it perfectly when he stated:

 

“Intelligence is the ability to adapt to change”

 

The human body is of no exception. Our desire to move after injury sees that we will go to great lengths to keep our bodies mobile. Often completely subconscious, we find ways to move around pain, stiffness, or imbalances. Thus, compensatory movement patterns or “muscle patterns” are born.

 

Jo Gibson [Twitter: @shouldergeek1], well renowned shoulder rehabilitation specialist, whose lecture we were lucky enough to attend at the Expo, has been quoted to explain it like this in relation to the shoulder:Jo Gibson januar 2016 (2)_edited1

 

“Muscle Patterning refers to inappropriate recruitment, commonly of the torque producing muscles of the glenohumeral joint e.g. Latissimus Dorsi, Pectoralis Major, Anterior /Posterior Deltoid. This unbalanced muscle action is involuntary and ingrained. Patients with muscle patterning essentially have a muscle recruitment sequencing problem that results in abnormal force couples, destabilising the joint.”

It is an important topic, as failure to correctly diagnose a structural instability versus a functional instability is a common factor in patients failing conventional rehabilitation or surgery.

‘Rehabilitation in this situation should be aimed at ‘normalising’ muscle recruitment patterns around the shoulder girdle and this involves appropriate facilitation throughout the kinetic chain. Balance, coordination and core control are all factors that must be addressed to optimise neuromuscular control mechanisms.’(1)

 

Our ability to adapt to change is both the human body’s greatest strength and its biggest weakness.

As a short term strategy compensation is a great tool. It is protective against further injury and it enables us to get on with our daily function. However, when these newfound motor patterns become long term and supersede our normal programming we will at some stage hit a point of failure, which usually manifests as injury or failed rehab.

 

It can be explained like this…..

 

Your weekend football team is down a player and you have no choice but to replace your star striker with the goalkeeper. Chances are he will manage to get the job done for a period of time, but because his training has not been specific to the role of striker and he is not conditioned or well rehearsed to the demands of this position, at some point in the game he will fatigue, his reaction time will diminish and his ability to generate power and keep up with the pace of the game will become apparent, leaving him vulnerable to injury.

 

Similarly, if you delegate a task to a muscle that it is not designed for, it can deal for a time, but ultimately it will not be able to withstand the extra demands that have been placed upon it.

 

For therapists this is very important to recognise as it will guide how we structure our rehabilitation. When patterns become maladaptive and cemented centrally, rehabilitation takes on a different level of complexity. We are no longer treating an isolated system.

 

It is easier to learn than to unlearn a skill. My father always says, “Practice does not make perfect, perfect practice makes perfect”. As performing something in a sub optimal way over and over again only leads you further away from skill mastery.

 

So lets break it down….

 

What does sensorimotor mean?

 

The term sensorimotor system describes, ‘the sensory, motor, and central integration and processing components involved in maintaining functional joint stability’. This encompasses neuromuscular control and proprioception. (2)

 

Sensorimotor Diagram
Neural Basis of sensorimotor learning: modifying internal [Lalazar & Vaadia, 2008] https://www.sciencedirect.com/science/article/pii/S0959438808001578

Lets look at this in relation to a common injury such as an inversion injury of the ankle….

 

It is generally known that the primary risk factor for an ankle sprain remains a history of a previous sprain (5). It is thought that the initial damage to the lateral ankle ligaments alters the function of mechanoreceptors of these ligaments disrupting the ability to sense motion at the joint (4) and can lead to functional instability of the ankle. It is often described as frequent episodes of “giving way” or feelings of instability at the ankle joint.

 

A number of authors support the idea that some patients with functional ankle instability have deficits in neuromuscular preparatory or anticipatory control, which increases the risk of injury to the ankle, as it is less protected in an inadequate ankle joint position. Add to this a sub optimal rehabilitation program and paving the way towards a chronic ankle issue.

 

So what does this mean in terms of exercise prescription?

 

Benoy Mathew [Twitter: @function2fitnes] from Harley Street Physiotherapy during his talk regarding “the problem ankle” discussed the benefits of dynamic exercises such as sport specific plyometrics, which utilises sensorimotor training to promote anticipatory postural adjustments as well as optimise agility, landing technique and reaction time.

 

When it comes to overall running efficiency Mike Antoniades [Twitter: @runningschool], Performance & Rehabilitation Director of The Running School agrees:

 

“To change running technique, theoretical information and tips will not do the trick. The body needs to learn movement through movement – mostly while running but also through other re-patterning exercises”

(1)

 

During his workshop at the Therapy Expo, Mike gave us great examples during a live running assessment of particular movement dysfunctions that result from motor patterning, which often lead to muscle imbalances, poor technique and may be a factor in the recurrence of injury.

