Muscles, motor control and spinal stability Gail Nankivell Physiotherapist The Children’s Hospital at Westmead

Overview Stability Model of Function Motor Control Muscle Systems

What is Stability? Ability of the neuromuscular system to control and protect the spine (joint) from injury or reinjury Hodges 2003

Spinal stability 1.Control of spinal orientation - maintenance of overall spinal posture 2.Control of inter segmental relationship of each lumbar segment and the pelvis

Strategies for stability Muscle capacity  Strength  Endurance  Bracing and co contraction

Strategies for stability Muscle Control  Coordination & sequencing of activation  Control  Timing → Right muscle at right time with the right amount of force

Integrated Model of Function

Physical Examination Posture and movement analysis - static - functional Specific examination (active & manual) Examination of nervous system

Physical Examination Local muscle system - tests of muscle control - task-specific tests - strength & endurance Sensorimotor control - joint position sense - balance Work/functional tasks

Motor control Patterning or timing of muscle action & inaction Coordinated muscle action for stability & motion control Restoration of motor control → exercises that sequence muscle activation Imagery to restore neural patterning & increase strength (Comerford & Mottram 2001;Daneels et al 2001; Hodges et al 1996,2000) (Lee 2001;Richardson et al 1999) (Gandevia 1999; Yule & Cole 1992)

Muscle Systems Global: regional stabilisation Local: segmental and intrapelvic stabilisation Some muscles belong to both systems depending on the task. (Bergmark 1989)

Muscle systems

Muscle systems - Global

Action is direction specific Generate torque and control motion  concentrically  isometrically  eccentrically

Muscle systems - Global Maintains postural orientation Maintains equilibrium Produces power Facilitate by using verbs or instructions.

Muscle systems - Global Integrated sling system Muscles may overlap and interconnect, depending on the task Slings may all be part of one interconnected system (Vleeming et al 1995; Snijders et al 1995)

Global System - Dysfunction Weakness Non recruitment or delay Tightness / change in muscle length Imbalance in muscle activity Muscles may be over active

Muscle System - Local

Maintain a continuous low activity Increase in action prior to increase load or motion Is not direction specific Fine tunes interspinal segments Anticipatory Facilitate with use of imagery Muscles recruit best in neutral spine

Muscle System When the local system works correctly Applies compression to pelvis (form closure) Pelvis then ready to accept load from global system

Transverse abdominis

Transversus Abdominus Anticipatory for stabilisation of low back and pelvis prior to UL/LL movement Increases SIJ stiffness via thoracodorsal fascia (with multifidus) Helps stabilise pubic symphysis with pubococcygeus Contracts in response to PF contraction (Hodges & Richardson 1996,1997) (Richardson et al 2002; Barker & Briggs 1999) (Sapsford et al 2001)

Dysfunction of TrA Timing delay or absence in patients with LBP Loss of intrapelvic stability(SIJ & Pubic Symphysis) (Hodges & Richardson 1997,1999,Hodges 2001)

Multifidus

Deep & superficial fibres Anticipatory for stabilisation of lumbar spine prior to UL initiation Deep fibres bulge to tighten TDF Superficial fibres – direction dependent Co-contraction with TrA (& fascia) -`circle of integrity’ Control of sacral position (with PF) (Moseley et al 2002) (Gracovetsky 1990, Vleeming et al 1995) (Richardson et al 2002)

Multifidus - dysfunction Atrophies & delayed or absent in patients with low back pain & pelvic pain Retrain & hypertrophy to rehabilitate (Hides et al ;Daneels et al 2000, 2001;O’Sullivan 1997,2000; Hungerford 2002;Moseley et al 2002)

Pelvic floor

Pelvic Floor Stabilisation of pelvic girdle - pubic symphysis - sacral position( with multifidus) Maintenance of urinary & faecal continence Supports internal pelvic organs (Ashton & Miler et al 2001; Bo & Stein 1994; Contantinou & Govan 1982; Diez et al 2003; Peschers et al 2001; Sapsford et al 2001)

Pelvic Floor Contracts in response to hollowing & bracing command Can facilitate PF by co activating abdominals & vice versa Reflex connection between PF & urethra (Sapsford et al 2001;Constantinou & Govan 1982)

Pelvic Floor - Dysfunction Incontinence - urinary & faecal Loss of intrapelvic stability

Diaphragm

Stabilizer of the trunk for postural support Anticipatory with TrA prior to shoulder flexion (Hodges 1997;2000)

Diaphragm Diaphragm EMG : - increased tonic activity - phasic modulation with respiration - phasic modulation with movement

Diaphragm

Loss or reduction of tonic function (& phasic modulation associated with arm movement) of diaphragm & TrA after 60 seconds of hypercapnoea (Hodges 2001)

Local System Dysfunction Timing Atrophy Loss of Tonic function Loss of coordination with other local muscles Asymmetry

Thorax Integrated model of function Stability & motor control Role in UL function, neck, lumbopelvic & LL function Global & local muscle systems Control of scapula & glenohumeral joint

Thorax Longissimus & multifidus activity during seated rotation Longissimus direction specific Multifidus- No difference between directions at T5 (Lee,Coppieters & Hodges Spine 2005)

Cervical Spine Deep neck flexors vs. SCM & scalene Loss of recruitment of DNF in patients with neck pain Greater co activation of superficial neck flexors & extensors in neck pain Inability to relax muscles after completion of task (Jull et al 2007) (Johnston et al 2007)

Retraining the Core Neutral Spine is best position to learn recruitment of core muscles (Sapsford 2001) Post pelvic tilt position will recruit external obliques TA best recruited in neutral or slightly excessive lordosis (ant pelvic tilt)

Postural Re-education In crook lying Sitting- reset the pyramid base Side lying Prone Standing One leg stance (load transference)

Retrain the Core Downtrain/relax the global system Isolate the muscle Train for endurance & co-contraction with other muscles of the core Maintain neutral position and add load (trunk-leg;trunk-arm dissociation;ball)

Retrain the Core Co-contact the entire core then integrate into functional positions Once local system working well integrate/retrain breathing patterns Coordinate with global system (ie move in & out of neutral spine: flex, extend, rotate.. without segmental or regional collapse)

TA & PF–imagery cues Draw the ASIS together (string, wire) Vaginal lift, testicular lift Tension (or string) from inner thigh up into the pelvic floor String betw PS & coccyx PF squeezes & lifts

Multifidus –imagery cues (Lee) Draw the PSIS s together (a force,line) Pelvic floor Barbie doll leg pulled off- use a force coming from inside groin to connect it back into the socket. Wire/strings Groin-MF;PS-MF;Leg- MF;ASIS-MF;PF-MF

Patterning of mm recruitment in OLS (controls) Prior:Transverse fibres OI & multif ; then feedforward activation of TrA;trans fibres OI & multif to stabilise interseg lumbar motion and TrA + OI facilitate post rotation of inominate,multif activation for sacral nutation = SIJ close pack position

Mm recruitment in OLS Glut max, glut med, add long & TFL activate after initiation of motion- they maintain hip –pelvic alignment during single leg support Biceps fem activity decreased during single leg support

Assessment of Load Transfer thru pelvis Forward flexion test-Standing Stork Test (Gillet or one leg standing test)