 

A common example is poor gluteal activation, which leads to compensatory hamstring dominance. Recognising this as the main offender of a patients running pain is a great start but strength training alone will only get you so far if it is a neuromuscular issue and ‘sensory motor amnesia’ is the primary reason why certain muscles fail to activate during movement.

 

There is a lot to think about during clinical diagnosis to ensure we are not ‘band-aiding’ a sensorimotor issue with strength exercises and manual therapy.

 

It is our responsibility as physiotherapists to ensure that we are continuously looking for opportunities to enhance our clinical skills. By optimising our assessments we are giving each person that seeks our advice the best opportunity to reach their full potential.

 

  1. Antoniades, M (2016), Mikes view on therapy expo 2016. Retrieved December 10, 2017, from http://runningschool.co.uk/blogs/mikes-view-on-therapy-expo-2016/
  2. Foundation of Sports Medicine Education and Research (1997). The role of proprioception and neuromuscular control in the management of knee and shoulder conditions.; August 22–24; Pittsburgh, PA.
  3. Gibson, J (n.d), Advances in rehabilitation of the shoulder. Retrieved December 10 2017, from http://www.physioroom.com/experts/expertupdate/interview_gibson_20041031_1.php
  4. Hertel J. (2002). Functional anatomy, pathomechanics, and pathophysiology of lateral ankle instability. Journal of Athletic Training. 37(4) 364–75.
  5. Milgrom C, et al. (1991). Risk factors for lateral ankle sprain: a pro- 
spective study among military recruits. Foot Ankle. 12(1), 
26–30.
  6. Lalazar & Vaadia, (2008). Neural Basis of sensorimotor learning: modifying internal models.  https://www.sciencedirect.com/science/article/pii/S0959438808001578

 

Bec van De Scheurcropped-logo-resize-21.png

Swimming related sports injuries

Swimming related sports injuries:

You may think that swimmers never get hurt. If so, read on Swimming is regarded as the ideal form of exercise because it is so injury-free. Physical problems only really emerge as a result of competitive training, combined with heavy land training. The result? Over-use or repetitive microtrauma injuries such as swimmer’s shoulder and breast-stroke knee . These two terms are just generalised names for a variety of injuries that can occur at the shoulder or knee joint because of the heavily repetitive nature of competitive swimming. This stress can be appreciated if you imagine a swimmer training 200-300 lengths per session, x 8+ sessions per week for eight months of the year – those arms certainly circle a lot of times! This is why efficient technique (with regular assessment) and even diet are vital to ensure a swimmer’s competitive career is as injury-free as possible.

Swimmer’s shoulder is more properly known as painful arc/ rotator cuff tendinitis, or shoulder impingement. In swimmers, painful arc/rotator cuff pain in the shoulder can occur in any of the following movements:

1 Adduction of the arm at the shoulder (when the extended arm is lifted sideways to vertical, away from the mid-line of the body)

2 When this movement is blocked

3 Flexion of the arm at the shoulder (when the extended arm is lifted out in front)

4 When this movement to left or right is blocked.

Pain occurs in the arc between 80-110 degrees. If little strength can be put against blocked movement, there could be a tear in the rotator cuff. Cause: over-use of any of the four shoulder muscles, poor blood supply or poor swimming efficiency and technique. This form of trauma often accompanies shoulder impingement (which Dr Kemp also described). Treatment involves rest and assessment of the swimmer’s bio-mechanics in order to identify any faults that may contribute to the injury. It is also important to look at the land conditioning or weight training the swimmer is undertaking, again to identify possible injury factors.

The acromioclavicular joint (where the clavicle and scapula meet) may develop degenerative arthritic changes, particularly from damage in resistance weight training. The repetitive motions of swimming may also stress this joint. The problem is usually treated conservatively with rest; however, if there is no satisfactory response, non-steroidal anti-inflammatory drugs, local heat and ice contrast and occasionally a cortisone injection may be needed.

Arthritis of the glenohumeral joint (where the head of the humerus meets the glenoid cavity) may be seen in the masters age group, though it is rare in the young. Inflammatory arthritis (rheumatoid) may, however, affect the young athlete; it destroys the surface of the joints. Massive arthritic destruction of the glenohumeral joint may require prosthetic joint replacement or joint fusion. Obviously neither would allow an athlete to effectively take part in competitive swimming.

 

Where the force comes from

The propulsive force of a swimmer comes from the upper body, with the legs acting as stabilisers and providing little propulsion. The shoulder joint must withstand repetitive microtrauma and is subject to overuse syndromes. However, not all swimmers who train under similar conditions develop significant interfering shoulder problems – most will escape any ill effects. The most powerful swimming muscles are the adductors and internal rotators (subscaplaris, supraspinatus and teres major). In an unstable shoulder, the external rotators will be required to do extra work to restrain the humeral head from anterior translation during the press and in-sweep phases of the freestyle stroke. This can lead to overload, fatigue and secondary inflammation, and may account for the common complaint of posterior pain in an individual with anterior shoulder subluxation or dislocation.

Strengthening of the rotator-cuff muscles provides the best stability to the joint and decreases the chance of hypermobility. Military press (shoulder press), side raise with dumbbells (with external rotation), medicine ball exercises, lateral pull-downs and seated rows are examples of a few. As a theapist, I have come across patients presenting with problems in the sternoclavicular joints (where the sternum and the clavicle meet). Often they preesnt with dull aches and pains felt while exercising, particularly when my shoulder girdle is retracted (shoulders pulled back) – press-ups, bench press, seat row, reverse flies, and through all of the swimming strokes. The ligaments there to support and strengthen the joint seem to have lost all form of rigidity and stability as the head of the clavicle actually slips out of its socket (and then back in on protraction, shoulders forward). The problem only becomes painful after 1-2 hours in the pool, after continuous repetitive movements. The pain is more of a dull ache, and all I feel comfortable doing is stretching because it seems to ease the pressure and discomfort around the sternoclavicular joint.

 

Dealing with breast-stroke knee

While looking at research for this article I came across an excellent piece on knee injuries in breast-stroke swimmers from McMaster (1996). He reported that the alignment of the knee centre relative to the hip centre during the start of the breast-stroke kick affects the development in the medial collateral ligament (which stabilises the knee on the inside of the leg) and capsule. The optimum initiating position from the breast-stroke kick is with the hip and knee centres aligned. When the knee centre is narrow or wide of the hip centre, it causes increased stress on the medial collateral joint structures. Exceeding the elastic limits of the ligament will cause damage and injury. In young swimmers, this form of stress could open growth plates of the femur and tibia and cause micro-injury which will result in inflammation and thus seriously impair training. If you’re a coach, what’s the breast-stroke kick like in your younger swimmers?

Finally, McMaster noted that there is a high risk of the patella (knee-cap) riding laterally during the breast-stroke kick. This is magnified when the patella tendon attachment site at the tibial tubercle is placed in an extremely rotated position. This is measured clinically as the Q angle. Weakness of the vastus medialis (the inner thigh muscle which is part of the quadriceps) can decrease effectiveness in ensuring central tracking of the patella. If dislocation occurs, surgery is almost certain. Other minor causes include weak abductors and decreased flexibility of the hamstrings, adductor muscles and the iliotibial band. The patella in particular will be tender if palpated. Treatment can be confirmed by x-rays (to determine the lining of the patella and tendons) and focus on reducing the inflammation. When planning land conditioning for swimmers, I strongly recommend, especially for breast-stroke swimmers, including a range of quadriceps exercises such as squats, leg press, cycling, lunges and leg extensions, and also leg raises for the abductor and adductor muscles, followed by quality stretches.

The fibrocartilagenous meniscus (pad-like structures protecting bone ends) of the knee may be injured during combined bending and twisting movements. As the knee flexes under a load, the meniscus can become trapped between the joint surfaces, causing a shearing force that produces a tear. The signs of such an injury include a popping and sapping noise, and buckling and possible locking of the knee. Unfortunately, meniscus tears do not heal at all well and may need therapy. In masters swimmers, generative arthritis or wearing of the knee surface may also result in tearing of the meniscus and is not uncommon.

 

How to Prevent Swimmer’s Shoulder?

There are several ways to reduce your chance of experiencing this injury:

1)      Taking time to warm up, warm down and properly stretch after your swim session.

2)      Strengthening the muscles around your shoulders is another good preventative measure. Try to incorporate shoulder exercises at least 3 times a week does reduce your chances of injury.

3)      Learn proper stroke technique by getting help from a coach at a local swim club, or there are many videos on the web that serve as great technique resources. Even better, get some lessons from a coach.

4)      If your shoulder starts to feel pain, STOP.  If you continue swimming through the pain, at least put on a pair of fins to reduce the pressure placed on your shoulders.

5)      Icing your shoulder is also a good preventive measure. When you are finished working out and you recognise some discomfort, take an ice pack or bag of ice and hold on the area for about 10 minutes. This can be repeated every 2 hours. Please always make sure ice packs are not put directly on to skin, wrap them in a damp towel or cloth.

Courtesy of peak performance